Messages in this thread | | | Date | Thu, 31 Jul 2008 14:49:20 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] x86: fdiv bug detection fix |
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On Thu, 31 Jul 2008 23:43:44 +0200 Krzysztof Helt <krzysztof.h1@wp.pl> wrote:
> From: Krzysztof Helt <krzysztof.h1@wp.pl> > > The fdiv detection code writes s32 integer into > the boot_cpu_data.fdiv_bug. > However, the boot_cpu_data.fdiv_bug is only char (s8) > field so the detection overwrites already set fields for > other bugs, e.g. the f00f bug field. > > Use local s32 variable to receive result. > > Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl> > --- > > This is a partial fix to Bugzilla #9928 - fixes wrong > information about the f00f bug (tested) and probably > for coma bug (I have no cpu to test this). > > diff -urp linux-alsa/arch/x86/kernel/cpu/bugs.c linux-new/arch/x86/kernel/cpu/bugs.c > --- linux-alsa/arch/x86/kernel/cpu/bugs.c 2008-07-31 12:40:31.000000000 +0200 > +++ linux-new/arch/x86/kernel/cpu/bugs.c 2008-07-31 23:24:07.722657435 +0200 > @@ -50,6 +50,8 @@ static double __initdata y = 3145727.0; > */ > static void __init check_fpu(void) > { > + s32 fdiv_bug; > + > if (!boot_cpu_data.hard_math) { > #ifndef CONFIG_MATH_EMULATION > printk(KERN_EMERG "No coprocessor found and no math emulation present.\n"); > @@ -74,8 +76,10 @@ static void __init check_fpu(void) > "fistpl %0\n\t" > "fwait\n\t" > "fninit" > - : "=m" (*&boot_cpu_data.fdiv_bug) > + : "=m" (*&fdiv_bug) > : "m" (*&x), "m" (*&y)); > + > + boot_cpu_data.fdiv_bug = fdiv_bug; > if (boot_cpu_data.fdiv_bug) > printk("Hmm, FPU with FDIV bug.\n"); > }
hm, the code seems to have been that way for quite some time. I wonder why nobody noticed this before.
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