On Mon, Feb 22, 2016 at 12:07:00PM +0100, Roger Pau Monné wrote: > 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.
Thanks, I committed the change. -Kevin _______________________________________________ SeaBIOS mailing list SeaBIOS@seabios.org http://www.seabios.org/mailman/listinfo/seabios
