cpuinfo: Use auxv for AltiVec on Linux if possible #12955
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The SIGILL handler is not very reliable and can cause crashes. Linux provides the CPU's AltiVec support status in getauxval.
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This is merged to main and cherry-picked for the next SDL2 and SDL3 releases. However, I think this will fail to build if altivec blitters is defined and |
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Hmm, yes, logically it would, but is it possible to have a environment where I suppose that the |
| @@ -115,7 +115,7 @@ | |||
| #define CPU_CFG2_LSX (1 << 6) | |||
| #define CPU_CFG2_LASX (1 << 7) | |||
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| #if defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP) && !defined(SDL_PLATFORM_MACOS) && !defined(SDL_PLATFORM_OPENBSD) && !defined(SDL_PLATFORM_FREEBSD) | |||
| #if defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP) && !defined(SDL_PLATFORM_MACOS) && !defined(SDL_PLATFORM_OPENBSD) && !defined(SDL_PLATFORM_FREEBSD) && (defined(SDL_PLATFORM_LINUX) && !defined(HAVE_GETAUXVAL)) | |||
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| #if defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP) && !defined(SDL_PLATFORM_MACOS) && !defined(SDL_PLATFORM_OPENBSD) && !defined(SDL_PLATFORM_FREEBSD) && (defined(SDL_PLATFORM_LINUX) && !defined(HAVE_GETAUXVAL)) | |
| #if defined(SDL_ALTIVEC_BLITTERS) && defined(HAVE_SETJMP) && !defined(SDL_PLATFORM_MACOS) && !defined(SDL_PLATFORM_OPENBSD) && !defined(SDL_PLATFORM_FREEBSD) && !(defined(SDL_PLATFORM_LINUX) && defined(HAVE_GETAUXVAL)) |
Otherwise this will be disabled on all non-Linux platforms.
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Ah, you're right - thanks! I'll fix this up in a few hours.
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Ah, you're right - thanks! I'll fix this up in a few hours.
Done in 29d2116
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Done in 29d2116
Needs applying to release-3.2.x and possibly to SDL2 and release-2.32.x as well
Description
The SIGILL handler is not very reliable and can cause crashes.
Linux provides the CPU's AltiVec support status in getauxval.
Existing Issue(s)
None seem to be reported to SDL itself. A few distro-specific bugs have been submitted. We were notified by a user trying to run SuperTux on Wii U, which has a PPC 750 (like G3) which does not support AltiVec. They received a crash (with SIGILL) before this patch, and a working game after this patch.
Note that SuperTux uses SDL 2, and the patch was applied to our Espresso SDL 2 package. I wasn't able to find any SDL 3 clients to easily test on a Wii U, so I can't say for sure SDL 3 has the same bug nor can I say this is 100% guaranteed to work, but it seemed the right thing to submit here anyway. I'm not sure if there is still a way to submit fixes for SDL 2, but it would be great to have this there too, if there is another patch release planned.