El 20/2/16 a les 3:41, Kevin O'Connor ha escrit: > On Tue, Feb 16, 2016 at 06:21:10PM +0100, Roger Pau Monné wrote: >> El 16/2/16 a les 17:33, Kevin O'Connor ha escrit: >>> On Tue, Feb 16, 2016 at 01:56:26PM +0100, Roger Pau Monne wrote: >>>> According to the output from readelf, the .text section should be aligned >>>> to >>>> 16: >>>> >>>> Section Headers: >>>> [Nr] Name Type Addr Off Size ES Flg Lk >>>> Inf Al >>>> [ 0] (null) NULL 00000000 000000 000000 00 0 >>>> 0 0 >>>> [ 1] .text PROGBITS 000de300 000300 021d00 00 AX 0 >>>> 0 16 >>>> [...] >>>> >>>> This however doesn't seem to be enforced when the relocations are >>>> generated. >>>> The following patch tries to address this by making sure the space used for >>>> the relocations it also aligned to the same value as the .text section. >>> >>> Thanks. What goes wrong if the .text section is not aligned? The >>> code has already been assigned physical addresses by this point, so it >>> should not impact the runtime code. >> >> It seems like ELF toolchain objcopy chokes if a section address is not >> aligned to the alignment specified by the section, see: >> >> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=207170 >> >> The snippet shown above has addr aligned to 16 (which matches latest >> upstream), so it's not a problem, but the current SeaBIOS version >> shipped in Xen 4.5 (1.7.5 IIRC) ends up with an addr that's not a >> multiple of 16, as shown in the bug report, and objcopy complains with: >> >> objcopy: elf_update() failed: Layout constraint violation > > Thanks. I agree it should be fixed. However, I think there are a few > other cases that could cause the ".text" section alignment to be off. > Are you okay with the patch below instead?
Yes, looks fine to me. AFAICT SeaBIOS packs all the sections (.text, .data, .rodata) ibnside of the .text section, which I didn't realize before. Roger _______________________________________________ SeaBIOS mailing list [email protected] http://www.seabios.org/mailman/listinfo/seabios
