Re: Bug#1092890: mesa: regression in 24.3: software rendering crashes on ppc64el with segmentation fault

Dmitry Shachnev <[email protected]> Sun, 2 Feb 2025 18:01:48 +0300

Newsgroups	gmane.linux.debian.ports.powerpc
Message-ID	<[email protected]>

On Wed, Jan 29, 2025 at 11:54:34PM +0300, Dmitry Shachnev wrote:
> In other news, I tried to use different linkers and linker options. With all
> linkers, it crashes, but in a bit different ways:
>
> - bfd (default): jump happens to stderr().
>
> - gold: jump happens to some incorrect place in libgallium-24.3.4.so:
>   https://paste.debian.net/1347044/
>   https://paste.debian.net/1347045/
>
> - lld: jump happens to 0x0.
>
> - bfd with -Wl,-z,now: *** stack smashing detected *** but in the same
>   location, when attempting to do driSwapBuffers(pdraw->dri_drawable).
>
> Also I tried a different compiler (clang), and did not notice any difference
> compared to gcc.
>
> In case someone else wants to take a look at this, here is how I test it:
> [...]

First, I found an easier way to reproduce this issue. Installing mesa-utils
package and running "xvfb-run -a glxgears" is enough to trigger it.

Second, I noticed that building without -DUSE_PPC64LE_ASM makes the issue
go away. Maybe there is some problem with the assembly (entry_ppc64le_tls.h)
but I can’t say what exactly. Anyway, I submitted a merge request to disable
assembly for now:
https://salsa.debian.org/xorg-team/lib/mesa/-/merge_requests/52

Dear Debian powerpc porters, if someone has an idea what happens here and
whether it can be fixed in a better way, any help would be welcome! Please see
my previous comments on this bug for more details.

--
Dmitry Shachnev

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