Attachment 313161 Details for Bug 197455 – fix for the f00f bug detection

fix for the f00f bug detection

linux-2.6-x86-f00f-bug-detection-fix.patch (text/plain), 1.33 KB, created by Chuck Ebbert on 2008-08-01 04:51:52 UTC

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Creator: Chuck Ebbert

Created: 2008-08-01 04:51:52 UTC

Size: 1.33 KB

patch

obsolete

>From: Krzysztof Helt <krzysztof.h1@wp.pl>
>[http://lkml.org/lkml/2008/7/31/91]
>
>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");
> }
>

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