Re: [PATCH] x86/ACPI/cstate: Output AMD on APCI C1 FFH MWAIT AMD systems

From: Pavel Machek <pavel@ucw.cz>
To: Prarit Bhargava <prarit@redhat.com>
Cc: linux-kernel@vger.kernel.org, Len Brown <lenb@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH] x86/ACPI/cstate: Output AMD on APCI C1 FFH MWAIT AMD systems
Date: Wed, 8 Aug 2018 21:58:56 +0200	[thread overview]
Message-ID: <20180808195856.GA20912@amd> (raw)
In-Reply-To: <20180808174735.3114-1-prarit@redhat.com>

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On Wed 2018-08-08 13:47:35, Prarit Bhargava wrote:
> commit 5209654a46ee ("x86/ACPI/cstate: Allow ACPI C1 FFH MWAIT use on AMD
> systems") allows use of FFH for ACPI C1 but tools like cpupower and turbostat
> display INTEL for the cstate description.
> 
> Output "AMD" for AMD systems with FFH for ACPI C1.

Um, is it good idea?

First, you are changing kernel API.

> @@ -107,9 +108,14 @@ static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
>  			"Monitor-Mwait will be used to enter C-%d state\n",
>  			cx->type);
>  	}
> -	snprintf(cx->desc,
> -			ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
> -			cx->address);
> +	if (c->x86_vendor == X86_VENDOR_INTEL)
> +		snprintf(cx->desc,
> +			 ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
> +			 cx->address);
> +	else
> +		snprintf(cx->desc,
> +			 ACPI_CX_DESC_LEN, "ACPI FFH AMD MWAIT 0x%x",
> +			 cx->address);

Second, I read it as "Intel MWAIT" instruction is used. Yes, AMD cpu can
use Intel MWAIT, too...

Third, there are more CPU vendors out there.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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