Attachment 22376 Details for Bug 60883 – Патч alt/glibc.spec (p11): включить multiarch (IFUNC) для i586, сборка как i686

[patch] Патч alt/glibc.spec (p11): включить multiarch (IFUNC) для i586, сборка как i686

glibc-2.38.0.223.f053ff-alt-i586-multiarch.patch (text/plain), 1.78 KB, created by mail on 2026-10-09 16:22:58 MSK

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Created: 2026-10-09 16:22:58 MSK

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>Subject: [PATCH] alt/glibc.spec: enable multiarch (IFUNC) for i586 by building as i686
>
>On ALT p11, i586-glibc-core is built for the i586 target with multiarch
>disabled, so memcpy/memmove/memset/strlen/strcmp/memcmp and the other string
>functions are the old generic i586 code (plain FUNC symbols, no IFUNC).
>The i586 memcpy reads the destination buffer before writing it, which makes
>32-bit applications that copy large amounts of data (Steam games, e.g.
>Half-Life 2 with Mesa/radeonsi) run 6-9 times slower than with the Fedora or
>freedesktop-sdk 32-bit glibc (20-30 FPS vs 180 FPS on the same machine).
>
>The i386 IFUNC variants are in sysdeps/i386/i686/multiarch, which is only used
>when configured for an i686 target; simply adding --enable-multi-arch for
>%ix86 fails to link ("undefined reference to __memcmp_ia32").
>
>Enable multiarch on %ix86 and configure it with --build/--host=i686-alt-linux.
>A test build of glibc-2.38.0.223.f053ff-alt1.p11.1 in hasher for i586 succeeds
>and exports 48 IFUNC symbols (same set as the freedesktop-sdk 26.08 i386 libc).
>Note: this makes the library require i686 (cmov) CPUs; real i586-only
>processors would no longer be supported by this package.
>
>---
>--- a/alt/glibc.spec	2026-10-09 15:28:33.154117397 +0500
>+++ b/alt/glibc.spec	2026-10-09 15:28:33.164537673 +0500
>@@ -24,7 +24,9 @@
> %def_with locales
> %def_enable memusagestat
> 
>-%ifarch x86_64
>+# IFUNC variants (SSE2/AVX) of memcpy/memmove/memset/strlen/strcmp/... live in
>+# sysdeps/i386/i686/multiarch, so multiarch on %ix86 requires an i686 target.
>+%ifarch x86_64 %ix86
> %def_enable multiarch
> %else
> %def_disable multiarch
>@@ -361,6 +363,9 @@
> %global optflags_lto %nil
> 
> %configure \
>+%ifarch %ix86
>+	--build=i686-alt-linux --host=i686-alt-linux \
>+%endif
> 	--disable-crypt \
> 	--disable-profile \
> 	--enable-bind-now \

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