2005-04-27 01:17:48

by Zwane Mwaikambo

Subject: [PATCH] cpuid x87 bit on AMD falsely marked as PNI

http://bugme.osdl.org/show_bug.cgi?id=4426

vendor_id : AuthenticAMD
cpu family : 6
model : 10
model name : AMD Athlon(tm) XP
stepping : 0
cpu MHz : 2204.807
<snipped>
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 mmx fxsr sse pni syscall mmxext 3dnowext 3dnow
bogomips : 4358.14

We're marking bit 0 of extended function 0x80000001 cpuid as PNI support
on AMD processors, when it actually denotes x87 FPU present. Patch for
i386 and x86_64 below.

Signed-off-by: Zwane Mwaikambo <[email protected]>

Index: linux-2.6.12-rc2-mm3/arch/i386/kernel/cpu/proc.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.12-rc2-mm3/arch/i386/kernel/cpu/proc.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 proc.c
--- linux-2.6.12-rc2-mm3/arch/i386/kernel/cpu/proc.c 17 Apr 2005 14:03:42 -0000 1.1.1.1
+++ linux-2.6.12-rc2-mm3/arch/i386/kernel/cpu/proc.c 27 Apr 2005 00:46:18 -0000
@@ -25,7 +25,7 @@ static int show_cpuinfo(struct seq_file
"fxsr", "sse", "sse2", "ss", "ht", "tm", "ia64", "pbe",

/* AMD-defined */
- "pni", NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, "syscall", NULL, NULL, NULL, NULL,
NULL, NULL, NULL, "mp", "nx", NULL, "mmxext", NULL,
NULL, "fxsr_opt", NULL, NULL, NULL, "lm", "3dnowext", "3dnow",
Index: linux-2.6.12-rc2-mm3/arch/x86_64/kernel/setup.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.12-rc2-mm3/arch/x86_64/kernel/setup.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 setup.c
--- linux-2.6.12-rc2-mm3/arch/x86_64/kernel/setup.c 17 Apr 2005 14:03:51 -0000 1.1.1.1
+++ linux-2.6.12-rc2-mm3/arch/x86_64/kernel/setup.c 27 Apr 2005 00:46:31 -0000
@@ -1103,7 +1103,7 @@ static int show_cpuinfo(struct seq_file
"fxsr", "sse", "sse2", "ss", "ht", "tm", "ia64", NULL,

/* AMD-defined */
- "pni", NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, "syscall", NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, "nx", NULL, "mmxext", NULL,
NULL, "fxsr_opt", NULL, NULL, NULL, "lm", "3dnowext", "3dnow",

2005-04-27 07:07:45

by Denis Vlasenko

Subject: Re: [PATCH] cpuid x87 bit on AMD falsely marked as PNI

On Wednesday 27 April 2005 04:20, Zwane Mwaikambo wrote:
> http://bugme.osdl.org/show_bug.cgi?id=4426
>
> vendor_id : AuthenticAMD
> cpu family : 6
> model : 10
> model name : AMD Athlon(tm) XP
> stepping : 0
> cpu MHz : 2204.807
> <snipped>
> cpuid level : 1
> wp : yes
> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
> pat pse36 mmx fxsr sse pni syscall mmxext 3dnowext 3dnow
> bogomips : 4358.14
>
> We're marking bit 0 of extended function 0x80000001 cpuid as PNI support
> on AMD processors, when it actually denotes x87 FPU present. Patch for
> i386 and x86_64 below.

I just yesterday noticed that my Athlon (non-64bit) has 'pni' in CPU
flags and was very puzzled.

Thanks Zwane.
--
vda