linux-kernel - Re: [PATCH 01/29] x86: perfcounter: remove X86_FEATURE_ARCH

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Date:	Wed, 29 Apr 2009 13:21:50 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Robert Richter <robert.richter@....com>,
	"H. Peter Anvin" <hpa@...or.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/29] x86: perfcounter: remove
	X86_FEATURE_ARCH_PERFMON flag for AMD cpus


* Robert Richter <robert.richter@....com> wrote:

> X86_FEATURE_ARCH_PERFMON is an Intel hardware feature that does not
> work on AMD CPUs. The flag is now only used in Intel specific code
> (especially initialization).
> 
> Signed-off-by: Robert Richter <robert.richter@....com>
> ---
>  arch/x86/kernel/cpu/amd.c          |    4 ----
>  arch/x86/kernel/cpu/perf_counter.c |    6 +++---
>  2 files changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index fd69c51..7e4a459 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -420,10 +420,6 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
>  	if (c->x86 >= 6)
>  		set_cpu_cap(c, X86_FEATURE_FXSAVE_LEAK);
>  
> -	/* Enable Performance counter for K7 and later */
> -	if (c->x86 > 6 && c->x86 <= 0x11)
> -		set_cpu_cap(c, X86_FEATURE_ARCH_PERFMON);

might make sense to introduce a 'virtual CPU ID flag' for it like we 
do it in other cases, to signal that we support perfcounters on this 
CPU.

	Ingo
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