linux-kernel - Re: [PATCH] x86: enable PAT for amd k8 and fam10h

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Date:	Mon, 24 Mar 2008 19:22:42 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"kernel list" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: enable PAT for amd k8 and fam10h

On Mon, Mar 24, 2008 at 6:29 PM, H. Peter Anvin <hpa@...or.com> wrote:
> Yinghai Lu wrote:
>  > [PATCH] x86: enable PAT for amd k8 and fam10h
>  >
>  > make known_pat_cpu to think amd k8 and fam10h is ok too.
>  >
>  > also make tom2 below to be WRBACK
>  >
>
> > diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
>  > index f74505f..a9e1a27 100644
>  > --- a/arch/x86/mm/pat.c
>  > +++ b/arch/x86/mm/pat.c
>  > @@ -49,6 +49,12 @@ static int pat_known_cpu(void)
>  >                       return 1;
>  >               }
>  >       }
>  > +     if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
>  > +          boot_cpu_data.x86 >= 0xf && boot_cpu_data.x86 <= 0x11) {
>  > +             if (cpu_has_pat) {
>  > +                     return 1;
>  > +             }
>  > +     }
>  >
>  >       pat_wc_enabled = 0;
>  >       printk(KERN_INFO "CPU and/or kernel does not support PAT.\n");
>
>  This really should be handled through a CPU flag.  Specifically, it
>  should be handled by disabling the PAT flag if PAT is unusable or
>  suspect of being unusable; it should *NOT* be stashed away in a
>  completely separate piece of code.

PAT patches in x86.git latest, only support some intel CPUs.

        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
            (boot_cpu_data.x86 == 0xF ||
             (boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model >= 15))) {
                if (cpu_has_pat) {
                        return 1;
                }
        }

should be moved to setup_64.c?

YH
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