El 23/2/16 a les 15:53, Kevin O'Connor ha escrit: > 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.
Thanks, I would also like to request this fix to be backported to stable branches. Should I send a formal request, or is this email enough? Ideally I would like to see it applied to 1.9, 1.8 and 1.7.5. Roger. _______________________________________________ SeaBIOS mailing list [email protected] http://www.seabios.org/mailman/listinfo/seabios
