I agree, let's do it.
Klemens Nanni <k...@openbsd.org> wrote:
> 22.05.2025 06:07, Klemens Nanni пишет:
> > 15.05.2025 13:05, Mark Kettenis пишет:
> >>> Date: Thu, 15 May 2025 11:22:17 +0200
> >>> From: Claudio Jeker <cje...@diehard.n-r-g.com>
> >>>
> >>> On Thu, May 15, 2025 at 06:28:42PM +1000, Jonathan Matthew wrote:
> >>>> On Tue, May 13, 2025 at 07:55:03AM +0200, Otto Moerbeek wrote:
> >>>>> On Mon, May 12, 2025 at 08:07:11PM +0200, Sebastien Marie wrote:
> >>>>>
> >>>>>>> I suppose the same could occurs with lld (untested for now).
> >>>>>>
> >>>>>> I confirm it is the same problem with lld.
> >>>>>>
> >>>>>> $ cd /usr/share/relink/kernel/GENERIC.MP
> >>>>>> $ ld -T ld.script -X --warn-common -nopie -o /tmp/newbsd *.o && echo ok
> >>>>>>
> >>>>>> /tmp: write failed, file system is full
> >>>>>> ok
> >>>>>> $ ls -l /tmp/newbsd
> >>>>>> -rwxr-xr-x 1 semarie wheel 236434608 May 12 20:05 /tmp/newbsd*
> >>>>>>
> >>>>>> And my dmesg has the following:
> >>>>>> uvn_flush: obj=0xfffffd86e3311608, offset=0x16b0000. error during
> >>>>>> pageout.
> >>>>>> uvn_flush: WARNING: changes to page may be lost!
> >>>>>
> >>>>> So this code is using mmapped files for writing, which makes proper
> >>>>> error handling extremely difficult or even impossible. Best bet is
> >>>>> making sure enough space is available before starting.
> >>>>
> >>>> lld has a --no-mmap-output-file option that causes it to use plain
> >>>> write(2)
> >>>> calls to generate the output file. Perhaps it'd be worth using that for
> >>>> kernel linking and other stuff we relink at boot time?
> >>>
> >>> Maybe that should be the default. Having lld produce bad binaries but exit
> >>> 0 is just very wrong. Not sure if this a problem that only manifests on
> >>> OpenBSD since there is no unified buffer cache or if other systems would
> >>> hit the same issue as well. As Otto mentioned detection IO errors when
> >>> using mmap to write files is not trivial.
> >>
> >> I think the same problem exists on other OSes, even those with a
> >> unified buffer cache. I suppose lld(1) could use msync(2) (with the
> >> MS_SYNC) flag to make sure everything lands on disk correctly. But
> >> that obviously would remove some of the benefits of using mmap(),
> >> namely the async completion of the writes.
> >>
> >> It would be intersting to see what the impact on build times of
> >> changing the defaults would be. But I'm somewhat hesitant to change
> >> the default since the --no-mmap-output-file code path isn't tested
> >> much on other OSes.
> >
> > Shall we first try it for kernels only?
> >
> > # make && make install && reboot
> > ld -T ld.script -X --warn-common -nopie --no-mmap-output-file -o bsd
> > ${SYSTEM_HEAD} vers.o ${OBJS}
> > text data bss dec hex
> > 26918218 492744 1351680 28762642 1b6e212
> > mv bsd bsd.gdb
> > ctfstrip -S -o bsd bsd.gdb
> >
> > $ cat /usr/share/relink/kernel/GENERIC.MP/relink.log
> > (SHA256) /bsd: OK
> > LD="ld" sh makegap.sh 0xcccccccc gapdummy.o
> > ld -T ld.script -X --warn-common -nopie --no-mmap-output-file -o newbsd
> > ${SYSTEM_HEAD} vers.o ${OBJS}
> > text data bss dec hex
> > 26908374 489800 1347584 28745758 1b6a01e
> > mv newbsd newbsd.gdb
> > [...]
> >
> > This also effects installs and upgrades.
>
> Any thoughts on doing this for all architectures using clang?
> Looks like that'd be <bsd.own.mk> CLANG_ARCH modulo sparc64.
>
> >
> > Index: sys/arch/amd64/conf/Makefile.amd64
> > ===================================================================
> > RCS file: /cvs/src/sys/arch/amd64/conf/Makefile.amd64,v
> > diff -u -p -r1.142 Makefile.amd64
> > --- sys/arch/amd64/conf/Makefile.amd64 5 May 2025 20:43:32 -0000
> > 1.142
> > +++ sys/arch/amd64/conf/Makefile.amd64 22 May 2025 02:44:05 -0000
> > @@ -111,6 +111,8 @@ COPTIMIZE?= -O2
> > CFLAGS= ${DEBUG} ${CWARNFLAGS} ${CMACHFLAGS} ${COPTIMIZE}
> > ${COPTS} ${PIPE}
> > AFLAGS= -D_LOCORE -x assembler-with-cpp ${CWARNFLAGS}
> > ${CMACHFLAGS}
> > LINKFLAGS= -T ld.script -X --warn-common -nopie
> > +# propagate failure like ENOSPC on relink
> > +LINKFLAGS+= --no-mmap-output-file
> >
> > HOSTCC?= ${CC}
> > HOSTED_CPPFLAGS=${CPPFLAGS:S/^-nostdinc$//}
> >
>
