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Date: Sun, 30 May 2010 17:18:21 +0200 From: Geert Uytterhoeven <geert@...ux-m68k.org> To: Borislav Petkov <bp@...en8.de>, Geert Uytterhoeven <geert@...ux-m68k.org>, Toralf Förster <toralf.foerster@....de>, Borislav Petkov <borislav.petkov@....com>, "H. Peter Anvin" <hpa@...or.com>, user-mode-linux-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org Subject: Re: current git kernel crashes UML system during boot On Sun, May 30, 2010 at 17:02, Borislav Petkov <bp@...en8.de> wrote: > From: Geert Uytterhoeven <geert@...ux-m68k.org> > Date: Sun, May 30, 2010 at 01:57:05PM +0200 > >> On Sun, May 30, 2010 at 13:39, Geert Uytterhoeven <geert@...ux-m68k.org> wrote: >> > 2010/5/27 Toralf Förster <toralf.foerster@....de>: >> >> I bisected it to this : >> >> > After fixing the missing/superfluous slab inclusion issues, I bisected >> > it further to >> > >> > commit d61931d89be506372d01a90d1755f6d0a9fafe2d >> > Author: Borislav Petkov <borislav.petkov@....com> >> > Date: Fri Mar 5 17:34:46 2010 +0100 >> > >> > x86: Add optimized popcnt variants >> > >> > Add support for the hardware version of the Hamming weight function, >> > popcnt, present in CPUs which advertize it under CPUID, Function >> > 0x0000_0001_ECX[23]. On CPUs which don't support it, we fallback to the >> > default lib/hweight.c sw versions. >> > >> > A synthetic benchmark comparing popcnt with __sw_hweight64 showed almost >> > a 3x speedup on a F10h machine. >> > >> > Signed-off-by: Borislav Petkov <borislav.petkov@....com> >> > LKML-Reference: <20100318112015.GC11152@...ab> >> > Signed-off-by: H. Peter Anvin <hpa@...or.com> >> > >> > I reverted that commit on top of current mainline (and fixed up the >> > conflicts), and now >> > it boots again. >> >> I tried adding >> >> config ARCH_HWEIGHT_CFLAGS >> string >> default "-fcall-saved-ecx -fcall-saved-edx" if !64_BIT >> default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx >> -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 >> -fcall-saved-r11" if 64_BIT >> >> to arch/um/Kconfig.x86. Now it got a bit further, but it still crashes: > > Ok, this is a kinda stab in the dark but from what I could decypher > from the include hell, one possible fix should be if UML didn't include > <arch/x86/include/asm/arch_hweight.h> but use the software hweight > version only. > > Can you guys check whether the following fixes the issue? Works, thanks! BTW, if you want to check yourself: make ARCH=um defconfig make ACH=um ./linux If it panics because it cannot mount the root file system, it works. > diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h > index 545776e..c9dad12 100644 > --- a/arch/x86/include/asm/bitops.h > +++ b/arch/x86/include/asm/bitops.h > @@ -444,7 +444,11 @@ static inline int fls(int x) > > #define ARCH_HAS_FAST_MULTIPLIER 1 > > +#ifdef CONFIG_UML > +#include <asm-generic/bitops/arch_hweight.h> > +#else > #include <asm/arch_hweight.h> > +#endif > > #include <asm-generic/bitops/const_hweight.h> Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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