[syslinux] [PATCH] Fix for crash with certain EFIs

Ady Ady
Wed, 19 Oct 2016 10:05:25 -0000

> Hi Ady,
>
> Would it work if we removed "ifdef EFI_BUILD" condition and just
add
> -mno-red-zone for all x86_64 builds? If not, do you have any ideas how
> to pass this flag?
>
> This could work, because the patch is adding the -mno-red-zone flag
> only for x86_64 builds, which are only used in the form of the efi64
> target. The efi32 and bios targets are both 32-bit.
>
> BTW. I also tried 6.04-pre1 and top of tree on the systems where the
> problem occurs and syslinux would crash, unless it was rebuilt with
> the -mno-red-zone flag.
>
> Best Regards,
> - Chris
>

The last time the red zone flag was modified in the code was in commit:


repo.or.cz/syslinux.git/commit/7d70885d22e4474407637026c1af12a253281407


during 2015Nov. At that time, "EFI_BUILD" was not only in use but was
also expanded / passed down to additional makefiles (by the commit just
before that one).

Then there is this email from Gene:

 http://www.syslinux.org/archives/2015-December/024641.html

but I do not know to which exact commit he was referring when he wrote
"pushed".

Then "EFI_BUILD" was completely removed by commit:


repo.or.cz/syslinux.git/commit/7284652bbd41a0a37ac7146c5e7ae807abdf5748


during 2016Feb.

According to some reports, the current use of the -mno-red-zone flag
seems to not be enough / correct. It is there, and it is not using
"EFI_BUILD" at this time, but the resulting binaries seem to be
failing, at least in certain cases.

It would be interesting to have a valid patch for the current git
master head, or at least for 6.04-pre1.

Regards,
Ady.

PS: Please avoid top-posting.