From: Borislav Petkov <bp@alien8.de>
To: Stephen Horvath <s.horvath@outlook.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/tsc: Read AMD CPU frequency from Core::X86::Msr::PStateDef
Date: Thu, 14 Aug 2025 17:25:50 +0200 [thread overview]
Message-ID: <20250814152550.GAaJ3__hIHnOBhKGWN@fat_crate.local> (raw)
In-Reply-To: <20250813112020.345622-1-s.horvath@outlook.com.au>
On Wed, Aug 13, 2025 at 11:23:38AM +0000, Stephen Horvath wrote:
> + /* The PPR defines the core multiplier as CpuFid * 25MHz */
> + p0_freq = cpufid * 25;
As someone already pointed out:
PPR Vol 1 for AMD Family 1Ah Model 02h C1
...
MSRC001_006[4...B] [P-state [7:0]] (Core::X86::Msr::PStateDef)
...
CpuFid[11:0]: core frequency ID.
FFFh- <Value>*5
010h
So we need to do per-family checks here.
Not sure if that is worth it, frankly.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2025-08-14 15:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-13 11:23 [PATCH] x86/tsc: Read AMD CPU frequency from Core::X86::Msr::PStateDef Stephen Horvath
2025-08-14 6:36 ` kernel test robot
2025-08-14 7:40 ` Stephen Horvath
2025-08-14 15:25 ` Borislav Petkov [this message]
2025-08-15 1:53 ` Stephen Horvath
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