Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 11 Aug 2016 15:04:00 +0200 Arnd Bergmannwrote: > On Thursday, August 11, 2016 10:43:20 PM CEST Nicholas Piggin wrote: > > On Wed, 03 Aug 2016 22:13:28 +0200 > > Final ld time > > inclink > > real0m0.378s > > user0m0.304s > > sys 0m0.076s > > > > thinarc > > real0m0.894s > > user0m0.684s > > sys 0m0.200s > > This also still seems fine. > > > For both cases final link gets slower with thin archives. I guess there is > > some > > per-file overhead but I thought with --whole-archive it should not be that > > much > > slower. Still, overall time for main ar/ld phases comes out about the same > > in > > the end so I don't think it's too much problem. Unless ARM blows up > > significantly > > worse with a bigger config. > > Unfortunately I think it does. I haven't tried your latest series yet, > but I think the total time for removing built-in.o and relinking went > up from around 4 minutes (already way too much) to 18 minutes for me. > > > Linking with thin archives takes significantly more time in bfd hash lookup > > code. > > I haven't dug much further yet. > > Can you try the ARM allyesconfig with thin archives? I'll follow up with two > patches: one to get ARM to link without thin archives, and one that I used > to get --gc-sections to work. Okay send them over, I'll try digging into it. There is not much kbuild code to maintain so we don't have to switch every arch. It would be nice to though. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 11 Aug 2016 15:04:00 +0200 Arnd Bergmann wrote: > On Thursday, August 11, 2016 10:43:20 PM CEST Nicholas Piggin wrote: > > On Wed, 03 Aug 2016 22:13:28 +0200 > > Final ld time > > inclink > > real0m0.378s > > user0m0.304s > > sys 0m0.076s > > > > thinarc > > real0m0.894s > > user0m0.684s > > sys 0m0.200s > > This also still seems fine. > > > For both cases final link gets slower with thin archives. I guess there is > > some > > per-file overhead but I thought with --whole-archive it should not be that > > much > > slower. Still, overall time for main ar/ld phases comes out about the same > > in > > the end so I don't think it's too much problem. Unless ARM blows up > > significantly > > worse with a bigger config. > > Unfortunately I think it does. I haven't tried your latest series yet, > but I think the total time for removing built-in.o and relinking went > up from around 4 minutes (already way too much) to 18 minutes for me. > > > Linking with thin archives takes significantly more time in bfd hash lookup > > code. > > I haven't dug much further yet. > > Can you try the ARM allyesconfig with thin archives? I'll follow up with two > patches: one to get ARM to link without thin archives, and one that I used > to get --gc-sections to work. Okay send them over, I'll try digging into it. There is not much kbuild code to maintain so we don't have to switch every arch. It would be nice to though. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 11, 2016 10:43:20 PM CEST Nicholas Piggin wrote: > On Wed, 03 Aug 2016 22:13:28 +0200 > Arnd Bergmannwrote: > > > On Wednesday, August 3, 2016 2:44:29 PM CEST Segher Boessenkool wrote: > > > Hi Arnd, > > > > > > On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > > > > From my first look, it seems that all of lib/*.o is now getting linked > > > > into vmlinux, while we traditionally leave out everything from lib/ > > > > that is not referenced. > > > > > > > > I also see a noticeable overhead in link time, the numbers are for > > > > a cache-hot rebuild after a successful allyesconfig build, using a > > > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > > > > > > > $ time make skj30 vmlinux # before > > > > real2m8.092s > > > > user3m41.008s > > > > sys 0m48.172s > > > > > > > > $ time make skj30 vmlinux # after > > > > real4m10.189s > > > > user5m43.804s > > > > sys 0m52.988s > > > > > > Is it better when using rcT instead of rcsT? > > > > It seems to be noticeably better for the clean rebuild case, though > > not as good as the original: > > > > real3m34.015s > > user5m7.104s > > sys 0m49.172s > > > > I've also tried now with my own patch applied as well (linking > > each drivers/*/built-in.o into vmlinux rather than having them > > linked into drivers/built-in.o first), but that makes no > > difference. > > I just want to come back to this, because I've subbmitted the thin > archives kbuild patch, I wanted to make sure we're doing okay on > ARM/ARM64. I cross compiled with my laptop. > > For ARM64 allyesconfig: > > After building then removing all built-in.o then rebuilding vmlinux: > inclink > time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux > real1m18.977s > user2m14.512s > sys 0m29.704s > > thinarc > time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux > real1m18.433s > user2m6.128s > sys 0m28.372s > > > Final ld time > inclink > real0m4.005s > user0m3.464s > sys 0m0.536s > > thinarc > real0m5.841s > user0m4.916s > sys 0m0.916s > > > Build directory size is of course much better (3953MB vs 5519MB). Ok, looks great. Some downsides and some upsides here, but overall I think this is a win. > > For ARM, defconfig > > After building then removing all built-in.o then rebuilding vmlinux: > inclink > real 0m19.593s > user 0m22.372s > sys 0m6.428s > > thinarc > real 0m18.919s > user 0m21.924s > sys 0m6.400s > > > Final ld time > inclink > real 0m0.378s > user 0m0.304s > sys 0m0.076s > > thinarc > real0m0.894s > user0m0.684s > sys 0m0.200s This also still seems fine. > For both cases final link gets slower with thin archives. I guess there is > some > per-file overhead but I thought with --whole-archive it should not be that > much > slower. Still, overall time for main ar/ld phases comes out about the same in > the end so I don't think it's too much problem. Unless ARM blows up > significantly > worse with a bigger config. Unfortunately I think it does. I haven't tried your latest series yet, but I think the total time for removing built-in.o and relinking went up from around 4 minutes (already way too much) to 18 minutes for me. > Linking with thin archives takes significantly more time in bfd hash lookup > code. > I haven't dug much further yet. Can you try the ARM allyesconfig with thin archives? I'll follow up with two patches: one to get ARM to link without thin archives, and one that I used to get --gc-sections to work. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 11, 2016 10:43:20 PM CEST Nicholas Piggin wrote: > On Wed, 03 Aug 2016 22:13:28 +0200 > Arnd Bergmann wrote: > > > On Wednesday, August 3, 2016 2:44:29 PM CEST Segher Boessenkool wrote: > > > Hi Arnd, > > > > > > On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > > > > From my first look, it seems that all of lib/*.o is now getting linked > > > > into vmlinux, while we traditionally leave out everything from lib/ > > > > that is not referenced. > > > > > > > > I also see a noticeable overhead in link time, the numbers are for > > > > a cache-hot rebuild after a successful allyesconfig build, using a > > > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > > > > > > > $ time make skj30 vmlinux # before > > > > real2m8.092s > > > > user3m41.008s > > > > sys 0m48.172s > > > > > > > > $ time make skj30 vmlinux # after > > > > real4m10.189s > > > > user5m43.804s > > > > sys 0m52.988s > > > > > > Is it better when using rcT instead of rcsT? > > > > It seems to be noticeably better for the clean rebuild case, though > > not as good as the original: > > > > real3m34.015s > > user5m7.104s > > sys 0m49.172s > > > > I've also tried now with my own patch applied as well (linking > > each drivers/*/built-in.o into vmlinux rather than having them > > linked into drivers/built-in.o first), but that makes no > > difference. > > I just want to come back to this, because I've subbmitted the thin > archives kbuild patch, I wanted to make sure we're doing okay on > ARM/ARM64. I cross compiled with my laptop. > > For ARM64 allyesconfig: > > After building then removing all built-in.o then rebuilding vmlinux: > inclink > time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux > real1m18.977s > user2m14.512s > sys 0m29.704s > > thinarc > time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux > real1m18.433s > user2m6.128s > sys 0m28.372s > > > Final ld time > inclink > real0m4.005s > user0m3.464s > sys 0m0.536s > > thinarc > real0m5.841s > user0m4.916s > sys 0m0.916s > > > Build directory size is of course much better (3953MB vs 5519MB). Ok, looks great. Some downsides and some upsides here, but overall I think this is a win. > > For ARM, defconfig > > After building then removing all built-in.o then rebuilding vmlinux: > inclink > real 0m19.593s > user 0m22.372s > sys 0m6.428s > > thinarc > real 0m18.919s > user 0m21.924s > sys 0m6.400s > > > Final ld time > inclink > real 0m0.378s > user 0m0.304s > sys 0m0.076s > > thinarc > real0m0.894s > user0m0.684s > sys 0m0.200s This also still seems fine. > For both cases final link gets slower with thin archives. I guess there is > some > per-file overhead but I thought with --whole-archive it should not be that > much > slower. Still, overall time for main ar/ld phases comes out about the same in > the end so I don't think it's too much problem. Unless ARM blows up > significantly > worse with a bigger config. Unfortunately I think it does. I haven't tried your latest series yet, but I think the total time for removing built-in.o and relinking went up from around 4 minutes (already way too much) to 18 minutes for me. > Linking with thin archives takes significantly more time in bfd hash lookup > code. > I haven't dug much further yet. Can you try the ARM allyesconfig with thin archives? I'll follow up with two patches: one to get ARM to link without thin archives, and one that I used to get --gc-sections to work. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wed, 03 Aug 2016 22:13:28 +0200 Arnd Bergmannwrote: > On Wednesday, August 3, 2016 2:44:29 PM CEST Segher Boessenkool wrote: > > Hi Arnd, > > > > On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > > > From my first look, it seems that all of lib/*.o is now getting linked > > > into vmlinux, while we traditionally leave out everything from lib/ > > > that is not referenced. > > > > > > I also see a noticeable overhead in link time, the numbers are for > > > a cache-hot rebuild after a successful allyesconfig build, using a > > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > > > > > $ time make skj30 vmlinux # before > > > real 2m8.092s > > > user 3m41.008s > > > sys 0m48.172s > > > > > > $ time make skj30 vmlinux # after > > > real 4m10.189s > > > user 5m43.804s > > > sys 0m52.988s > > > > Is it better when using rcT instead of rcsT? > > It seems to be noticeably better for the clean rebuild case, though > not as good as the original: > > real 3m34.015s > user 5m7.104s > sys 0m49.172s > > I've also tried now with my own patch applied as well (linking > each drivers/*/built-in.o into vmlinux rather than having them > linked into drivers/built-in.o first), but that makes no > difference. I just want to come back to this, because I've subbmitted the thin archives kbuild patch, I wanted to make sure we're doing okay on ARM/ARM64. I cross compiled with my laptop. For ARM64 allyesconfig: After building then removing all built-in.o then rebuilding vmlinux: inclink time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux real1m18.977s user2m14.512s sys 0m29.704s thinarc time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux real1m18.433s user2m6.128s sys 0m28.372s Final ld time inclink real0m4.005s user0m3.464s sys 0m0.536s thinarc real0m5.841s user0m4.916s sys 0m0.916s Build directory size is of course much better (3953MB vs 5519MB). For ARM, defconfig After building then removing all built-in.o then rebuilding vmlinux: inclink real0m19.593s user0m22.372s sys 0m6.428s thinarc real0m18.919s user0m21.924s sys 0m6.400s Final ld time inclink real0m0.378s user0m0.304s sys 0m0.076s thinarc real0m0.894s user0m0.684s sys 0m0.200s For both cases final link gets slower with thin archives. I guess there is some per-file overhead but I thought with --whole-archive it should not be that much slower. Still, overall time for main ar/ld phases comes out about the same in the end so I don't think it's too much problem. Unless ARM blows up significantly worse with a bigger config. Linking with thin archives takes significantly more time in bfd hash lookup code. I haven't dug much further yet. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wed, 03 Aug 2016 22:13:28 +0200 Arnd Bergmann wrote: > On Wednesday, August 3, 2016 2:44:29 PM CEST Segher Boessenkool wrote: > > Hi Arnd, > > > > On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > > > From my first look, it seems that all of lib/*.o is now getting linked > > > into vmlinux, while we traditionally leave out everything from lib/ > > > that is not referenced. > > > > > > I also see a noticeable overhead in link time, the numbers are for > > > a cache-hot rebuild after a successful allyesconfig build, using a > > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > > > > > $ time make skj30 vmlinux # before > > > real 2m8.092s > > > user 3m41.008s > > > sys 0m48.172s > > > > > > $ time make skj30 vmlinux # after > > > real 4m10.189s > > > user 5m43.804s > > > sys 0m52.988s > > > > Is it better when using rcT instead of rcsT? > > It seems to be noticeably better for the clean rebuild case, though > not as good as the original: > > real 3m34.015s > user 5m7.104s > sys 0m49.172s > > I've also tried now with my own patch applied as well (linking > each drivers/*/built-in.o into vmlinux rather than having them > linked into drivers/built-in.o first), but that makes no > difference. I just want to come back to this, because I've subbmitted the thin archives kbuild patch, I wanted to make sure we're doing okay on ARM/ARM64. I cross compiled with my laptop. For ARM64 allyesconfig: After building then removing all built-in.o then rebuilding vmlinux: inclink time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux real1m18.977s user2m14.512s sys 0m29.704s thinarc time make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8 vmlinux real1m18.433s user2m6.128s sys 0m28.372s Final ld time inclink real0m4.005s user0m3.464s sys 0m0.536s thinarc real0m5.841s user0m4.916s sys 0m0.916s Build directory size is of course much better (3953MB vs 5519MB). For ARM, defconfig After building then removing all built-in.o then rebuilding vmlinux: inclink real0m19.593s user0m22.372s sys 0m6.428s thinarc real0m18.919s user0m21.924s sys 0m6.400s Final ld time inclink real0m0.378s user0m0.304s sys 0m0.076s thinarc real0m0.894s user0m0.684s sys 0m0.200s For both cases final link gets slower with thin archives. I guess there is some per-file overhead but I thought with --whole-archive it should not be that much slower. Still, overall time for main ar/ld phases comes out about the same in the end so I don't think it's too much problem. Unless ARM blows up significantly worse with a bigger config. Linking with thin archives takes significantly more time in bfd hash lookup code. I haven't dug much further yet. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Saturday, August 6, 2016 2:17:16 PM CEST Nicholas Piggin wrote: > On Fri, 05 Aug 2016 21:16:00 +0200 > Arnd Bergmannwrote: > > > On Saturday, August 6, 2016 2:16:42 AM CEST Nicholas Piggin wrote: > > > > > > > > diff --git a/include/asm-generic/vmlinux.lds.h > > > > b/include/asm-generic/vmlinux.lds.h > > > > index 0ec807d69f18..7a3ad269fa23 100644 > > > > --- a/include/asm-generic/vmlinux.lds.h > > > > +++ b/include/asm-generic/vmlinux.lds.h > > > > @@ -433,7 +433,7 @@ > > > > * during second ld run in second ld pass when generating System.map */ > > > > #define TEXT_TEXT\ > > > > ALIGN_FUNCTION(); \ > > > > - *(.text.hot .text .text.fixup .text.unlikely) \ > > > > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > > > > *(.ref.text)\ > > > > MEM_KEEP(init.text) \ > > > > MEM_KEEP(exit.text) \ > > > > > > > > > > > > It also got much faster again, the link time for an allyesconfig > > > > kernel is now 18 minutes instead of 10 hours, but it's still > > > > much worse than the 2 minutes I had earlier or the four minutes > > > > with the previous patch. > > > > > > Are you using the patches I just sent? > > > > Not yet, I was still busy with the older version, and trying to > > figure out exactly what went wrong in ld.bfd. FWIW, I first tried > > to see if the hash tables were just too small, but as it turned > > out that was not the problem. When I tried to change the default > > hash table sizes, making them bigger only made things slower. > > > > I also found the --hash-size=xxx option, which has a significant > > impact on runtime speed. Interestingly again, using sizes less > > than the default made things faster in practice. If we can > > work out the optimum size for the kernel build, that might > > shave a few minutes off the total build time. > > > > > Either way, you also need > > > to do the same for data and bss sections as you are using > > > -fdata-sections too. > > > > Right. > > > > > I've found virtually no build time regression on powerpc or x86 > > > when those are taken care of properly (x86 numbers I sent are typo, > > > it's not 5m20, it's 5m02). > > > > Interesting. I wonder if it's got something to do with the > > generation of the branch trampolines on ARM, as we have a lot > > of them on an allyesconfig. > > Powerpc generates quite a few branch trampolines as well, so > I'm not sure if that would be the issue. Can you get a profile > of the link? CPU: AMD64 family15h, speed 2600 MHz (estimated) Counted CPU_CLK_UNHALTED events (CPU Clocks not Halted) with a unit mask of 0x00 (No unit mask) count 10 samples %image name symbol name 1212556 63.6990 ld-new bfd_hash_lookup 416050 21.8563 ld-new bfd_hash_hash 64861 3.4073 no-vmlinux /no-vmlinux 59038 3.1014 ld-new bfd_hash_traverse 13873 0.7288 ld-new bfd_get_next_section_by_name 9880 0.5190 ld-new strrevcmp I've manually marked bfd_hash_hash as __attribute__((noinline)) to see it separately from bfd_hash_lookup. The vast majority of these calls seem to come from _bfd_elf_strtab_add and from bfd_get_section_by_name/bfd_get_next_section_by_name. While I first thought the hash tables were too slow, investigating further showed that most of the hash tables are really small (and appropriately sized), we just do a lot of lookups on them. > Are you linking with archives? Do your input archives have a > symbol index built? yes, and don't know. I've moved on to your new patches now, will see how that goes. > > Is the 5m20 the total build time for the kernel, the time for > > rebuilding after a trivial change, or the time to call 'ld.bfd' > > once? > > 5m02 was the total time for x86 defconfig. With the powerpc > allyesconfig build, the final link: > > $ time ld -EL -m elf64lppc -pie --emit-relocs --build-id --gc-sections -X -o > vmlinux -T ./arch/powerpc/kernel/vmlinux.lds --whole-archive built-in.o > .tmp_kallsyms2.o > > real 0m15.556s > user 0m13.288s > sys 0m2.240s > > $ ls -lh vmlinux > -rwxrwxr-x 1 npiggin npiggin 279M Aug 6 14:02 vmlinux > > Without -pie --emit-relocs it's 11.8s and 150M but I'm using > emit-relocs for a post-link step. Interesting, that does sound more like an ARM specific bug in ld then. > > Are you using ld.bfd on x86 or ld.gold? For me ld.gold either > > works and is really fast, or it crashes, depending on the > > configuration. I also don't think it supports big-endian ARM > > (which is what allyesconfig ends up using). > > ld.bfd on both. Gold crashed on powerpc and I didn't try it on x86.
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Saturday, August 6, 2016 2:17:16 PM CEST Nicholas Piggin wrote: > On Fri, 05 Aug 2016 21:16:00 +0200 > Arnd Bergmann wrote: > > > On Saturday, August 6, 2016 2:16:42 AM CEST Nicholas Piggin wrote: > > > > > > > > diff --git a/include/asm-generic/vmlinux.lds.h > > > > b/include/asm-generic/vmlinux.lds.h > > > > index 0ec807d69f18..7a3ad269fa23 100644 > > > > --- a/include/asm-generic/vmlinux.lds.h > > > > +++ b/include/asm-generic/vmlinux.lds.h > > > > @@ -433,7 +433,7 @@ > > > > * during second ld run in second ld pass when generating System.map */ > > > > #define TEXT_TEXT\ > > > > ALIGN_FUNCTION(); \ > > > > - *(.text.hot .text .text.fixup .text.unlikely) \ > > > > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > > > > *(.ref.text)\ > > > > MEM_KEEP(init.text) \ > > > > MEM_KEEP(exit.text) \ > > > > > > > > > > > > It also got much faster again, the link time for an allyesconfig > > > > kernel is now 18 minutes instead of 10 hours, but it's still > > > > much worse than the 2 minutes I had earlier or the four minutes > > > > with the previous patch. > > > > > > Are you using the patches I just sent? > > > > Not yet, I was still busy with the older version, and trying to > > figure out exactly what went wrong in ld.bfd. FWIW, I first tried > > to see if the hash tables were just too small, but as it turned > > out that was not the problem. When I tried to change the default > > hash table sizes, making them bigger only made things slower. > > > > I also found the --hash-size=xxx option, which has a significant > > impact on runtime speed. Interestingly again, using sizes less > > than the default made things faster in practice. If we can > > work out the optimum size for the kernel build, that might > > shave a few minutes off the total build time. > > > > > Either way, you also need > > > to do the same for data and bss sections as you are using > > > -fdata-sections too. > > > > Right. > > > > > I've found virtually no build time regression on powerpc or x86 > > > when those are taken care of properly (x86 numbers I sent are typo, > > > it's not 5m20, it's 5m02). > > > > Interesting. I wonder if it's got something to do with the > > generation of the branch trampolines on ARM, as we have a lot > > of them on an allyesconfig. > > Powerpc generates quite a few branch trampolines as well, so > I'm not sure if that would be the issue. Can you get a profile > of the link? CPU: AMD64 family15h, speed 2600 MHz (estimated) Counted CPU_CLK_UNHALTED events (CPU Clocks not Halted) with a unit mask of 0x00 (No unit mask) count 10 samples %image name symbol name 1212556 63.6990 ld-new bfd_hash_lookup 416050 21.8563 ld-new bfd_hash_hash 64861 3.4073 no-vmlinux /no-vmlinux 59038 3.1014 ld-new bfd_hash_traverse 13873 0.7288 ld-new bfd_get_next_section_by_name 9880 0.5190 ld-new strrevcmp I've manually marked bfd_hash_hash as __attribute__((noinline)) to see it separately from bfd_hash_lookup. The vast majority of these calls seem to come from _bfd_elf_strtab_add and from bfd_get_section_by_name/bfd_get_next_section_by_name. While I first thought the hash tables were too slow, investigating further showed that most of the hash tables are really small (and appropriately sized), we just do a lot of lookups on them. > Are you linking with archives? Do your input archives have a > symbol index built? yes, and don't know. I've moved on to your new patches now, will see how that goes. > > Is the 5m20 the total build time for the kernel, the time for > > rebuilding after a trivial change, or the time to call 'ld.bfd' > > once? > > 5m02 was the total time for x86 defconfig. With the powerpc > allyesconfig build, the final link: > > $ time ld -EL -m elf64lppc -pie --emit-relocs --build-id --gc-sections -X -o > vmlinux -T ./arch/powerpc/kernel/vmlinux.lds --whole-archive built-in.o > .tmp_kallsyms2.o > > real 0m15.556s > user 0m13.288s > sys 0m2.240s > > $ ls -lh vmlinux > -rwxrwxr-x 1 npiggin npiggin 279M Aug 6 14:02 vmlinux > > Without -pie --emit-relocs it's 11.8s and 150M but I'm using > emit-relocs for a post-link step. Interesting, that does sound more like an ARM specific bug in ld then. > > Are you using ld.bfd on x86 or ld.gold? For me ld.gold either > > works and is really fast, or it crashes, depending on the > > configuration. I also don't think it supports big-endian ARM > > (which is what allyesconfig ends up using). > > ld.bfd on both. Gold crashed on powerpc and I didn't try it on x86. Ok. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Fri, 05 Aug 2016 21:16:00 +0200 Arnd Bergmannwrote: > On Saturday, August 6, 2016 2:16:42 AM CEST Nicholas Piggin wrote: > > > > > > diff --git a/include/asm-generic/vmlinux.lds.h > > > b/include/asm-generic/vmlinux.lds.h > > > index 0ec807d69f18..7a3ad269fa23 100644 > > > --- a/include/asm-generic/vmlinux.lds.h > > > +++ b/include/asm-generic/vmlinux.lds.h > > > @@ -433,7 +433,7 @@ > > > * during second ld run in second ld pass when generating System.map */ > > > #define TEXT_TEXT\ > > > ALIGN_FUNCTION(); \ > > > - *(.text.hot .text .text.fixup .text.unlikely) \ > > > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > > > *(.ref.text)\ > > > MEM_KEEP(init.text) \ > > > MEM_KEEP(exit.text) \ > > > > > > > > > It also got much faster again, the link time for an allyesconfig > > > kernel is now 18 minutes instead of 10 hours, but it's still > > > much worse than the 2 minutes I had earlier or the four minutes > > > with the previous patch. > > > > Are you using the patches I just sent? > > Not yet, I was still busy with the older version, and trying to > figure out exactly what went wrong in ld.bfd. FWIW, I first tried > to see if the hash tables were just too small, but as it turned > out that was not the problem. When I tried to change the default > hash table sizes, making them bigger only made things slower. > > I also found the --hash-size=xxx option, which has a significant > impact on runtime speed. Interestingly again, using sizes less > than the default made things faster in practice. If we can > work out the optimum size for the kernel build, that might > shave a few minutes off the total build time. > > > Either way, you also need > > to do the same for data and bss sections as you are using > > -fdata-sections too. > > Right. > > > I've found virtually no build time regression on powerpc or x86 > > when those are taken care of properly (x86 numbers I sent are typo, > > it's not 5m20, it's 5m02). > > Interesting. I wonder if it's got something to do with the > generation of the branch trampolines on ARM, as we have a lot > of them on an allyesconfig. Powerpc generates quite a few branch trampolines as well, so I'm not sure if that would be the issue. Can you get a profile of the link? Are you linking with archives? Do your input archives have a symbol index built? > Is the 5m20 the total build time for the kernel, the time for > rebuilding after a trivial change, or the time to call 'ld.bfd' > once? 5m02 was the total time for x86 defconfig. With the powerpc allyesconfig build, the final link: $ time ld -EL -m elf64lppc -pie --emit-relocs --build-id --gc-sections -X -o vmlinux -T ./arch/powerpc/kernel/vmlinux.lds --whole-archive built-in.o .tmp_kallsyms2.o real0m15.556s user0m13.288s sys 0m2.240s $ ls -lh vmlinux -rwxrwxr-x 1 npiggin npiggin 279M Aug 6 14:02 vmlinux Without -pie --emit-relocs it's 11.8s and 150M but I'm using emit-relocs for a post-link step. > Are you using ld.bfd on x86 or ld.gold? For me ld.gold either > works and is really fast, or it crashes, depending on the > configuration. I also don't think it supports big-endian ARM > (which is what allyesconfig ends up using). ld.bfd on both. Gold crashed on powerpc and I didn't try it on x86. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Fri, 05 Aug 2016 21:16:00 +0200 Arnd Bergmann wrote: > On Saturday, August 6, 2016 2:16:42 AM CEST Nicholas Piggin wrote: > > > > > > diff --git a/include/asm-generic/vmlinux.lds.h > > > b/include/asm-generic/vmlinux.lds.h > > > index 0ec807d69f18..7a3ad269fa23 100644 > > > --- a/include/asm-generic/vmlinux.lds.h > > > +++ b/include/asm-generic/vmlinux.lds.h > > > @@ -433,7 +433,7 @@ > > > * during second ld run in second ld pass when generating System.map */ > > > #define TEXT_TEXT\ > > > ALIGN_FUNCTION(); \ > > > - *(.text.hot .text .text.fixup .text.unlikely) \ > > > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > > > *(.ref.text)\ > > > MEM_KEEP(init.text) \ > > > MEM_KEEP(exit.text) \ > > > > > > > > > It also got much faster again, the link time for an allyesconfig > > > kernel is now 18 minutes instead of 10 hours, but it's still > > > much worse than the 2 minutes I had earlier or the four minutes > > > with the previous patch. > > > > Are you using the patches I just sent? > > Not yet, I was still busy with the older version, and trying to > figure out exactly what went wrong in ld.bfd. FWIW, I first tried > to see if the hash tables were just too small, but as it turned > out that was not the problem. When I tried to change the default > hash table sizes, making them bigger only made things slower. > > I also found the --hash-size=xxx option, which has a significant > impact on runtime speed. Interestingly again, using sizes less > than the default made things faster in practice. If we can > work out the optimum size for the kernel build, that might > shave a few minutes off the total build time. > > > Either way, you also need > > to do the same for data and bss sections as you are using > > -fdata-sections too. > > Right. > > > I've found virtually no build time regression on powerpc or x86 > > when those are taken care of properly (x86 numbers I sent are typo, > > it's not 5m20, it's 5m02). > > Interesting. I wonder if it's got something to do with the > generation of the branch trampolines on ARM, as we have a lot > of them on an allyesconfig. Powerpc generates quite a few branch trampolines as well, so I'm not sure if that would be the issue. Can you get a profile of the link? Are you linking with archives? Do your input archives have a symbol index built? > Is the 5m20 the total build time for the kernel, the time for > rebuilding after a trivial change, or the time to call 'ld.bfd' > once? 5m02 was the total time for x86 defconfig. With the powerpc allyesconfig build, the final link: $ time ld -EL -m elf64lppc -pie --emit-relocs --build-id --gc-sections -X -o vmlinux -T ./arch/powerpc/kernel/vmlinux.lds --whole-archive built-in.o .tmp_kallsyms2.o real0m15.556s user0m13.288s sys 0m2.240s $ ls -lh vmlinux -rwxrwxr-x 1 npiggin npiggin 279M Aug 6 14:02 vmlinux Without -pie --emit-relocs it's 11.8s and 150M but I'm using emit-relocs for a post-link step. > Are you using ld.bfd on x86 or ld.gold? For me ld.gold either > works and is really fast, or it crashes, depending on the > configuration. I also don't think it supports big-endian ARM > (which is what allyesconfig ends up using). ld.bfd on both. Gold crashed on powerpc and I didn't try it on x86. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Saturday, August 6, 2016 2:16:42 AM CEST Nicholas Piggin wrote: > > > > diff --git a/include/asm-generic/vmlinux.lds.h > > b/include/asm-generic/vmlinux.lds.h > > index 0ec807d69f18..7a3ad269fa23 100644 > > --- a/include/asm-generic/vmlinux.lds.h > > +++ b/include/asm-generic/vmlinux.lds.h > > @@ -433,7 +433,7 @@ > > * during second ld run in second ld pass when generating System.map */ > > #define TEXT_TEXT\ > > ALIGN_FUNCTION(); \ > > - *(.text.hot .text .text.fixup .text.unlikely) \ > > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > > *(.ref.text)\ > > MEM_KEEP(init.text) \ > > MEM_KEEP(exit.text) \ > > > > > > It also got much faster again, the link time for an allyesconfig > > kernel is now 18 minutes instead of 10 hours, but it's still > > much worse than the 2 minutes I had earlier or the four minutes > > with the previous patch. > > Are you using the patches I just sent? Not yet, I was still busy with the older version, and trying to figure out exactly what went wrong in ld.bfd. FWIW, I first tried to see if the hash tables were just too small, but as it turned out that was not the problem. When I tried to change the default hash table sizes, making them bigger only made things slower. I also found the --hash-size=xxx option, which has a significant impact on runtime speed. Interestingly again, using sizes less than the default made things faster in practice. If we can work out the optimum size for the kernel build, that might shave a few minutes off the total build time. > Either way, you also need > to do the same for data and bss sections as you are using > -fdata-sections too. Right. > I've found virtually no build time regression on powerpc or x86 > when those are taken care of properly (x86 numbers I sent are typo, > it's not 5m20, it's 5m02). Interesting. I wonder if it's got something to do with the generation of the branch trampolines on ARM, as we have a lot of them on an allyesconfig. Is the 5m20 the total build time for the kernel, the time for rebuilding after a trivial change, or the time to call 'ld.bfd' once? Are you using ld.bfd on x86 or ld.gold? For me ld.gold either works and is really fast, or it crashes, depending on the configuration. I also don't think it supports big-endian ARM (which is what allyesconfig ends up using). Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Saturday, August 6, 2016 2:16:42 AM CEST Nicholas Piggin wrote: > > > > diff --git a/include/asm-generic/vmlinux.lds.h > > b/include/asm-generic/vmlinux.lds.h > > index 0ec807d69f18..7a3ad269fa23 100644 > > --- a/include/asm-generic/vmlinux.lds.h > > +++ b/include/asm-generic/vmlinux.lds.h > > @@ -433,7 +433,7 @@ > > * during second ld run in second ld pass when generating System.map */ > > #define TEXT_TEXT\ > > ALIGN_FUNCTION(); \ > > - *(.text.hot .text .text.fixup .text.unlikely) \ > > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > > *(.ref.text)\ > > MEM_KEEP(init.text) \ > > MEM_KEEP(exit.text) \ > > > > > > It also got much faster again, the link time for an allyesconfig > > kernel is now 18 minutes instead of 10 hours, but it's still > > much worse than the 2 minutes I had earlier or the four minutes > > with the previous patch. > > Are you using the patches I just sent? Not yet, I was still busy with the older version, and trying to figure out exactly what went wrong in ld.bfd. FWIW, I first tried to see if the hash tables were just too small, but as it turned out that was not the problem. When I tried to change the default hash table sizes, making them bigger only made things slower. I also found the --hash-size=xxx option, which has a significant impact on runtime speed. Interestingly again, using sizes less than the default made things faster in practice. If we can work out the optimum size for the kernel build, that might shave a few minutes off the total build time. > Either way, you also need > to do the same for data and bss sections as you are using > -fdata-sections too. Right. > I've found virtually no build time regression on powerpc or x86 > when those are taken care of properly (x86 numbers I sent are typo, > it's not 5m20, it's 5m02). Interesting. I wonder if it's got something to do with the generation of the branch trampolines on ARM, as we have a lot of them on an allyesconfig. Is the 5m20 the total build time for the kernel, the time for rebuilding after a trivial change, or the time to call 'ld.bfd' once? Are you using ld.bfd on x86 or ld.gold? For me ld.gold either works and is really fast, or it crashes, depending on the configuration. I also don't think it supports big-endian ARM (which is what allyesconfig ends up using). Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Fri, 05 Aug 2016 18:01:13 +0200 Arnd Bergmannwrote: > On Friday, August 5, 2016 10:26:25 PM CEST Nicholas Piggin wrote: > > On Fri, 05 Aug 2016 12:17:27 +0200 > > Arnd Bergmann wrote: > > > > and I also get link errors for the .text.fixup section > > > for any users of __put_user() in really large kernels: > > > net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to > > > fit: R_ARM_JUMP24 against `.text.batadv_log_read' > > > > This may be fixed by fixing the linker script to bring in the new > > sections properly (see new patchset). > > > > If not, then if you can combine the sections rather than have them > > consecutive in the output, e.g.,: > > > > *(.text .text.fixup) > > > > Rather than > > > > *(.text) > > *(.text.fixup) > > > > Then the linker has more freedom to rearrange them. I realize it's > > not that simple with ARM's .text.fixup, but maybe that helps you > > get it to work. > > This did the trick: > > diff --git a/include/asm-generic/vmlinux.lds.h > b/include/asm-generic/vmlinux.lds.h > index 0ec807d69f18..7a3ad269fa23 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -433,7 +433,7 @@ > * during second ld run in second ld pass when generating System.map */ > #define TEXT_TEXT\ > ALIGN_FUNCTION(); \ > - *(.text.hot .text .text.fixup .text.unlikely) \ > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > *(.ref.text)\ > MEM_KEEP(init.text) \ > MEM_KEEP(exit.text) \ > > > It also got much faster again, the link time for an allyesconfig > kernel is now 18 minutes instead of 10 hours, but it's still > much worse than the 2 minutes I had earlier or the four minutes > with the previous patch. Are you using the patches I just sent? Either way, you also need to do the same for data and bss sections as you are using -fdata-sections too. I've found virtually no build time regression on powerpc or x86 when those are taken care of properly (x86 numbers I sent are typo, it's not 5m20, it's 5m02). Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Fri, 05 Aug 2016 18:01:13 +0200 Arnd Bergmann wrote: > On Friday, August 5, 2016 10:26:25 PM CEST Nicholas Piggin wrote: > > On Fri, 05 Aug 2016 12:17:27 +0200 > > Arnd Bergmann wrote: > > > > and I also get link errors for the .text.fixup section > > > for any users of __put_user() in really large kernels: > > > net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to > > > fit: R_ARM_JUMP24 against `.text.batadv_log_read' > > > > This may be fixed by fixing the linker script to bring in the new > > sections properly (see new patchset). > > > > If not, then if you can combine the sections rather than have them > > consecutive in the output, e.g.,: > > > > *(.text .text.fixup) > > > > Rather than > > > > *(.text) > > *(.text.fixup) > > > > Then the linker has more freedom to rearrange them. I realize it's > > not that simple with ARM's .text.fixup, but maybe that helps you > > get it to work. > > This did the trick: > > diff --git a/include/asm-generic/vmlinux.lds.h > b/include/asm-generic/vmlinux.lds.h > index 0ec807d69f18..7a3ad269fa23 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -433,7 +433,7 @@ > * during second ld run in second ld pass when generating System.map */ > #define TEXT_TEXT\ > ALIGN_FUNCTION(); \ > - *(.text.hot .text .text.fixup .text.unlikely) \ > + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ > *(.ref.text)\ > MEM_KEEP(init.text) \ > MEM_KEEP(exit.text) \ > > > It also got much faster again, the link time for an allyesconfig > kernel is now 18 minutes instead of 10 hours, but it's still > much worse than the 2 minutes I had earlier or the four minutes > with the previous patch. Are you using the patches I just sent? Either way, you also need to do the same for data and bss sections as you are using -fdata-sections too. I've found virtually no build time regression on powerpc or x86 when those are taken care of properly (x86 numbers I sent are typo, it's not 5m20, it's 5m02). Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Friday, August 5, 2016 10:26:25 PM CEST Nicholas Piggin wrote: > On Fri, 05 Aug 2016 12:17:27 +0200 > Arnd Bergmannwrote: > > and I also get link errors for the .text.fixup section > > for any users of __put_user() in really large kernels: > > net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to fit: > > R_ARM_JUMP24 against `.text.batadv_log_read' > > This may be fixed by fixing the linker script to bring in the new > sections properly (see new patchset). > > If not, then if you can combine the sections rather than have them > consecutive in the output, e.g.,: > > *(.text .text.fixup) > > Rather than > > *(.text) > *(.text.fixup) > > Then the linker has more freedom to rearrange them. I realize it's > not that simple with ARM's .text.fixup, but maybe that helps you > get it to work. This did the trick: diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 0ec807d69f18..7a3ad269fa23 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -433,7 +433,7 @@ * during second ld run in second ld pass when generating System.map */ #define TEXT_TEXT \ ALIGN_FUNCTION(); \ - *(.text.hot .text .text.fixup .text.unlikely) \ + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ *(.ref.text)\ MEM_KEEP(init.text) \ MEM_KEEP(exit.text) \ It also got much faster again, the link time for an allyesconfig kernel is now 18 minutes instead of 10 hours, but it's still much worse than the 2 minutes I had earlier or the four minutes with the previous patch. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Friday, August 5, 2016 10:26:25 PM CEST Nicholas Piggin wrote: > On Fri, 05 Aug 2016 12:17:27 +0200 > Arnd Bergmann wrote: > > and I also get link errors for the .text.fixup section > > for any users of __put_user() in really large kernels: > > net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to fit: > > R_ARM_JUMP24 against `.text.batadv_log_read' > > This may be fixed by fixing the linker script to bring in the new > sections properly (see new patchset). > > If not, then if you can combine the sections rather than have them > consecutive in the output, e.g.,: > > *(.text .text.fixup) > > Rather than > > *(.text) > *(.text.fixup) > > Then the linker has more freedom to rearrange them. I realize it's > not that simple with ARM's .text.fixup, but maybe that helps you > get it to work. This did the trick: diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 0ec807d69f18..7a3ad269fa23 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -433,7 +433,7 @@ * during second ld run in second ld pass when generating System.map */ #define TEXT_TEXT \ ALIGN_FUNCTION(); \ - *(.text.hot .text .text.fixup .text.unlikely) \ + *(.text.hot .text .text.* .text.fixup .text.unlikely) \ *(.ref.text)\ MEM_KEEP(init.text) \ MEM_KEEP(exit.text) \ It also got much faster again, the link time for an allyesconfig kernel is now 18 minutes instead of 10 hours, but it's still much worse than the 2 minutes I had earlier or the four minutes with the previous patch. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Fri, 05 Aug 2016 12:17:27 +0200 Arnd Bergmannwrote: > On Friday, August 5, 2016 6:41:08 PM CEST Nicholas Piggin wrote: > > On Thu, 4 Aug 2016 12:06:41 -0500 > > Segher Boessenkool wrote: > > > > > On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > > > > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > > > > > > > + __used \ > > > > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), > > > > > used)) \ > > > > > > > > > > > > I've just started testing this, but the first problem I ran into > > > > is that @ and # are special characters that have an architecture > > > > specific meaning to the assembler. On ARM, you need "%note @" instead > > > > of "@note #". > > > > > > That comment trick (I still feel guilty about it) causes more problems > > > than it solves. Please don't try to use it :-) > > > > Yeah that's a funny hack. I don't think it's required though, but I'm just > > running through some more tests. > > > > I think I found an improvement with the thin archives as well -- we were > > still building symbol table after removing the s option (that only avoids > > index). "S" is required to not build symbol table. > > > > I'll send out an RFC on a slightly more polished patch series shortly. > > > I could not find Nico's patches, but based on the information in his > presentation at > > https://www.linuxplumbersconf.org/2015/ocw//system/presentations/3369/original/slides.html#(1) > > I created a patch for ARM that mirrors what you have for powerpc, see > below. Great, thanks for jumping in. I posted another set which is a lot improved you should pick up. > I have successfully built normal-sized kernels with this (not tried > running them). Unfortunately, the build time for "allyesconfig" > kernel explodes, the final link time is now in the hours instead of > minutes (no exact numbers unfortunately, it takes too long to > reproduce), That's becase we need to coalesce the new sections properly into the output file. binutils does not cope with vast number of sections in final linked file and spends all its time in hash lookup then explodes usually. > and I also get link errors for the .text.fixup section > for any users of __put_user() in really large kernels: > net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to fit: > R_ARM_JUMP24 against `.text.batadv_log_read' This may be fixed by fixing the linker script to bring in the new sections properly (see new patchset). If not, then if you can combine the sections rather than have them consecutive in the output, e.g.,: *(.text .text.fixup) Rather than *(.text) *(.text.fixup) Then the linker has more freedom to rearrange them. I realize it's not that simple with ARM's .text.fixup, but maybe that helps you get it to work. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Fri, 05 Aug 2016 12:17:27 +0200 Arnd Bergmann wrote: > On Friday, August 5, 2016 6:41:08 PM CEST Nicholas Piggin wrote: > > On Thu, 4 Aug 2016 12:06:41 -0500 > > Segher Boessenkool wrote: > > > > > On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > > > > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > > > > > > > + __used \ > > > > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), > > > > > used)) \ > > > > > > > > > > > > I've just started testing this, but the first problem I ran into > > > > is that @ and # are special characters that have an architecture > > > > specific meaning to the assembler. On ARM, you need "%note @" instead > > > > of "@note #". > > > > > > That comment trick (I still feel guilty about it) causes more problems > > > than it solves. Please don't try to use it :-) > > > > Yeah that's a funny hack. I don't think it's required though, but I'm just > > running through some more tests. > > > > I think I found an improvement with the thin archives as well -- we were > > still building symbol table after removing the s option (that only avoids > > index). "S" is required to not build symbol table. > > > > I'll send out an RFC on a slightly more polished patch series shortly. > > > I could not find Nico's patches, but based on the information in his > presentation at > > https://www.linuxplumbersconf.org/2015/ocw//system/presentations/3369/original/slides.html#(1) > > I created a patch for ARM that mirrors what you have for powerpc, see > below. Great, thanks for jumping in. I posted another set which is a lot improved you should pick up. > I have successfully built normal-sized kernels with this (not tried > running them). Unfortunately, the build time for "allyesconfig" > kernel explodes, the final link time is now in the hours instead of > minutes (no exact numbers unfortunately, it takes too long to > reproduce), That's becase we need to coalesce the new sections properly into the output file. binutils does not cope with vast number of sections in final linked file and spends all its time in hash lookup then explodes usually. > and I also get link errors for the .text.fixup section > for any users of __put_user() in really large kernels: > net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to fit: > R_ARM_JUMP24 against `.text.batadv_log_read' This may be fixed by fixing the linker script to bring in the new sections properly (see new patchset). If not, then if you can combine the sections rather than have them consecutive in the output, e.g.,: *(.text .text.fixup) Rather than *(.text) *(.text.fixup) Then the linker has more freedom to rearrange them. I realize it's not that simple with ARM's .text.fixup, but maybe that helps you get it to work. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Friday, August 5, 2016 6:41:08 PM CEST Nicholas Piggin wrote: > On Thu, 4 Aug 2016 12:06:41 -0500 > Segher Boessenkoolwrote: > > > On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > > > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > > > > > + __used \ > > > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), > > > > used)) \ > > > > > > > > > I've just started testing this, but the first problem I ran into > > > is that @ and # are special characters that have an architecture > > > specific meaning to the assembler. On ARM, you need "%note @" instead > > > of "@note #". > > > > That comment trick (I still feel guilty about it) causes more problems > > than it solves. Please don't try to use it :-) > > Yeah that's a funny hack. I don't think it's required though, but I'm just > running through some more tests. > > I think I found an improvement with the thin archives as well -- we were > still building symbol table after removing the s option (that only avoids > index). "S" is required to not build symbol table. > > I'll send out an RFC on a slightly more polished patch series shortly. I could not find Nico's patches, but based on the information in his presentation at https://www.linuxplumbersconf.org/2015/ocw//system/presentations/3369/original/slides.html#(1) I created a patch for ARM that mirrors what you have for powerpc, see below. I have successfully built normal-sized kernels with this (not tried running them). Unfortunately, the build time for "allyesconfig" kernel explodes, the final link time is now in the hours instead of minutes (no exact numbers unfortunately, it takes too long to reproduce), and I also get link errors for the .text.fixup section for any users of __put_user() in really large kernels: net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to fit: R_ARM_JUMP24 against `.text.batadv_log_read' ... drivers/scsi/sg.o:(.text.fixup+0x4): relocation truncated to fit: R_ARM_THM_JUMP24 against `.text.sg_ioctl' drivers/scsi/sg.o:(.text.fixup+0xc): relocation truncated to fit: R_ARM_THM_JUMP24 against `.text.sg_ioctl' drivers/scsi/sg.o:(.text.fixup+0x14): relocation truncated to fit: R_ARM_THM_JUMP24 against `.text.sg_ioctl' ... This originates from #define __put_user_asm(x, __pu_addr, err, instr)\ __asm__ __volatile__( \ "1: " TUSER(instr) " %1, [%2], #0\n"\ "2:\n" \ " .pushsection .text.fixup,\"ax\"\n" \ " .align 2\n"\ "3: mov %0, %3\n" \ " b 2b\n" \ " .popsection\n" \ " .pushsection __ex_table,\"a\"\n"\ " .align 3\n"\ " .long 1b, 3b\n" \ " .popsection"\ : "+r" (err)\ : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ : "cc") Arnd diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 842f46af5b9d..b4fc91603429 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -362,6 +362,8 @@ archclean: # My testing targets (bypasses dependencies) bp:; $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/bootpImage +KBUILD_CFLAGS += -ffunction-sections -fdata-sections +LDFLAGS_vmlinux+= --gc-sections define archhelp echo '* zImage- Compressed kernel image (arch/$(ARCH)/boot/zImage)' diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index ad325a8c7e1e..f0eca9a96005 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -11,6 +11,9 @@ CFLAGS_REMOVE_insn.o = -pg CFLAGS_REMOVE_patch.o = -pg endif +ccflags-y += -fno-function-sections -fno-data-sections +subdir-ccflags-y += -fno-function-sections -fno-data-sections + CFLAGS_REMOVE_return_address.o = -pg # Object file lists. diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S index 56c8bdf776bd..ef7d8d7a997b 100644 --- a/arch/arm/kernel/vmlinux-xip.lds.S +++ b/arch/arm/kernel/vmlinux-xip.lds.S @@ -12,17 +12,17 @@ #define PROC_INFO \ . = ALIGN(4); \ VMLINUX_SYMBOL(__proc_info_begin) = .; \ - *(.proc.info.init) \ + KEEP(*(.proc.info.init))\ VMLINUX_SYMBOL(__proc_info_end) = .;
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Friday, August 5, 2016 6:41:08 PM CEST Nicholas Piggin wrote: > On Thu, 4 Aug 2016 12:06:41 -0500 > Segher Boessenkool wrote: > > > On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > > > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > > > > > + __used \ > > > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), > > > > used)) \ > > > > > > > > > I've just started testing this, but the first problem I ran into > > > is that @ and # are special characters that have an architecture > > > specific meaning to the assembler. On ARM, you need "%note @" instead > > > of "@note #". > > > > That comment trick (I still feel guilty about it) causes more problems > > than it solves. Please don't try to use it :-) > > Yeah that's a funny hack. I don't think it's required though, but I'm just > running through some more tests. > > I think I found an improvement with the thin archives as well -- we were > still building symbol table after removing the s option (that only avoids > index). "S" is required to not build symbol table. > > I'll send out an RFC on a slightly more polished patch series shortly. I could not find Nico's patches, but based on the information in his presentation at https://www.linuxplumbersconf.org/2015/ocw//system/presentations/3369/original/slides.html#(1) I created a patch for ARM that mirrors what you have for powerpc, see below. I have successfully built normal-sized kernels with this (not tried running them). Unfortunately, the build time for "allyesconfig" kernel explodes, the final link time is now in the hours instead of minutes (no exact numbers unfortunately, it takes too long to reproduce), and I also get link errors for the .text.fixup section for any users of __put_user() in really large kernels: net/batman-adv/batman-adv.o:(.text.fixup+0x4): relocation truncated to fit: R_ARM_JUMP24 against `.text.batadv_log_read' ... drivers/scsi/sg.o:(.text.fixup+0x4): relocation truncated to fit: R_ARM_THM_JUMP24 against `.text.sg_ioctl' drivers/scsi/sg.o:(.text.fixup+0xc): relocation truncated to fit: R_ARM_THM_JUMP24 against `.text.sg_ioctl' drivers/scsi/sg.o:(.text.fixup+0x14): relocation truncated to fit: R_ARM_THM_JUMP24 against `.text.sg_ioctl' ... This originates from #define __put_user_asm(x, __pu_addr, err, instr)\ __asm__ __volatile__( \ "1: " TUSER(instr) " %1, [%2], #0\n"\ "2:\n" \ " .pushsection .text.fixup,\"ax\"\n" \ " .align 2\n"\ "3: mov %0, %3\n" \ " b 2b\n" \ " .popsection\n" \ " .pushsection __ex_table,\"a\"\n"\ " .align 3\n"\ " .long 1b, 3b\n" \ " .popsection"\ : "+r" (err)\ : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ : "cc") Arnd diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 842f46af5b9d..b4fc91603429 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -362,6 +362,8 @@ archclean: # My testing targets (bypasses dependencies) bp:; $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/bootpImage +KBUILD_CFLAGS += -ffunction-sections -fdata-sections +LDFLAGS_vmlinux+= --gc-sections define archhelp echo '* zImage- Compressed kernel image (arch/$(ARCH)/boot/zImage)' diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index ad325a8c7e1e..f0eca9a96005 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -11,6 +11,9 @@ CFLAGS_REMOVE_insn.o = -pg CFLAGS_REMOVE_patch.o = -pg endif +ccflags-y += -fno-function-sections -fno-data-sections +subdir-ccflags-y += -fno-function-sections -fno-data-sections + CFLAGS_REMOVE_return_address.o = -pg # Object file lists. diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S index 56c8bdf776bd..ef7d8d7a997b 100644 --- a/arch/arm/kernel/vmlinux-xip.lds.S +++ b/arch/arm/kernel/vmlinux-xip.lds.S @@ -12,17 +12,17 @@ #define PROC_INFO \ . = ALIGN(4); \ VMLINUX_SYMBOL(__proc_info_begin) = .; \ - *(.proc.info.init) \ + KEEP(*(.proc.info.init))\ VMLINUX_SYMBOL(__proc_info_end) = .; #define IDMAP_TEXT
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 4 Aug 2016 12:06:41 -0500 Segher Boessenkoolwrote: > On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > > > + __used \ > > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), used)) \ > > > > > > > > > I've just started testing this, but the first problem I ran into > > is that @ and # are special characters that have an architecture > > specific meaning to the assembler. On ARM, you need "%note @" instead > > of "@note #". > > That comment trick (I still feel guilty about it) causes more problems > than it solves. Please don't try to use it :-) Yeah that's a funny hack. I don't think it's required though, but I'm just running through some more tests. I think I found an improvement with the thin archives as well -- we were still building symbol table after removing the s option (that only avoids index). "S" is required to not build symbol table. I'll send out an RFC on a slightly more polished patch series shortly. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 4 Aug 2016 12:06:41 -0500 Segher Boessenkool wrote: > On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > > > + __used \ > > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), used)) \ > > > > > > > > > I've just started testing this, but the first problem I ran into > > is that @ and # are special characters that have an architecture > > specific meaning to the assembler. On ARM, you need "%note @" instead > > of "@note #". > > That comment trick (I still feel guilty about it) causes more problems > than it solves. Please don't try to use it :-) Yeah that's a funny hack. I don't think it's required though, but I'm just running through some more tests. I think I found an improvement with the thin archives as well -- we were still building symbol table after removing the s option (that only avoids index). "S" is required to not build symbol table. I'll send out an RFC on a slightly more polished patch series shortly. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > + __used \ > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), used)) \ > > > I've just started testing this, but the first problem I ran into > is that @ and # are special characters that have an architecture > specific meaning to the assembler. On ARM, you need "%note @" instead > of "@note #". That comment trick (I still feel guilty about it) causes more problems than it solves. Please don't try to use it :-) Segher
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, Aug 04, 2016 at 06:10:57PM +0200, Arnd Bergmann wrote: > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > > + __used \ > > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), used)) \ > > > I've just started testing this, but the first problem I ran into > is that @ and # are special characters that have an architecture > specific meaning to the assembler. On ARM, you need "%note @" instead > of "@note #". That comment trick (I still feel guilty about it) causes more problems than it solves. Please don't try to use it :-) Segher
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > + __used \ > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), used)) \ I've just started testing this, but the first problem I ran into is that @ and # are special characters that have an architecture specific meaning to the assembler. On ARM, you need "%note @" instead of "@note #". Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > + __used \ > + __attribute__((section("___kentry" "+" #sym ",\"a\",@note #"), used)) \ I've just started testing this, but the first problem I ran into is that @ and # are special characters that have an architecture specific meaning to the assembler. On ARM, you need "%note @" instead of "@note #". Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 4 Aug 2016 22:31:39 +1000 Nicholas Pigginwrote: > On Thu, 04 Aug 2016 14:09:02 +0200 > Arnd Bergmann wrote: > > Nicolas Pitre has done some related work, adding him to Cc. IIRC we have > > actually had multiple implementations of -ffunction-sections/--gc-sections > > in the past that people have used in production, but none of them > > ever made it upstream. After some googling around it seems lto has been difficult to get in and it was agreed this gc-sections should be done first anyway (although it may indeed provide a superset of DCE, but it's always going to be more costly and complicated). Lto would have the same issue with liveness of entry points, which is really the only thing you need change in the kernel as far as I can see. I didn't really see what problems people were having with it though, so maybe it's architecture specific or something I haven't run into yet. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 4 Aug 2016 22:31:39 +1000 Nicholas Piggin wrote: > On Thu, 04 Aug 2016 14:09:02 +0200 > Arnd Bergmann wrote: > > Nicolas Pitre has done some related work, adding him to Cc. IIRC we have > > actually had multiple implementations of -ffunction-sections/--gc-sections > > in the past that people have used in production, but none of them > > ever made it upstream. After some googling around it seems lto has been difficult to get in and it was agreed this gc-sections should be done first anyway (although it may indeed provide a superset of DCE, but it's always going to be more costly and complicated). Lto would have the same issue with liveness of entry points, which is really the only thing you need change in the kernel as far as I can see. I didn't really see what problems people were having with it though, so maybe it's architecture specific or something I haven't run into yet. Thanks, Nick
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 11:54:18 PM CEST Nicholas Piggin wrote: > On Thu, 4 Aug 2016 22:31:39 +1000 > Nicholas Pigginwrote: > > On Thu, 04 Aug 2016 14:09:02 +0200 > > Arnd Bergmann wrote: > > > Nicolas Pitre has done some related work, adding him to Cc. IIRC we have > > > actually had multiple implementations of -ffunction-sections/--gc-sections > > > in the past that people have used in production, but none of them > > > ever made it upstream. > > After some googling around it seems lto has been difficult to > get in and it was agreed this gc-sections should be done first > anyway (although it may indeed provide a superset of DCE, but > it's always going to be more costly and complicated). Lto would > have the same issue with liveness of entry points, which is > really the only thing you need change in the kernel as far as I > can see. Ok, good. > I didn't really see what problems people were having with it > though, so maybe it's architecture specific or something I > haven't run into yet. I remember trying it a few years ago without success, it's possible that old binutils versions were more problematic. I'm happy to test your patches on ARM, with my randconfig builder I tend to find obscure bugs in corner cases that you might not normally find with just defconfig/allmodconfig builds. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 11:54:18 PM CEST Nicholas Piggin wrote: > On Thu, 4 Aug 2016 22:31:39 +1000 > Nicholas Piggin wrote: > > On Thu, 04 Aug 2016 14:09:02 +0200 > > Arnd Bergmann wrote: > > > Nicolas Pitre has done some related work, adding him to Cc. IIRC we have > > > actually had multiple implementations of -ffunction-sections/--gc-sections > > > in the past that people have used in production, but none of them > > > ever made it upstream. > > After some googling around it seems lto has been difficult to > get in and it was agreed this gc-sections should be done first > anyway (although it may indeed provide a superset of DCE, but > it's always going to be more costly and complicated). Lto would > have the same issue with liveness of entry points, which is > really the only thing you need change in the kernel as far as I > can see. Ok, good. > I didn't really see what problems people were having with it > though, so maybe it's architecture specific or something I > haven't run into yet. I remember trying it a few years ago without success, it's possible that old binutils versions were more problematic. I'm happy to test your patches on ARM, with my randconfig builder I tend to find obscure bugs in corner cases that you might not normally find with just defconfig/allmodconfig builds. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 04 Aug 2016 14:09:02 +0200 Arnd Bergmannwrote: > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > On Thu, 04 Aug 2016 12:37:41 +0200 Arnd Bergmann wrote: > > > On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > > > > I tried this > > > > > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > > > index b5e40ed86e60..89bca1a25916 100755 > > > > --- a/scripts/link-vmlinux.sh > > > > +++ b/scripts/link-vmlinux.sh > > > > @@ -44,7 +44,7 @@ modpost_link() > > > > local objects > > > > > > > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > > > > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > > > > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > > > > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > > > > else > > > > objects="${KBUILD_VMLINUX_INIT} --start-group > > > > ${KBUILD_VMLINUX_MAIN} --end-group" > > > > fi > > > > > > > > but that did not seem to change anything, the extra symbols are > > > > still there. I have not tried to understand what that actually > > > > does, so maybe I misunderstood your suggestion. > > > > > > > > > > On a second attempt, I did the same change for vmlinux instead of the > > > module (d'oh), and got a link failure instead: > > > > > > > > > arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': > > > (.text+0x3d4): undefined reference to `cpu_resume_mmu' > > > arch/arm/kernel/setup.o: In function `setup_arch': > > > ... > > > > > > However, I also see a link failure in some rare configurations > > > with just your patch: > > > > > > arch/arm/lib/lib.a(io-acorn.o): In function `outsl': > > > (.text+0x38): undefined reference to `printk' > > > > > > The problem being a file in a library object that is not referenced, > > > but that references another symbol that is not defined > > > (CONFIG_PRINTK=n). > > > > The first problem is the existing link system is buggy. I think an > > unconditional switch to --whole-archive (at least for modular kernels) > > should probably be done anyway. For example, on powerpc when building > > with --whole-archive, I have: > > > > +dma_noop_alloc > > +dma_noop_free > > +dma_noop_map_page > > +dma_noop_mapping_error > > +dma_noop_map_sg > > +dma_noop_ops > > +dma_noop_supported > > +fdt_add_reservemap_entry > > +fdt_begin_node > > +fdt_create > > +fdt_create_empty_tree > > +fdt_end_node > > +fdt_errtable > > +find_cpio_data > > +ioremap_page_range > > > > find_cpio_data is unnecessary and it's a codesize regression to link it. > > But dma_noop_ops and ioremap_page_range are exported symbols. If I > > reference dma_noop_ops from some random module with otherwise unpatched > > kernel: > > > > ERROR: "dma_noop_ops" [drivers/char/bsr.ko] undefined! > > Right, but only on s390, which is the one architecture using this. > I think we should just have a Kconfig symbol for this file that > gets selected by any architecture that needs it. No, the problem is that the module is being selected and built but it is missing from the vmlinux despite being exported. > This is also what we have ended up doing for almost all other > files in lib/ > > > The real problem is that our linkage requirements are like a shared > > library when we build modular. > > > > We could build a list of exports and make it link objects with those > > symbols, to solve this, but IMO that's just wasting lipstick on a pig. > > But I will to propose a patch to always use --whole-archive, thin > > archives or not, and transition all archs over to it in a few release > > cycles. It just works by luck right now. > > > > Why is it a pig? Because having the linker to notice no external > > references and just skipping the .o completely is trying to use a hammer > > as a scalpel. It's just not a very effective way to eliminate dead code > > -- I pulled in only a handful of unneeded functions by switching it. > > If we do that, we may just as well get rid of $(lib-y) in the process and > always use $(obj-y). Sure, after we switch everybody over. > > I mean it is a quick simple feature that probably works well enough with > > simple build systems. But not an advanced one that builds almost > > everything on demand and also has loadable modules and must act like a > > shared library. > > > > Real linker DCE is a valid optimisation that can't be replaced by the > > build system of course, but we need to do it properly. Here's what I'm > > working on. > > > > It applies on top of the previous patch I sent, plus some powerpc stuff > > I'm working on that you should be able to just ignore for another arch. > > it's a WIP, but if you can see if it works for arm that would be cool. > > > > It doesn't actually build allyesconfig after this, > > ld: .tmp_vmlinux1: Too many sections: 220655 (>= 65280) > > > > But on a more reasonable configuration (ppc64le) > > text
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 04 Aug 2016 14:09:02 +0200 Arnd Bergmann wrote: > On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > > On Thu, 04 Aug 2016 12:37:41 +0200 Arnd Bergmann wrote: > > > On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > > > > I tried this > > > > > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > > > index b5e40ed86e60..89bca1a25916 100755 > > > > --- a/scripts/link-vmlinux.sh > > > > +++ b/scripts/link-vmlinux.sh > > > > @@ -44,7 +44,7 @@ modpost_link() > > > > local objects > > > > > > > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > > > > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > > > > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > > > > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > > > > else > > > > objects="${KBUILD_VMLINUX_INIT} --start-group > > > > ${KBUILD_VMLINUX_MAIN} --end-group" > > > > fi > > > > > > > > but that did not seem to change anything, the extra symbols are > > > > still there. I have not tried to understand what that actually > > > > does, so maybe I misunderstood your suggestion. > > > > > > > > > > On a second attempt, I did the same change for vmlinux instead of the > > > module (d'oh), and got a link failure instead: > > > > > > > > > arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': > > > (.text+0x3d4): undefined reference to `cpu_resume_mmu' > > > arch/arm/kernel/setup.o: In function `setup_arch': > > > ... > > > > > > However, I also see a link failure in some rare configurations > > > with just your patch: > > > > > > arch/arm/lib/lib.a(io-acorn.o): In function `outsl': > > > (.text+0x38): undefined reference to `printk' > > > > > > The problem being a file in a library object that is not referenced, > > > but that references another symbol that is not defined > > > (CONFIG_PRINTK=n). > > > > The first problem is the existing link system is buggy. I think an > > unconditional switch to --whole-archive (at least for modular kernels) > > should probably be done anyway. For example, on powerpc when building > > with --whole-archive, I have: > > > > +dma_noop_alloc > > +dma_noop_free > > +dma_noop_map_page > > +dma_noop_mapping_error > > +dma_noop_map_sg > > +dma_noop_ops > > +dma_noop_supported > > +fdt_add_reservemap_entry > > +fdt_begin_node > > +fdt_create > > +fdt_create_empty_tree > > +fdt_end_node > > +fdt_errtable > > +find_cpio_data > > +ioremap_page_range > > > > find_cpio_data is unnecessary and it's a codesize regression to link it. > > But dma_noop_ops and ioremap_page_range are exported symbols. If I > > reference dma_noop_ops from some random module with otherwise unpatched > > kernel: > > > > ERROR: "dma_noop_ops" [drivers/char/bsr.ko] undefined! > > Right, but only on s390, which is the one architecture using this. > I think we should just have a Kconfig symbol for this file that > gets selected by any architecture that needs it. No, the problem is that the module is being selected and built but it is missing from the vmlinux despite being exported. > This is also what we have ended up doing for almost all other > files in lib/ > > > The real problem is that our linkage requirements are like a shared > > library when we build modular. > > > > We could build a list of exports and make it link objects with those > > symbols, to solve this, but IMO that's just wasting lipstick on a pig. > > But I will to propose a patch to always use --whole-archive, thin > > archives or not, and transition all archs over to it in a few release > > cycles. It just works by luck right now. > > > > Why is it a pig? Because having the linker to notice no external > > references and just skipping the .o completely is trying to use a hammer > > as a scalpel. It's just not a very effective way to eliminate dead code > > -- I pulled in only a handful of unneeded functions by switching it. > > If we do that, we may just as well get rid of $(lib-y) in the process and > always use $(obj-y). Sure, after we switch everybody over. > > I mean it is a quick simple feature that probably works well enough with > > simple build systems. But not an advanced one that builds almost > > everything on demand and also has loadable modules and must act like a > > shared library. > > > > Real linker DCE is a valid optimisation that can't be replaced by the > > build system of course, but we need to do it properly. Here's what I'm > > working on. > > > > It applies on top of the previous patch I sent, plus some powerpc stuff > > I'm working on that you should be able to just ignore for another arch. > > it's a WIP, but if you can see if it works for arm that would be cool. > > > > It doesn't actually build allyesconfig after this, > > ld: .tmp_vmlinux1: Too many sections: 220655 (>= 65280) > > > > But on a more reasonable configuration (ppc64le) > > text data bss
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > On Thu, 04 Aug 2016 12:37:41 +0200 Arnd Bergmannwrote: > > On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > > > I tried this > > > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > > index b5e40ed86e60..89bca1a25916 100755 > > > --- a/scripts/link-vmlinux.sh > > > +++ b/scripts/link-vmlinux.sh > > > @@ -44,7 +44,7 @@ modpost_link() > > > local objects > > > > > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > > > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > > > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > > > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > > > else > > > objects="${KBUILD_VMLINUX_INIT} --start-group > > > ${KBUILD_VMLINUX_MAIN} --end-group" > > > fi > > > > > > but that did not seem to change anything, the extra symbols are > > > still there. I have not tried to understand what that actually > > > does, so maybe I misunderstood your suggestion. > > > > > > > On a second attempt, I did the same change for vmlinux instead of the > > module (d'oh), and got a link failure instead: > > > > > > arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': > > (.text+0x3d4): undefined reference to `cpu_resume_mmu' > > arch/arm/kernel/setup.o: In function `setup_arch': > > ... > > > > However, I also see a link failure in some rare configurations > > with just your patch: > > > > arch/arm/lib/lib.a(io-acorn.o): In function `outsl': > > (.text+0x38): undefined reference to `printk' > > > > The problem being a file in a library object that is not referenced, > > but that references another symbol that is not defined > > (CONFIG_PRINTK=n). > > The first problem is the existing link system is buggy. I think an > unconditional switch to --whole-archive (at least for modular kernels) > should probably be done anyway. For example, on powerpc when building > with --whole-archive, I have: > > +dma_noop_alloc > +dma_noop_free > +dma_noop_map_page > +dma_noop_mapping_error > +dma_noop_map_sg > +dma_noop_ops > +dma_noop_supported > +fdt_add_reservemap_entry > +fdt_begin_node > +fdt_create > +fdt_create_empty_tree > +fdt_end_node > +fdt_errtable > +find_cpio_data > +ioremap_page_range > > find_cpio_data is unnecessary and it's a codesize regression to link it. > But dma_noop_ops and ioremap_page_range are exported symbols. If I > reference dma_noop_ops from some random module with otherwise unpatched > kernel: > > ERROR: "dma_noop_ops" [drivers/char/bsr.ko] undefined! Right, but only on s390, which is the one architecture using this. I think we should just have a Kconfig symbol for this file that gets selected by any architecture that needs it. This is also what we have ended up doing for almost all other files in lib/ > The real problem is that our linkage requirements are like a shared > library when we build modular. > > We could build a list of exports and make it link objects with those > symbols, to solve this, but IMO that's just wasting lipstick on a pig. > But I will to propose a patch to always use --whole-archive, thin > archives or not, and transition all archs over to it in a few release > cycles. It just works by luck right now. > > Why is it a pig? Because having the linker to notice no external > references and just skipping the .o completely is trying to use a hammer > as a scalpel. It's just not a very effective way to eliminate dead code > -- I pulled in only a handful of unneeded functions by switching it. If we do that, we may just as well get rid of $(lib-y) in the process and always use $(obj-y). > I mean it is a quick simple feature that probably works well enough with > simple build systems. But not an advanced one that builds almost > everything on demand and also has loadable modules and must act like a > shared library. > > Real linker DCE is a valid optimisation that can't be replaced by the > build system of course, but we need to do it properly. Here's what I'm > working on. > > It applies on top of the previous patch I sent, plus some powerpc stuff > I'm working on that you should be able to just ignore for another arch. > it's a WIP, but if you can see if it works for arm that would be cool. > > It doesn't actually build allyesconfig after this, > ld: .tmp_vmlinux1: Too many sections: 220655 (>= 65280) > > But on a more reasonable configuration (ppc64le) > text data bssdec filename > 11191672 1183536 1923820 14299028 vmlinux > 10625528861895 1919707 13407130 vmlinux.thin+gc > > 10M-552K 1M-314K ~ 13M-870K Nice! > And it actually boots too, which is fairly astounding considering that > it lost half a meg of code and 1/3 of its data. I'm not completely sure > I've not done something wrong... Nicolas Pitre has done some related work, adding him to Cc. IIRC we have
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 9:47:13 PM CEST Nicholas Piggin wrote: > On Thu, 04 Aug 2016 12:37:41 +0200 Arnd Bergmann wrote: > > On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > > > I tried this > > > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > > index b5e40ed86e60..89bca1a25916 100755 > > > --- a/scripts/link-vmlinux.sh > > > +++ b/scripts/link-vmlinux.sh > > > @@ -44,7 +44,7 @@ modpost_link() > > > local objects > > > > > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > > > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > > > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > > > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > > > else > > > objects="${KBUILD_VMLINUX_INIT} --start-group > > > ${KBUILD_VMLINUX_MAIN} --end-group" > > > fi > > > > > > but that did not seem to change anything, the extra symbols are > > > still there. I have not tried to understand what that actually > > > does, so maybe I misunderstood your suggestion. > > > > > > > On a second attempt, I did the same change for vmlinux instead of the > > module (d'oh), and got a link failure instead: > > > > > > arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': > > (.text+0x3d4): undefined reference to `cpu_resume_mmu' > > arch/arm/kernel/setup.o: In function `setup_arch': > > ... > > > > However, I also see a link failure in some rare configurations > > with just your patch: > > > > arch/arm/lib/lib.a(io-acorn.o): In function `outsl': > > (.text+0x38): undefined reference to `printk' > > > > The problem being a file in a library object that is not referenced, > > but that references another symbol that is not defined > > (CONFIG_PRINTK=n). > > The first problem is the existing link system is buggy. I think an > unconditional switch to --whole-archive (at least for modular kernels) > should probably be done anyway. For example, on powerpc when building > with --whole-archive, I have: > > +dma_noop_alloc > +dma_noop_free > +dma_noop_map_page > +dma_noop_mapping_error > +dma_noop_map_sg > +dma_noop_ops > +dma_noop_supported > +fdt_add_reservemap_entry > +fdt_begin_node > +fdt_create > +fdt_create_empty_tree > +fdt_end_node > +fdt_errtable > +find_cpio_data > +ioremap_page_range > > find_cpio_data is unnecessary and it's a codesize regression to link it. > But dma_noop_ops and ioremap_page_range are exported symbols. If I > reference dma_noop_ops from some random module with otherwise unpatched > kernel: > > ERROR: "dma_noop_ops" [drivers/char/bsr.ko] undefined! Right, but only on s390, which is the one architecture using this. I think we should just have a Kconfig symbol for this file that gets selected by any architecture that needs it. This is also what we have ended up doing for almost all other files in lib/ > The real problem is that our linkage requirements are like a shared > library when we build modular. > > We could build a list of exports and make it link objects with those > symbols, to solve this, but IMO that's just wasting lipstick on a pig. > But I will to propose a patch to always use --whole-archive, thin > archives or not, and transition all archs over to it in a few release > cycles. It just works by luck right now. > > Why is it a pig? Because having the linker to notice no external > references and just skipping the .o completely is trying to use a hammer > as a scalpel. It's just not a very effective way to eliminate dead code > -- I pulled in only a handful of unneeded functions by switching it. If we do that, we may just as well get rid of $(lib-y) in the process and always use $(obj-y). > I mean it is a quick simple feature that probably works well enough with > simple build systems. But not an advanced one that builds almost > everything on demand and also has loadable modules and must act like a > shared library. > > Real linker DCE is a valid optimisation that can't be replaced by the > build system of course, but we need to do it properly. Here's what I'm > working on. > > It applies on top of the previous patch I sent, plus some powerpc stuff > I'm working on that you should be able to just ignore for another arch. > it's a WIP, but if you can see if it works for arm that would be cool. > > It doesn't actually build allyesconfig after this, > ld: .tmp_vmlinux1: Too many sections: 220655 (>= 65280) > > But on a more reasonable configuration (ppc64le) > text data bssdec filename > 11191672 1183536 1923820 14299028 vmlinux > 10625528861895 1919707 13407130 vmlinux.thin+gc > > 10M-552K 1M-314K ~ 13M-870K Nice! > And it actually boots too, which is fairly astounding considering that > it lost half a meg of code and 1/3 of its data. I'm not completely sure > I've not done something wrong... Nicolas Pitre has done some related work, adding him to Cc. IIRC we have actually had
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 04 Aug 2016 12:37:41 +0200 Arnd Bergmannwrote: > On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > > I tried this > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index b5e40ed86e60..89bca1a25916 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -44,7 +44,7 @@ modpost_link() > > local objects > > > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > > else > > objects="${KBUILD_VMLINUX_INIT} --start-group > > ${KBUILD_VMLINUX_MAIN} --end-group" > > fi > > > > but that did not seem to change anything, the extra symbols are > > still there. I have not tried to understand what that actually > > does, so maybe I misunderstood your suggestion. > > > > On a second attempt, I did the same change for vmlinux instead of the > module (d'oh), and got a link failure instead: > > > arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': > (.text+0x3d4): undefined reference to `cpu_resume_mmu' > arch/arm/kernel/setup.o: In function `setup_arch': > setup.c:(.init.text+0x910): undefined reference to `init_uts_ns' > kernel/nsproxy.o:(.data+0x4): undefined reference to `init_uts_ns' > kernel/sched/core.o: In function `update_rq_clock': > core.c:(.text+0x6d8): undefined reference to `paravirt_steal_rq_enabled' > core.c:(.text+0x6dc): undefined reference to `pv_time_ops' > kernel/sched/cputime.o: In function `account_process_tick': > cputime.c:(.text+0x794): undefined reference to `paravirt_steal_enabled' > cputime.c:(.text+0x7a0): undefined reference to `pv_time_ops' > kernel/locking/lockdep.o: In function `save_trace': > lockdep.c:(.text+0xfe8): undefined reference to `save_stack_trace' > kernel/module.o: In function `load_module': > module.c:(.text+0x1b54): undefined reference to `elf_check_arch' > module.c:(.text+0x2024): undefined reference to `apply_relocate' > kernel/debug/debug_core.o: In function `kgdb_unregister_io_module': > debug_core.c:(.text+0x2e4): undefined reference to `kgdb_arch_exit' > kernel/debug/debug_core.o: In function `kgdb_arch_set_breakpoint': > debug_core.c:(.text+0x3bc): undefined reference to `arch_kgdb_ops' > kernel/debug/debug_core.o: In function `dbg_remove_all_break': > debug_core.c:(.text+0x6d0): undefined reference to `arch_kgdb_ops' > ... > > However, I also see a link failure in some rare configurations > with just your patch: > > arch/arm/lib/lib.a(io-acorn.o): In function `outsl': > (.text+0x38): undefined reference to `printk' > > The problem being a file in a library object that is not referenced, > but that references another symbol that is not defined > (CONFIG_PRINTK=n). The first problem is the existing link system is buggy. I think an unconditional switch to --whole-archive (at least for modular kernels) should probably be done anyway. For example, on powerpc when building with --whole-archive, I have: +dma_noop_alloc +dma_noop_free +dma_noop_map_page +dma_noop_mapping_error +dma_noop_map_sg +dma_noop_ops +dma_noop_supported +fdt_add_reservemap_entry +fdt_begin_node +fdt_create +fdt_create_empty_tree +fdt_end_node +fdt_errtable +find_cpio_data +ioremap_page_range find_cpio_data is unnecessary and it's a codesize regression to link it. But dma_noop_ops and ioremap_page_range are exported symbols. If I reference dma_noop_ops from some random module with otherwise unpatched kernel: ERROR: "dma_noop_ops" [drivers/char/bsr.ko] undefined! The real problem is that our linkage requirements are like a shared library when we build modular. We could build a list of exports and make it link objects with those symbols, to solve this, but IMO that's just wasting lipstick on a pig. But I will to propose a patch to always use --whole-archive, thin archives or not, and transition all archs over to it in a few release cycles. It just works by luck right now. Why is it a pig? Because having the linker to notice no external references and just skipping the .o completely is trying to use a hammer as a scalpel. It's just not a very effective way to eliminate dead code -- I pulled in only a handful of unneeded functions by switching it. I mean it is a quick simple feature that probably works well enough with simple build systems. But not an advanced one that builds almost everything on demand and also has loadable modules and must act like a shared library. Real linker DCE is a valid optimisation that can't be replaced by the build system of course, but we need to do it properly. Here's what I'm working on. It applies on top of the previous patch I sent, plus some powerpc stuff I'm working on that you should be able to just ignore for another arch. it's a WIP, but if you can see if it works for arm that would be cool. It doesn't actually
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thu, 04 Aug 2016 12:37:41 +0200 Arnd Bergmann wrote: > On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > > I tried this > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index b5e40ed86e60..89bca1a25916 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -44,7 +44,7 @@ modpost_link() > > local objects > > > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > > else > > objects="${KBUILD_VMLINUX_INIT} --start-group > > ${KBUILD_VMLINUX_MAIN} --end-group" > > fi > > > > but that did not seem to change anything, the extra symbols are > > still there. I have not tried to understand what that actually > > does, so maybe I misunderstood your suggestion. > > > > On a second attempt, I did the same change for vmlinux instead of the > module (d'oh), and got a link failure instead: > > > arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': > (.text+0x3d4): undefined reference to `cpu_resume_mmu' > arch/arm/kernel/setup.o: In function `setup_arch': > setup.c:(.init.text+0x910): undefined reference to `init_uts_ns' > kernel/nsproxy.o:(.data+0x4): undefined reference to `init_uts_ns' > kernel/sched/core.o: In function `update_rq_clock': > core.c:(.text+0x6d8): undefined reference to `paravirt_steal_rq_enabled' > core.c:(.text+0x6dc): undefined reference to `pv_time_ops' > kernel/sched/cputime.o: In function `account_process_tick': > cputime.c:(.text+0x794): undefined reference to `paravirt_steal_enabled' > cputime.c:(.text+0x7a0): undefined reference to `pv_time_ops' > kernel/locking/lockdep.o: In function `save_trace': > lockdep.c:(.text+0xfe8): undefined reference to `save_stack_trace' > kernel/module.o: In function `load_module': > module.c:(.text+0x1b54): undefined reference to `elf_check_arch' > module.c:(.text+0x2024): undefined reference to `apply_relocate' > kernel/debug/debug_core.o: In function `kgdb_unregister_io_module': > debug_core.c:(.text+0x2e4): undefined reference to `kgdb_arch_exit' > kernel/debug/debug_core.o: In function `kgdb_arch_set_breakpoint': > debug_core.c:(.text+0x3bc): undefined reference to `arch_kgdb_ops' > kernel/debug/debug_core.o: In function `dbg_remove_all_break': > debug_core.c:(.text+0x6d0): undefined reference to `arch_kgdb_ops' > ... > > However, I also see a link failure in some rare configurations > with just your patch: > > arch/arm/lib/lib.a(io-acorn.o): In function `outsl': > (.text+0x38): undefined reference to `printk' > > The problem being a file in a library object that is not referenced, > but that references another symbol that is not defined > (CONFIG_PRINTK=n). The first problem is the existing link system is buggy. I think an unconditional switch to --whole-archive (at least for modular kernels) should probably be done anyway. For example, on powerpc when building with --whole-archive, I have: +dma_noop_alloc +dma_noop_free +dma_noop_map_page +dma_noop_mapping_error +dma_noop_map_sg +dma_noop_ops +dma_noop_supported +fdt_add_reservemap_entry +fdt_begin_node +fdt_create +fdt_create_empty_tree +fdt_end_node +fdt_errtable +find_cpio_data +ioremap_page_range find_cpio_data is unnecessary and it's a codesize regression to link it. But dma_noop_ops and ioremap_page_range are exported symbols. If I reference dma_noop_ops from some random module with otherwise unpatched kernel: ERROR: "dma_noop_ops" [drivers/char/bsr.ko] undefined! The real problem is that our linkage requirements are like a shared library when we build modular. We could build a list of exports and make it link objects with those symbols, to solve this, but IMO that's just wasting lipstick on a pig. But I will to propose a patch to always use --whole-archive, thin archives or not, and transition all archs over to it in a few release cycles. It just works by luck right now. Why is it a pig? Because having the linker to notice no external references and just skipping the .o completely is trying to use a hammer as a scalpel. It's just not a very effective way to eliminate dead code -- I pulled in only a handful of unneeded functions by switching it. I mean it is a quick simple feature that probably works well enough with simple build systems. But not an advanced one that builds almost everything on demand and also has loadable modules and must act like a shared library. Real linker DCE is a valid optimisation that can't be replaced by the build system of course, but we need to do it properly. Here's what I'm working on. It applies on top of the previous patch I sent, plus some powerpc stuff I'm working on that you should be able to just ignore for another arch. it's a WIP, but if you can see if it works for arm that would be cool. It doesn't actually build
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > I tried this > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > index b5e40ed86e60..89bca1a25916 100755 > --- a/scripts/link-vmlinux.sh > +++ b/scripts/link-vmlinux.sh > @@ -44,7 +44,7 @@ modpost_link() > local objects > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > else > objects="${KBUILD_VMLINUX_INIT} --start-group > ${KBUILD_VMLINUX_MAIN} --end-group" > fi > > but that did not seem to change anything, the extra symbols are > still there. I have not tried to understand what that actually > does, so maybe I misunderstood your suggestion. > On a second attempt, I did the same change for vmlinux instead of the module (d'oh), and got a link failure instead: arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': (.text+0x3d4): undefined reference to `cpu_resume_mmu' arch/arm/kernel/setup.o: In function `setup_arch': setup.c:(.init.text+0x910): undefined reference to `init_uts_ns' kernel/nsproxy.o:(.data+0x4): undefined reference to `init_uts_ns' kernel/sched/core.o: In function `update_rq_clock': core.c:(.text+0x6d8): undefined reference to `paravirt_steal_rq_enabled' core.c:(.text+0x6dc): undefined reference to `pv_time_ops' kernel/sched/cputime.o: In function `account_process_tick': cputime.c:(.text+0x794): undefined reference to `paravirt_steal_enabled' cputime.c:(.text+0x7a0): undefined reference to `pv_time_ops' kernel/locking/lockdep.o: In function `save_trace': lockdep.c:(.text+0xfe8): undefined reference to `save_stack_trace' kernel/module.o: In function `load_module': module.c:(.text+0x1b54): undefined reference to `elf_check_arch' module.c:(.text+0x2024): undefined reference to `apply_relocate' kernel/debug/debug_core.o: In function `kgdb_unregister_io_module': debug_core.c:(.text+0x2e4): undefined reference to `kgdb_arch_exit' kernel/debug/debug_core.o: In function `kgdb_arch_set_breakpoint': debug_core.c:(.text+0x3bc): undefined reference to `arch_kgdb_ops' kernel/debug/debug_core.o: In function `dbg_remove_all_break': debug_core.c:(.text+0x6d0): undefined reference to `arch_kgdb_ops' ... However, I also see a link failure in some rare configurations with just your patch: arch/arm/lib/lib.a(io-acorn.o): In function `outsl': (.text+0x38): undefined reference to `printk' The problem being a file in a library object that is not referenced, but that references another symbol that is not defined (CONFIG_PRINTK=n). Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 11:00:49 AM CEST Arnd Bergmann wrote: > I tried this > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > index b5e40ed86e60..89bca1a25916 100755 > --- a/scripts/link-vmlinux.sh > +++ b/scripts/link-vmlinux.sh > @@ -44,7 +44,7 @@ modpost_link() > local objects > > if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then > - objects="--whole-archive ${KBUILD_VMLINUX_INIT} > ${KBUILD_VMLINUX_MAIN} --no-whole-archive" > + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" > else > objects="${KBUILD_VMLINUX_INIT} --start-group > ${KBUILD_VMLINUX_MAIN} --end-group" > fi > > but that did not seem to change anything, the extra symbols are > still there. I have not tried to understand what that actually > does, so maybe I misunderstood your suggestion. > On a second attempt, I did the same change for vmlinux instead of the module (d'oh), and got a link failure instead: arch/arm/mm/proc-xscale.o: In function `cpu_xscale_do_resume': (.text+0x3d4): undefined reference to `cpu_resume_mmu' arch/arm/kernel/setup.o: In function `setup_arch': setup.c:(.init.text+0x910): undefined reference to `init_uts_ns' kernel/nsproxy.o:(.data+0x4): undefined reference to `init_uts_ns' kernel/sched/core.o: In function `update_rq_clock': core.c:(.text+0x6d8): undefined reference to `paravirt_steal_rq_enabled' core.c:(.text+0x6dc): undefined reference to `pv_time_ops' kernel/sched/cputime.o: In function `account_process_tick': cputime.c:(.text+0x794): undefined reference to `paravirt_steal_enabled' cputime.c:(.text+0x7a0): undefined reference to `pv_time_ops' kernel/locking/lockdep.o: In function `save_trace': lockdep.c:(.text+0xfe8): undefined reference to `save_stack_trace' kernel/module.o: In function `load_module': module.c:(.text+0x1b54): undefined reference to `elf_check_arch' module.c:(.text+0x2024): undefined reference to `apply_relocate' kernel/debug/debug_core.o: In function `kgdb_unregister_io_module': debug_core.c:(.text+0x2e4): undefined reference to `kgdb_arch_exit' kernel/debug/debug_core.o: In function `kgdb_arch_set_breakpoint': debug_core.c:(.text+0x3bc): undefined reference to `arch_kgdb_ops' kernel/debug/debug_core.o: In function `dbg_remove_all_break': debug_core.c:(.text+0x6d0): undefined reference to `arch_kgdb_ops' ... However, I also see a link failure in some rare configurations with just your patch: arch/arm/lib/lib.a(io-acorn.o): In function `outsl': (.text+0x38): undefined reference to `printk' The problem being a file in a library object that is not referenced, but that references another symbol that is not defined (CONFIG_PRINTK=n). Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 10:10:51 AM CEST Stephen Rothwell wrote: > Hi Arnd, > > On Wed, 03 Aug 2016 20:52:48 +0200 Arnd Bergmannwrote: > > > > Most of the difference appears to be in branch trampolines (634 added, > > 559 removed, 14837 unchanged) as you suspect, but I also see a couple > > of symbols show up in vmlinux that were not there before: > > > > -A __crc_dma_noop_ops > > -D dma_noop_ops > > -R __clz_tab > > -r fdt_errtable > > -r __kcrctab_dma_noop_ops > > -r __kstrtab_dma_noop_ops > > -R __ksymtab_dma_noop_ops > > -t dma_noop_alloc > > -t dma_noop_free > > -t dma_noop_map_page > > -t dma_noop_mapping_error > > -t dma_noop_map_sg > > -t dma_noop_supported > > -T fdt_add_reservemap_entry > > -T fdt_begin_node > > -T fdt_create > > -T fdt_create_empty_tree > > -T fdt_end_node > > -T fdt_finish > > -T fdt_finish_reservemap > > -T fdt_property > > -T fdt_resize > > -T fdt_strerror > > -T find_cpio_data > > > > From my first look, it seems that all of lib/*.o is now getting linked > > into vmlinux, while we traditionally leave out everything from lib/ > > that is not referenced. > > You could try removing the --{,no-}whole-archive arguments to ld in > scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh. Last time I did > that, though, a whole lot of stuff failed to be linked in. (Especially > stuff only referenced by EXPORT_SYMBOL()s, bu that may have been fixed). I tried this diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index b5e40ed86e60..89bca1a25916 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -44,7 +44,7 @@ modpost_link() local objects if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then - objects="--whole-archive ${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN} --no-whole-archive" + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" else objects="${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group" fi but that did not seem to change anything, the extra symbols are still there. I have not tried to understand what that actually does, so maybe I misunderstood your suggestion. > > I also see a noticeable overhead in link time, the numbers are for > > a cache-hot rebuild after a successful allyesconfig build, using a > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > I was afraid of that, but it is offset by the time saved by not doing > the "ld -r"s along the way? It may also be that (for powerpc anyway) > the linker is doing a better job. At least on a big SMP system, it doesn't seem to make much difference, as the "ld -r" steps are easily parallized $ find build/ -name built-in.o | xargs rm ; time make -skj30 vmlinux real2m12.092s user3m52.932s sys 0m51.248s $ time make -skj30 vmlinux real2m12.162s user3m44.788s sys 0m47.788s I tried this twice with identical results: "user" time increases by eight seconds today when we have to rebuild all "built-in.o" files rather than just relinking vmlinux, but elapsed time is unchanged. After your patch that difference becomes smaller (three seconds in one run, could be within the noise), but we still have the extra two minutes for the total build time: $ find build/ -name built-in.o | xargs rm ; time make -skj30 vmlinux real4m20.717s user5m47.556s sys 0m54.128s $ time make -skj30 vmlinux real4m18.835s user5m44.552s sys 0m53.152s FWIW, here is a sample build output I get on an allyesconfig build, with timestamps added: $ time make W= -kj30 vmlinux make[1]: Entering directory '/git/arm-soc' make[2]: Entering directory '/git/arm-soc/build/tmp' 10:46:12 CHK include/config/kernel.release 10:46:13 GEN ./Makefile 10:46:13 CHK include/generated/uapi/linux/version.h Using /git/arm-soc as source for kernel 10:46:13 CHK include/generated/utsrelease.h 10:46:13 CHK include/generated/timeconst.h 10:46:13 CHK include/generated/bounds.h 10:46:13 CHK include/generated/asm-offsets.h 10:46:13 CALL/git/arm-soc/scripts/checksyscalls.sh 10:46:14 CHK include/generated/compile.h 10:46:18 CHK kernel/config_data.h 10:46:20 CC drivers/misc/lkdtm_rodata.o 10:46:20 OBJCOPY drivers/misc/lkdtm_rodata_objcopy.o 10:46:20 LD drivers/misc/lkdtm.o 10:46:20 LD drivers/misc/built-in.o 10:46:20 DTC drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb 10:46:20 DTB drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb.S 10:46:20 AS drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb.o 10:46:20 LD drivers/gpu/drm/tilcdc/built-in.o rm drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb.S drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb 10:46:33 LD drivers/gpu/drm/built-in.o 10:46:33 LD drivers/gpu/built-in.o 10:46:36 CHK include/generated/uapi/linux/version.h 10:46:36 LINKvmlinux 10:46:37 LD vmlinux.o 10:47:14 MODPOST vmlinux.o 10:47:16 GEN .version
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 10:10:51 AM CEST Stephen Rothwell wrote: > Hi Arnd, > > On Wed, 03 Aug 2016 20:52:48 +0200 Arnd Bergmann wrote: > > > > Most of the difference appears to be in branch trampolines (634 added, > > 559 removed, 14837 unchanged) as you suspect, but I also see a couple > > of symbols show up in vmlinux that were not there before: > > > > -A __crc_dma_noop_ops > > -D dma_noop_ops > > -R __clz_tab > > -r fdt_errtable > > -r __kcrctab_dma_noop_ops > > -r __kstrtab_dma_noop_ops > > -R __ksymtab_dma_noop_ops > > -t dma_noop_alloc > > -t dma_noop_free > > -t dma_noop_map_page > > -t dma_noop_mapping_error > > -t dma_noop_map_sg > > -t dma_noop_supported > > -T fdt_add_reservemap_entry > > -T fdt_begin_node > > -T fdt_create > > -T fdt_create_empty_tree > > -T fdt_end_node > > -T fdt_finish > > -T fdt_finish_reservemap > > -T fdt_property > > -T fdt_resize > > -T fdt_strerror > > -T find_cpio_data > > > > From my first look, it seems that all of lib/*.o is now getting linked > > into vmlinux, while we traditionally leave out everything from lib/ > > that is not referenced. > > You could try removing the --{,no-}whole-archive arguments to ld in > scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh. Last time I did > that, though, a whole lot of stuff failed to be linked in. (Especially > stuff only referenced by EXPORT_SYMBOL()s, bu that may have been fixed). I tried this diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index b5e40ed86e60..89bca1a25916 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -44,7 +44,7 @@ modpost_link() local objects if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then - objects="--whole-archive ${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN} --no-whole-archive" + objects="${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN}" else objects="${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group" fi but that did not seem to change anything, the extra symbols are still there. I have not tried to understand what that actually does, so maybe I misunderstood your suggestion. > > I also see a noticeable overhead in link time, the numbers are for > > a cache-hot rebuild after a successful allyesconfig build, using a > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > I was afraid of that, but it is offset by the time saved by not doing > the "ld -r"s along the way? It may also be that (for powerpc anyway) > the linker is doing a better job. At least on a big SMP system, it doesn't seem to make much difference, as the "ld -r" steps are easily parallized $ find build/ -name built-in.o | xargs rm ; time make -skj30 vmlinux real2m12.092s user3m52.932s sys 0m51.248s $ time make -skj30 vmlinux real2m12.162s user3m44.788s sys 0m47.788s I tried this twice with identical results: "user" time increases by eight seconds today when we have to rebuild all "built-in.o" files rather than just relinking vmlinux, but elapsed time is unchanged. After your patch that difference becomes smaller (three seconds in one run, could be within the noise), but we still have the extra two minutes for the total build time: $ find build/ -name built-in.o | xargs rm ; time make -skj30 vmlinux real4m20.717s user5m47.556s sys 0m54.128s $ time make -skj30 vmlinux real4m18.835s user5m44.552s sys 0m53.152s FWIW, here is a sample build output I get on an allyesconfig build, with timestamps added: $ time make W= -kj30 vmlinux make[1]: Entering directory '/git/arm-soc' make[2]: Entering directory '/git/arm-soc/build/tmp' 10:46:12 CHK include/config/kernel.release 10:46:13 GEN ./Makefile 10:46:13 CHK include/generated/uapi/linux/version.h Using /git/arm-soc as source for kernel 10:46:13 CHK include/generated/utsrelease.h 10:46:13 CHK include/generated/timeconst.h 10:46:13 CHK include/generated/bounds.h 10:46:13 CHK include/generated/asm-offsets.h 10:46:13 CALL/git/arm-soc/scripts/checksyscalls.sh 10:46:14 CHK include/generated/compile.h 10:46:18 CHK kernel/config_data.h 10:46:20 CC drivers/misc/lkdtm_rodata.o 10:46:20 OBJCOPY drivers/misc/lkdtm_rodata_objcopy.o 10:46:20 LD drivers/misc/lkdtm.o 10:46:20 LD drivers/misc/built-in.o 10:46:20 DTC drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb 10:46:20 DTB drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb.S 10:46:20 AS drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb.o 10:46:20 LD drivers/gpu/drm/tilcdc/built-in.o rm drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb.S drivers/gpu/drm/tilcdc/tilcdc_slave_compat.dtb 10:46:33 LD drivers/gpu/drm/built-in.o 10:46:33 LD drivers/gpu/built-in.o 10:46:36 CHK include/generated/uapi/linux/version.h 10:46:36 LINKvmlinux 10:46:37 LD vmlinux.o 10:47:14 MODPOST vmlinux.o 10:47:16 GEN .version 10:47:17 CHK
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Arnd, On Wed, 03 Aug 2016 20:52:48 +0200 Arnd Bergmannwrote: > > Most of the difference appears to be in branch trampolines (634 added, > 559 removed, 14837 unchanged) as you suspect, but I also see a couple > of symbols show up in vmlinux that were not there before: > > -A __crc_dma_noop_ops > -D dma_noop_ops > -R __clz_tab > -r fdt_errtable > -r __kcrctab_dma_noop_ops > -r __kstrtab_dma_noop_ops > -R __ksymtab_dma_noop_ops > -t dma_noop_alloc > -t dma_noop_free > -t dma_noop_map_page > -t dma_noop_mapping_error > -t dma_noop_map_sg > -t dma_noop_supported > -T fdt_add_reservemap_entry > -T fdt_begin_node > -T fdt_create > -T fdt_create_empty_tree > -T fdt_end_node > -T fdt_finish > -T fdt_finish_reservemap > -T fdt_property > -T fdt_resize > -T fdt_strerror > -T find_cpio_data > > From my first look, it seems that all of lib/*.o is now getting linked > into vmlinux, while we traditionally leave out everything from lib/ > that is not referenced. You could try removing the --{,no-}whole-archive arguments to ld in scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh. Last time I did that, though, a whole lot of stuff failed to be linked in. (Especially stuff only referenced by EXPORT_SYMBOL()s, bu that may have been fixed). > I also see a noticeable overhead in link time, the numbers are for > a cache-hot rebuild after a successful allyesconfig build, using a > 24-way Opteron@2.5Ghz, just relinking vmlinux: I was afraid of that, but it is offset by the time saved by not doing the "ld -r"s along the way? It may also be that (for powerpc anyway) the linker is doing a better job. -- Cheers, Stephen Rothwell
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Arnd, On Wed, 03 Aug 2016 20:52:48 +0200 Arnd Bergmann wrote: > > Most of the difference appears to be in branch trampolines (634 added, > 559 removed, 14837 unchanged) as you suspect, but I also see a couple > of symbols show up in vmlinux that were not there before: > > -A __crc_dma_noop_ops > -D dma_noop_ops > -R __clz_tab > -r fdt_errtable > -r __kcrctab_dma_noop_ops > -r __kstrtab_dma_noop_ops > -R __ksymtab_dma_noop_ops > -t dma_noop_alloc > -t dma_noop_free > -t dma_noop_map_page > -t dma_noop_mapping_error > -t dma_noop_map_sg > -t dma_noop_supported > -T fdt_add_reservemap_entry > -T fdt_begin_node > -T fdt_create > -T fdt_create_empty_tree > -T fdt_end_node > -T fdt_finish > -T fdt_finish_reservemap > -T fdt_property > -T fdt_resize > -T fdt_strerror > -T find_cpio_data > > From my first look, it seems that all of lib/*.o is now getting linked > into vmlinux, while we traditionally leave out everything from lib/ > that is not referenced. You could try removing the --{,no-}whole-archive arguments to ld in scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh. Last time I did that, though, a whole lot of stuff failed to be linked in. (Especially stuff only referenced by EXPORT_SYMBOL()s, bu that may have been fixed). > I also see a noticeable overhead in link time, the numbers are for > a cache-hot rebuild after a successful allyesconfig build, using a > 24-way Opteron@2.5Ghz, just relinking vmlinux: I was afraid of that, but it is offset by the time saved by not doing the "ld -r"s along the way? It may also be that (for powerpc anyway) the linker is doing a better job. -- Cheers, Stephen Rothwell
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Arnd, On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > From my first look, it seems that all of lib/*.o is now getting linked > into vmlinux, while we traditionally leave out everything from lib/ > that is not referenced. > > I also see a noticeable overhead in link time, the numbers are for > a cache-hot rebuild after a successful allyesconfig build, using a > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > $ time make skj30 vmlinux # before > real 2m8.092s > user 3m41.008s > sys 0m48.172s > > $ time make skj30 vmlinux # after > real 4m10.189s > user 5m43.804s > sys 0m52.988s Is it better when using rcT instead of rcsT? Segher
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Arnd, On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > From my first look, it seems that all of lib/*.o is now getting linked > into vmlinux, while we traditionally leave out everything from lib/ > that is not referenced. > > I also see a noticeable overhead in link time, the numbers are for > a cache-hot rebuild after a successful allyesconfig build, using a > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > $ time make skj30 vmlinux # before > real 2m8.092s > user 3m41.008s > sys 0m48.172s > > $ time make skj30 vmlinux # after > real 4m10.189s > user 5m43.804s > sys 0m52.988s Is it better when using rcT instead of rcsT? Segher
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 2:44:29 PM CEST Segher Boessenkool wrote: > Hi Arnd, > > On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > > From my first look, it seems that all of lib/*.o is now getting linked > > into vmlinux, while we traditionally leave out everything from lib/ > > that is not referenced. > > > > I also see a noticeable overhead in link time, the numbers are for > > a cache-hot rebuild after a successful allyesconfig build, using a > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > > > $ time make skj30 vmlinux # before > > real2m8.092s > > user3m41.008s > > sys 0m48.172s > > > > $ time make skj30 vmlinux # after > > real4m10.189s > > user5m43.804s > > sys 0m52.988s > > Is it better when using rcT instead of rcsT? It seems to be noticeably better for the clean rebuild case, though not as good as the original: real3m34.015s user5m7.104s sys 0m49.172s I've also tried now with my own patch applied as well (linking each drivers/*/built-in.o into vmlinux rather than having them linked into drivers/built-in.o first), but that makes no difference. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 2:44:29 PM CEST Segher Boessenkool wrote: > Hi Arnd, > > On Wed, Aug 03, 2016 at 08:52:48PM +0200, Arnd Bergmann wrote: > > From my first look, it seems that all of lib/*.o is now getting linked > > into vmlinux, while we traditionally leave out everything from lib/ > > that is not referenced. > > > > I also see a noticeable overhead in link time, the numbers are for > > a cache-hot rebuild after a successful allyesconfig build, using a > > 24-way Opteron@2.5Ghz, just relinking vmlinux: > > > > $ time make skj30 vmlinux # before > > real2m8.092s > > user3m41.008s > > sys 0m48.172s > > > > $ time make skj30 vmlinux # after > > real4m10.189s > > user5m43.804s > > sys 0m52.988s > > Is it better when using rcT instead of rcsT? It seems to be noticeably better for the clean rebuild case, though not as good as the original: real3m34.015s user5m7.104s sys 0m49.172s I've also tried now with my own patch applied as well (linking each drivers/*/built-in.o into vmlinux rather than having them linked into drivers/built-in.o first), but that makes no difference. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 1:37:29 AM CEST Nicholas Piggin wrote: > > I've attached what I'm using, which builds and runs for me without > any work. Your arch obviously has to select the option to use it. > > text data bss dec hex filename > 11196784 1185024 1923820 14305628 da495c vmlinuxppc64.before > 11187536 1181848 1923176 14292560 da1650 vmlinuxppc64.after > > ~9K text saving, ~3K data saving. I assume this comes from fewer > branch trampolines and toc entries, but haven't verified exactly. The patch seems to work great, but for me it's getting bigger (compared to my older patch, mainline allyesconfig doesn't build): textdata bss dec hex filename 512998684259955923362148117261575 6fd4507 vmlinuxarm.before 513025454259501523361884117259444 6fd3cb4 vmlinuxarm.after Most of the difference appears to be in branch trampolines (634 added, 559 removed, 14837 unchanged) as you suspect, but I also see a couple of symbols show up in vmlinux that were not there before: -A __crc_dma_noop_ops -D dma_noop_ops -R __clz_tab -r fdt_errtable -r __kcrctab_dma_noop_ops -r __kstrtab_dma_noop_ops -R __ksymtab_dma_noop_ops -t dma_noop_alloc -t dma_noop_free -t dma_noop_map_page -t dma_noop_mapping_error -t dma_noop_map_sg -t dma_noop_supported -T fdt_add_reservemap_entry -T fdt_begin_node -T fdt_create -T fdt_create_empty_tree -T fdt_end_node -T fdt_finish -T fdt_finish_reservemap -T fdt_property -T fdt_resize -T fdt_strerror -T find_cpio_data >From my first look, it seems that all of lib/*.o is now getting linked into vmlinux, while we traditionally leave out everything from lib/ that is not referenced. I also see a noticeable overhead in link time, the numbers are for a cache-hot rebuild after a successful allyesconfig build, using a 24-way Opteron@2.5Ghz, just relinking vmlinux: $ time make skj30 vmlinux # before real2m8.092s user3m41.008s sys 0m48.172s $ time make skj30 vmlinux # after real4m10.189s user5m43.804s sys 0m52.988s That is clearly a very sharp difference. Fortunately for the defconfig build, the times are much lower, and I see no real difference other than the noise between subsequent runs: $ time make skj30 vmlinux # before real0m5.415s user0m19.716s sys 0m9.356s $ time make skj30 vmlinux # before real0m9.536s user0m21.320s sys 0m9.224s $ time make skj30 vmlinux # after real0m5.539s user0m20.360s sys 0m9.224s $ time make skj30 vmlinux # after real0m9.138s user0m21.932s sys 0m8.988s $ time make skj30 vmlinux # after real0m5.659s user0m20.332s sys 0m9.620s Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Thursday, August 4, 2016 1:37:29 AM CEST Nicholas Piggin wrote: > > I've attached what I'm using, which builds and runs for me without > any work. Your arch obviously has to select the option to use it. > > text data bss dec hex filename > 11196784 1185024 1923820 14305628 da495c vmlinuxppc64.before > 11187536 1181848 1923176 14292560 da1650 vmlinuxppc64.after > > ~9K text saving, ~3K data saving. I assume this comes from fewer > branch trampolines and toc entries, but haven't verified exactly. The patch seems to work great, but for me it's getting bigger (compared to my older patch, mainline allyesconfig doesn't build): textdata bss dec hex filename 512998684259955923362148117261575 6fd4507 vmlinuxarm.before 513025454259501523361884117259444 6fd3cb4 vmlinuxarm.after Most of the difference appears to be in branch trampolines (634 added, 559 removed, 14837 unchanged) as you suspect, but I also see a couple of symbols show up in vmlinux that were not there before: -A __crc_dma_noop_ops -D dma_noop_ops -R __clz_tab -r fdt_errtable -r __kcrctab_dma_noop_ops -r __kstrtab_dma_noop_ops -R __ksymtab_dma_noop_ops -t dma_noop_alloc -t dma_noop_free -t dma_noop_map_page -t dma_noop_mapping_error -t dma_noop_map_sg -t dma_noop_supported -T fdt_add_reservemap_entry -T fdt_begin_node -T fdt_create -T fdt_create_empty_tree -T fdt_end_node -T fdt_finish -T fdt_finish_reservemap -T fdt_property -T fdt_resize -T fdt_strerror -T find_cpio_data >From my first look, it seems that all of lib/*.o is now getting linked into vmlinux, while we traditionally leave out everything from lib/ that is not referenced. I also see a noticeable overhead in link time, the numbers are for a cache-hot rebuild after a successful allyesconfig build, using a 24-way Opteron@2.5Ghz, just relinking vmlinux: $ time make skj30 vmlinux # before real2m8.092s user3m41.008s sys 0m48.172s $ time make skj30 vmlinux # after real4m10.189s user5m43.804s sys 0m52.988s That is clearly a very sharp difference. Fortunately for the defconfig build, the times are much lower, and I see no real difference other than the noise between subsequent runs: $ time make skj30 vmlinux # before real0m5.415s user0m19.716s sys 0m9.356s $ time make skj30 vmlinux # before real0m9.536s user0m21.320s sys 0m9.224s $ time make skj30 vmlinux # after real0m5.539s user0m20.360s sys 0m9.224s $ time make skj30 vmlinux # after real0m9.138s user0m21.932s sys 0m8.988s $ time make skj30 vmlinux # after real0m5.659s user0m20.332s sys 0m9.620s Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wed, 03 Aug 2016 14:29:13 +0200 Arnd Bergmannwrote: > On Wednesday, August 3, 2016 10:19:11 PM CEST Stephen Rothwell wrote: > > Hi Arnd, > > > > On Wed, 03 Aug 2016 09:52:23 +0200 Arnd Bergmann wrote: > > > > > > Using a different way to link the kernel would also help us with > > > the remaining allyesconfig problem on ARM, as the problem is only in > > > 'ld -r' not producing trampolines for symbols that later cannot get > > > them any more. It would probably also help building with ld.gold, > > > which is currently not working. > > > > > > What is your suggested alternative? > > > > I have a patch that make the built-in.o files into thin archives (same > > as archives, but the actual objects are replaced with the name of the > > original object file). That way the final link has all the original > > objects. I haven't checked to see what the overheads of doing it this > > way is. > > > > Nick Piggin has just today taken my old patch (it was last rebased to > > v4.4-rc1) and tried it on a recent kernel and it still seems to mostly > > work. It probably needs some tidying up, but you are welcome to test > > it if you want to. > > Sure, I'll certainly give it a try on ARM when you send me a copy. I've attached what I'm using, which builds and runs for me without any work. Your arch obviously has to select the option to use it. text data bss dec hex filename 11196784 1185024 1923820 14305628 da495c vmlinuxppc64.before 11187536 1181848 1923176 14292560 da1650 vmlinuxppc64.after ~9K text saving, ~3K data saving. I assume this comes from fewer branch trampolines and toc entries, but haven't verified exactly. commit 8bc3ca4798c215e9a9107b6d44408f0af259f84f Author: Stephen Rothwell Date: Tue Oct 30 12:14:18 2012 +1100 kbuild: allow architectures to use thin archives instead of ld -r Alan Modra has been trying to convince the kernel developers that ld -r is "evil" for many years. This is an alternative and means that the linker has much more information available to it when it links the kernel. Signed-off-by: Stephen Rothwell diff --git a/arch/Kconfig b/arch/Kconfig index d794384..1330bf4 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -424,6 +424,12 @@ config CC_STACKPROTECTOR_STRONG endchoice +config THIN_ARCHIVES + bool + help + Select this if the architecture wants to use thin archives + instead of ld -r to create the built-in.o files. + config HAVE_CONTEXT_TRACKING bool help diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 0d1ca5b..bbf60b3 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -358,10 +358,15 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ; # Rule to compile a set of .o files into one .o file # ifdef builtin-target +ifdef CONFIG_THIN_ARCHIVES + cmd_make_builtin = rm -f $@; $(AR) rcsT$(KBUILD_ARFLAGS) +else + cmd_make_builtin = $(LD) $(ld_flags) -r -o +endif quiet_cmd_link_o_target = LD $@ # If the list of objects to link is empty, just create an empty built-in.o cmd_link_o_target = $(if $(strip $(obj-y)),\ - $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \ + $(cmd_make_builtin) $@ $(filter $(obj-y), $^) \ $(cmd_secanalysis),\ rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@) diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index f0f6d9d..ef4658f 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -41,8 +41,14 @@ info() # ${1} output file modpost_link() { - ${LD} ${LDFLAGS} -r -o ${1} ${KBUILD_VMLINUX_INIT} \ - --start-group ${KBUILD_VMLINUX_MAIN} --end-group + local objects + + if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then + objects="--whole-archive ${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN} --no-whole-archive" + else + objects="${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group" + fi + ${LD} ${LDFLAGS} -r -o ${1} ${objects} } # Link of vmlinux @@ -51,11 +57,16 @@ modpost_link() vmlinux_link() { local lds="${objtree}/${KBUILD_LDS}" + local objects if [ "${SRCARCH}" != "um" ]; then + if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then + objects="--whole-archive ${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN} --no-whole-archive" + else + objects="${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group" + fi ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} \ - -T ${lds} ${KBUILD_VMLINUX_INIT} \ - --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1} + -T
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wed, 03 Aug 2016 14:29:13 +0200 Arnd Bergmann wrote: > On Wednesday, August 3, 2016 10:19:11 PM CEST Stephen Rothwell wrote: > > Hi Arnd, > > > > On Wed, 03 Aug 2016 09:52:23 +0200 Arnd Bergmann wrote: > > > > > > Using a different way to link the kernel would also help us with > > > the remaining allyesconfig problem on ARM, as the problem is only in > > > 'ld -r' not producing trampolines for symbols that later cannot get > > > them any more. It would probably also help building with ld.gold, > > > which is currently not working. > > > > > > What is your suggested alternative? > > > > I have a patch that make the built-in.o files into thin archives (same > > as archives, but the actual objects are replaced with the name of the > > original object file). That way the final link has all the original > > objects. I haven't checked to see what the overheads of doing it this > > way is. > > > > Nick Piggin has just today taken my old patch (it was last rebased to > > v4.4-rc1) and tried it on a recent kernel and it still seems to mostly > > work. It probably needs some tidying up, but you are welcome to test > > it if you want to. > > Sure, I'll certainly give it a try on ARM when you send me a copy. I've attached what I'm using, which builds and runs for me without any work. Your arch obviously has to select the option to use it. text data bss dec hex filename 11196784 1185024 1923820 14305628 da495c vmlinuxppc64.before 11187536 1181848 1923176 14292560 da1650 vmlinuxppc64.after ~9K text saving, ~3K data saving. I assume this comes from fewer branch trampolines and toc entries, but haven't verified exactly. commit 8bc3ca4798c215e9a9107b6d44408f0af259f84f Author: Stephen Rothwell Date: Tue Oct 30 12:14:18 2012 +1100 kbuild: allow architectures to use thin archives instead of ld -r Alan Modra has been trying to convince the kernel developers that ld -r is "evil" for many years. This is an alternative and means that the linker has much more information available to it when it links the kernel. Signed-off-by: Stephen Rothwell diff --git a/arch/Kconfig b/arch/Kconfig index d794384..1330bf4 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -424,6 +424,12 @@ config CC_STACKPROTECTOR_STRONG endchoice +config THIN_ARCHIVES + bool + help + Select this if the architecture wants to use thin archives + instead of ld -r to create the built-in.o files. + config HAVE_CONTEXT_TRACKING bool help diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 0d1ca5b..bbf60b3 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -358,10 +358,15 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ; # Rule to compile a set of .o files into one .o file # ifdef builtin-target +ifdef CONFIG_THIN_ARCHIVES + cmd_make_builtin = rm -f $@; $(AR) rcsT$(KBUILD_ARFLAGS) +else + cmd_make_builtin = $(LD) $(ld_flags) -r -o +endif quiet_cmd_link_o_target = LD $@ # If the list of objects to link is empty, just create an empty built-in.o cmd_link_o_target = $(if $(strip $(obj-y)),\ - $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \ + $(cmd_make_builtin) $@ $(filter $(obj-y), $^) \ $(cmd_secanalysis),\ rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@) diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index f0f6d9d..ef4658f 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -41,8 +41,14 @@ info() # ${1} output file modpost_link() { - ${LD} ${LDFLAGS} -r -o ${1} ${KBUILD_VMLINUX_INIT} \ - --start-group ${KBUILD_VMLINUX_MAIN} --end-group + local objects + + if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then + objects="--whole-archive ${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN} --no-whole-archive" + else + objects="${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group" + fi + ${LD} ${LDFLAGS} -r -o ${1} ${objects} } # Link of vmlinux @@ -51,11 +57,16 @@ modpost_link() vmlinux_link() { local lds="${objtree}/${KBUILD_LDS}" + local objects if [ "${SRCARCH}" != "um" ]; then + if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then + objects="--whole-archive ${KBUILD_VMLINUX_INIT} ${KBUILD_VMLINUX_MAIN} --no-whole-archive" + else + objects="${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group" + fi ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} \ - -T ${lds} ${KBUILD_VMLINUX_INIT} \ - --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1} + -T ${lds} ${objects} ${1} else ${CC} ${CFLAGS_vmlinux} -o
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 10:19:11 PM CEST Stephen Rothwell wrote: > Hi Arnd, > > On Wed, 03 Aug 2016 09:52:23 +0200 Arnd Bergmannwrote: > > > > Using a different way to link the kernel would also help us with > > the remaining allyesconfig problem on ARM, as the problem is only in > > 'ld -r' not producing trampolines for symbols that later cannot get > > them any more. It would probably also help building with ld.gold, > > which is currently not working. > > > > What is your suggested alternative? > > I have a patch that make the built-in.o files into thin archives (same > as archives, but the actual objects are replaced with the name of the > original object file). That way the final link has all the original > objects. I haven't checked to see what the overheads of doing it this > way is. > > Nick Piggin has just today taken my old patch (it was last rebased to > v4.4-rc1) and tried it on a recent kernel and it still seems to mostly > work. It probably needs some tidying up, but you are welcome to test > it if you want to. Sure, I'll certainly give it a try on ARM when you send me a copy. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 10:19:11 PM CEST Stephen Rothwell wrote: > Hi Arnd, > > On Wed, 03 Aug 2016 09:52:23 +0200 Arnd Bergmann wrote: > > > > Using a different way to link the kernel would also help us with > > the remaining allyesconfig problem on ARM, as the problem is only in > > 'ld -r' not producing trampolines for symbols that later cannot get > > them any more. It would probably also help building with ld.gold, > > which is currently not working. > > > > What is your suggested alternative? > > I have a patch that make the built-in.o files into thin archives (same > as archives, but the actual objects are replaced with the name of the > original object file). That way the final link has all the original > objects. I haven't checked to see what the overheads of doing it this > way is. > > Nick Piggin has just today taken my old patch (it was last rebased to > v4.4-rc1) and tried it on a recent kernel and it still seems to mostly > work. It probably needs some tidying up, but you are welcome to test > it if you want to. Sure, I'll certainly give it a try on ARM when you send me a copy. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Arnd, On Wed, 03 Aug 2016 09:52:23 +0200 Arnd Bergmannwrote: > > Using a different way to link the kernel would also help us with > the remaining allyesconfig problem on ARM, as the problem is only in > 'ld -r' not producing trampolines for symbols that later cannot get > them any more. It would probably also help building with ld.gold, > which is currently not working. > > What is your suggested alternative? I have a patch that make the built-in.o files into thin archives (same as archives, but the actual objects are replaced with the name of the original object file). That way the final link has all the original objects. I haven't checked to see what the overheads of doing it this way is. Nick Piggin has just today taken my old patch (it was last rebased to v4.4-rc1) and tried it on a recent kernel and it still seems to mostly work. It probably needs some tidying up, but you are welcome to test it if you want to. -- Cheers, Stephen Rothwell
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Arnd, On Wed, 03 Aug 2016 09:52:23 +0200 Arnd Bergmann wrote: > > Using a different way to link the kernel would also help us with > the remaining allyesconfig problem on ARM, as the problem is only in > 'ld -r' not producing trampolines for symbols that later cannot get > them any more. It would probably also help building with ld.gold, > which is currently not working. > > What is your suggested alternative? I have a patch that make the built-in.o files into thin archives (same as archives, but the actual objects are replaced with the name of the original object file). That way the final link has all the original objects. I haven't checked to see what the overheads of doing it this way is. Nick Piggin has just today taken my old patch (it was last rebased to v4.4-rc1) and tried it on a recent kernel and it still seems to mostly work. It probably needs some tidying up, but you are welcome to test it if you want to. -- Cheers, Stephen Rothwell
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 10:23:24 AM CEST Stephen Rothwell wrote: > Hi Luis, > > On Wed, 3 Aug 2016 00:02:43 +0200 "Luis R. Rodriguez"> wrote: > > > > Thanks for the confirmation. For how long is it known this is broken? > > Does anyone care and fix these ? Or is this best effort? > > This has been broken for many years > > I have a couple of times almost fixed it, but it requires that we > change from using "ld -r" to build the built-in.o objects and some > changes to the powerpc head.S code ... I will give it another shot now > that the merge window is almost over (and linux-next goes into its > quieter time). Using a different way to link the kernel would also help us with the remaining allyesconfig problem on ARM, as the problem is only in 'ld -r' not producing trampolines for symbols that later cannot get them any more. It would probably also help building with ld.gold, which is currently not working. What is your suggested alternative? Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 10:23:24 AM CEST Stephen Rothwell wrote: > Hi Luis, > > On Wed, 3 Aug 2016 00:02:43 +0200 "Luis R. Rodriguez" > wrote: > > > > Thanks for the confirmation. For how long is it known this is broken? > > Does anyone care and fix these ? Or is this best effort? > > This has been broken for many years > > I have a couple of times almost fixed it, but it requires that we > change from using "ld -r" to build the built-in.o objects and some > changes to the powerpc head.S code ... I will give it another shot now > that the merge window is almost over (and linux-next goes into its > quieter time). Using a different way to link the kernel would also help us with the remaining allyesconfig problem on ARM, as the problem is only in 'ld -r' not producing trampolines for symbols that later cannot get them any more. It would probably also help building with ld.gold, which is currently not working. What is your suggested alternative? Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
"Luis R. Rodriguez"writes: > Are linux-next builds being tested for powerpc with allyesconfig and > allmodconfig ? Yes, every single version: http://kisskb.ellerman.id.au/kisskb/target/2659/ > I have some changes I'm making and while debugging my > build issues I decided to give a clean build a shot and see linux-next > next-20160729 up to next-20160729 all have build failures without my > changes. I get: > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > MODPOST vmlinux.o > GEN .version > CHK include/generated/compile.h > UPD include/generated/compile.h > CC init/version.o > LD init/built-in.o > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > drivers/built-in.o: In function `.ipw2100_up': > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: > R_PPC64_REL24 (stub) against symbol `.round_jiffies_relative' defined > in .text section in kernel/built-in.o And yes this is a known problem, there have been attempts to fix it, but none that quite got working. In fact it's our bug #1 :) https://github.com/linuxppc/linux/issues/1 Please use allmodconfig, which should build in general. Or one of our other defconfigs, eg. ppc64/ppc64le defconfig. cheers
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
"Luis R. Rodriguez" writes: > Are linux-next builds being tested for powerpc with allyesconfig and > allmodconfig ? Yes, every single version: http://kisskb.ellerman.id.au/kisskb/target/2659/ > I have some changes I'm making and while debugging my > build issues I decided to give a clean build a shot and see linux-next > next-20160729 up to next-20160729 all have build failures without my > changes. I get: > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > MODPOST vmlinux.o > GEN .version > CHK include/generated/compile.h > UPD include/generated/compile.h > CC init/version.o > LD init/built-in.o > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > drivers/built-in.o: In function `.ipw2100_up': > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: > R_PPC64_REL24 (stub) against symbol `.round_jiffies_relative' defined > in .text section in kernel/built-in.o And yes this is a known problem, there have been attempts to fix it, but none that quite got working. In fact it's our bug #1 :) https://github.com/linuxppc/linux/issues/1 Please use allmodconfig, which should build in general. Or one of our other defconfigs, eg. ppc64/ppc64le defconfig. cheers
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Luis, On Wed, 3 Aug 2016 00:02:43 +0200 "Luis R. Rodriguez"wrote: > > Thanks for the confirmation. For how long is it known this is broken? > Does anyone care and fix these ? Or is this best effort? This has been broken for many years :-( I have a couple of times almost fixed it, but it requires that we change from using "ld -r" to build the built-in.o objects and some changes to the powerpc head.S code ... I will give it another shot now that the merge window is almost over (and linux-next goes into its quieter time). -- Cheers, Stephen Rothwell
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Hi Luis, On Wed, 3 Aug 2016 00:02:43 +0200 "Luis R. Rodriguez" wrote: > > Thanks for the confirmation. For how long is it known this is broken? > Does anyone care and fix these ? Or is this best effort? This has been broken for many years :-( I have a couple of times almost fixed it, but it requires that we change from using "ld -r" to build the built-in.o objects and some changes to the powerpc head.S code ... I will give it another shot now that the merge window is almost over (and linux-next goes into its quieter time). -- Cheers, Stephen Rothwell
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 12:02:43 AM CEST Luis R. Rodriguez wrote: > On Tue, Aug 02, 2016 at 02:58:39PM -0700, Guenter Roeck wrote: > > On Tue, Aug 02, 2016 at 01:07:09PM -0700, Luis R. Rodriguez wrote: > > > Are linux-next builds being tested for powerpc with allyesconfig and > > > allmodconfig ? I have some changes I'm making and while debugging my > > > build issues I decided to give a clean build a shot and see linux-next > > > next-20160729 up to next-20160729 all have build failures without my > > > changes. I get: > > > > > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > > drivers/built-in.o: .opd is not a regular array of opd entries > > > MODPOST vmlinux.o > > > GEN .version > > > CHK include/generated/compile.h > > > UPD include/generated/compile.h > > > CC init/version.o > > > LD init/built-in.o > > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > > drivers/built-in.o: .opd is not a regular array of opd entries > > > drivers/built-in.o: In function `.ipw2100_up': > > > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: > > > > "relocation truncated to fit" errors are typical for ppc:allyesconfig. > > Thanks for the confirmation. For how long is it known this is broken? > Does anyone care and fix these ? Or is this best effort? We used to have the same thing on ARM, but it's (mostly) fixed now. In case of ARM, the solution was to ensure that all sections that have long jumps or targets of long jumps are marked as executable in the ELF headers, so the linker can insert trampolines. The one remaining problem at the moment is related to recursive linking of the drivers/ directory, which has .text section that is larger than 32MB by itself. There is a patch to solve this by linking each drivers/*/built-in.o object directly into vmlinux, but that is a rather drastic change. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Wednesday, August 3, 2016 12:02:43 AM CEST Luis R. Rodriguez wrote: > On Tue, Aug 02, 2016 at 02:58:39PM -0700, Guenter Roeck wrote: > > On Tue, Aug 02, 2016 at 01:07:09PM -0700, Luis R. Rodriguez wrote: > > > Are linux-next builds being tested for powerpc with allyesconfig and > > > allmodconfig ? I have some changes I'm making and while debugging my > > > build issues I decided to give a clean build a shot and see linux-next > > > next-20160729 up to next-20160729 all have build failures without my > > > changes. I get: > > > > > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > > drivers/built-in.o: .opd is not a regular array of opd entries > > > MODPOST vmlinux.o > > > GEN .version > > > CHK include/generated/compile.h > > > UPD include/generated/compile.h > > > CC init/version.o > > > LD init/built-in.o > > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > > drivers/built-in.o: .opd is not a regular array of opd entries > > > drivers/built-in.o: In function `.ipw2100_up': > > > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: > > > > "relocation truncated to fit" errors are typical for ppc:allyesconfig. > > Thanks for the confirmation. For how long is it known this is broken? > Does anyone care and fix these ? Or is this best effort? We used to have the same thing on ARM, but it's (mostly) fixed now. In case of ARM, the solution was to ensure that all sections that have long jumps or targets of long jumps are marked as executable in the ELF headers, so the linker can insert trampolines. The one remaining problem at the moment is related to recursive linking of the drivers/ directory, which has .text section that is larger than 32MB by itself. There is a patch to solve this by linking each drivers/*/built-in.o object directly into vmlinux, but that is a rather drastic change. Arnd
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Tue, Aug 02, 2016 at 02:58:39PM -0700, Guenter Roeck wrote: > On Tue, Aug 02, 2016 at 01:07:09PM -0700, Luis R. Rodriguez wrote: > > Are linux-next builds being tested for powerpc with allyesconfig and > > allmodconfig ? I have some changes I'm making and while debugging my > > build issues I decided to give a clean build a shot and see linux-next > > next-20160729 up to next-20160729 all have build failures without my > > changes. I get: > > > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > drivers/built-in.o: .opd is not a regular array of opd entries > > MODPOST vmlinux.o > > GEN .version > > CHK include/generated/compile.h > > UPD include/generated/compile.h > > CC init/version.o > > LD init/built-in.o > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > drivers/built-in.o: .opd is not a regular array of opd entries > > drivers/built-in.o: In function `.ipw2100_up': > > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: > > "relocation truncated to fit" errors are typical for ppc:allyesconfig. Thanks for the confirmation. For how long is it known this is broken? Does anyone care and fix these ? Or is this best effort? > allmodconfig should work, though. OK thanks. Luis
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Tue, Aug 02, 2016 at 02:58:39PM -0700, Guenter Roeck wrote: > On Tue, Aug 02, 2016 at 01:07:09PM -0700, Luis R. Rodriguez wrote: > > Are linux-next builds being tested for powerpc with allyesconfig and > > allmodconfig ? I have some changes I'm making and while debugging my > > build issues I decided to give a clean build a shot and see linux-next > > next-20160729 up to next-20160729 all have build failures without my > > changes. I get: > > > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > drivers/built-in.o: .opd is not a regular array of opd entries > > MODPOST vmlinux.o > > GEN .version > > CHK include/generated/compile.h > > UPD include/generated/compile.h > > CC init/version.o > > LD init/built-in.o > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > > drivers/built-in.o: .opd is not a regular array of opd entries > > drivers/built-in.o: In function `.ipw2100_up': > > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: > > "relocation truncated to fit" errors are typical for ppc:allyesconfig. Thanks for the confirmation. For how long is it known this is broken? Does anyone care and fix these ? Or is this best effort? > allmodconfig should work, though. OK thanks. Luis
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Tue, Aug 02, 2016 at 01:07:09PM -0700, Luis R. Rodriguez wrote: > Are linux-next builds being tested for powerpc with allyesconfig and > allmodconfig ? I have some changes I'm making and while debugging my > build issues I decided to give a clean build a shot and see linux-next > next-20160729 up to next-20160729 all have build failures without my > changes. I get: > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > MODPOST vmlinux.o > GEN .version > CHK include/generated/compile.h > UPD include/generated/compile.h > CC init/version.o > LD init/built-in.o > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > drivers/built-in.o: In function `.ipw2100_up': > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: "relocation truncated to fit" errors are typical for ppc:allyesconfig. allmodconfig should work, though. Guenter
Re: powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
On Tue, Aug 02, 2016 at 01:07:09PM -0700, Luis R. Rodriguez wrote: > Are linux-next builds being tested for powerpc with allyesconfig and > allmodconfig ? I have some changes I'm making and while debugging my > build issues I decided to give a clean build a shot and see linux-next > next-20160729 up to next-20160729 all have build failures without my > changes. I get: > > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > MODPOST vmlinux.o > GEN .version > CHK include/generated/compile.h > UPD include/generated/compile.h > CC init/version.o > LD init/built-in.o > /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: > drivers/built-in.o: .opd is not a regular array of opd entries > drivers/built-in.o: In function `.ipw2100_up': > ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: "relocation truncated to fit" errors are typical for ppc:allyesconfig. allmodconfig should work, though. Guenter
powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Are linux-next builds being tested for powerpc with allyesconfig and allmodconfig ? I have some changes I'm making and while debugging my build issues I decided to give a clean build a shot and see linux-next next-20160729 up to next-20160729 all have build failures without my changes. I get: /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries MODPOST vmlinux.o GEN .version CHK include/generated/compile.h UPD include/generated/compile.h CC init/version.o LD init/built-in.o /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries drivers/built-in.o: In function `.ipw2100_up': ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.round_jiffies_relative' defined in .text section in kernel/built-in.o drivers/built-in.o: In function `.ipw2100_reset_adapter': ipw2100.c:(.text+0x1ffa500): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `._raw_spin_lock_irqsave' defined in .spinlock.text section in kernel/built-in.o drivers/built-in.o: In function `.ipw2100_irq_tasklet': ipw2100.c:(.text+0x1ffa7cc): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `._raw_spin_lock_irqsave' defined in .spinlock.text section in kernel/built-in.o ipw2100.c:(.text+0x1ffb6c8): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb6d8): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb740): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb750): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb7ec): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.debug_dma_unmap_page' defined in .text section in lib/built-in.o ipw2100.c:(.text+0x1ffb88c): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.__dev_kfree_skb_any' defined in .text section in net/built-in.o ipw2100.c:(.text+0x1ffb8b8): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb8f4): additional relocation overflows omitted from the output scripts/link-vmlinux.sh: line 52: 14580 Segmentation fault (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1} make: *** [Makefile:952: vmlinux] Error 139 Luis
powerpc allyesconfig / allmodconfig linux-next next-20160729 - next-20160729 build failures
Are linux-next builds being tested for powerpc with allyesconfig and allmodconfig ? I have some changes I'm making and while debugging my build issues I decided to give a clean build a shot and see linux-next next-20160729 up to next-20160729 all have build failures without my changes. I get: /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries MODPOST vmlinux.o GEN .version CHK include/generated/compile.h UPD include/generated/compile.h CC init/version.o LD init/built-in.o /opt/gcc-4.9.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries drivers/built-in.o: In function `.ipw2100_up': ipw2100.c:(.text+0x1ff9c90): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.round_jiffies_relative' defined in .text section in kernel/built-in.o drivers/built-in.o: In function `.ipw2100_reset_adapter': ipw2100.c:(.text+0x1ffa500): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `._raw_spin_lock_irqsave' defined in .spinlock.text section in kernel/built-in.o drivers/built-in.o: In function `.ipw2100_irq_tasklet': ipw2100.c:(.text+0x1ffa7cc): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `._raw_spin_lock_irqsave' defined in .spinlock.text section in kernel/built-in.o ipw2100.c:(.text+0x1ffb6c8): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb6d8): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb740): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb750): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb7ec): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.debug_dma_unmap_page' defined in .text section in lib/built-in.o ipw2100.c:(.text+0x1ffb88c): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.__dev_kfree_skb_any' defined in .text section in net/built-in.o ipw2100.c:(.text+0x1ffb8b8): relocation truncated to fit: R_PPC64_REL24 (stub) against symbol `.printk' defined in .text.unlikely section in kernel/built-in.o ipw2100.c:(.text+0x1ffb8f4): additional relocation overflows omitted from the output scripts/link-vmlinux.sh: line 52: 14580 Segmentation fault (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1} make: *** [Makefile:952: vmlinux] Error 139 Luis