linux-kernel - Re: [PATCH v3] turbostat: Read extended processor family from CPUID

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Date:   Fri, 27 Jul 2018 12:49:50 -0400
From:   Len Brown <lenb@...nel.org>
To:     Calvin Walton <calvin.walton@...stin.ca>
Cc:     Linux PM list <linux-pm@...r.kernel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] turbostat: Read extended processor family from CPUID

Applied -- thanks!
On Fri, Jul 27, 2018 at 7:50 AM Calvin Walton <calvin.walton@...stin.ca> wrote:
>
> This fixes the reported family on modern AMD processors (e.g. Ryzen,
> which is family 0x17). Previously these processors all showed up as
> family 0xf.
>
> See the document
> https://support.amd.com/TechDocs/56255_OSRR.pdf
> section CPUID_Fn00000001_EAX for how to calculate the family
> from the BaseFamily and ExtFamily values.
>
> This matches the code in arch/x86/lib/cpu.c
>
> Signed-off-by: Calvin Walton <calvin.walton@...stin.ca>
> ---
>
> v3: Having just looked at the arch/x86/lib/cpu.c code again, I realized
> that it *didn't* actually match - the kernel code uses family >= 6 for
> applying the extended model number, while I was applying it only to
>  family == 6 or family >= 0xf. Change that to match for consistency.
>
> v2: I'm still working on updating the RAPL patch on top of the changes for
> v4.18, but this CPUID fix doesn't have to wait.
>
>  tools/power/x86/turbostat/turbostat.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
> index bd9c6b31a504..ed024deed36f 100644
> --- a/tools/power/x86/turbostat/turbostat.c
> +++ b/tools/power/x86/turbostat/turbostat.c
> @@ -4031,7 +4031,9 @@ void process_cpuid()
>         family = (fms >> 8) & 0xf;
>         model = (fms >> 4) & 0xf;
>         stepping = fms & 0xf;
> -       if (family == 6 || family == 0xf)
> +       if (family == 0xf)
> +               family += (fms >> 20) & 0xff;
> +       if (family >= 6)
>                 model += ((fms >> 16) & 0xf) << 4;
>
>         if (!quiet) {
> --
> 2.18.0
>


-- 
Len Brown, Intel Open Source Technology Center