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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
	jgross@suse.com, Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Len Brown <lenb@kernel.org>, Alex Chiang <achiang@hp.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
	linux-acpi@vger.kernel.org
Subject: Re: [PATCH 1/3] acpi/processor: fix evaluating _PDC method when running as Xen dom0
Date: Fri, 2 Dec 2022 18:06:26 +0100	[thread overview]
Message-ID: <CAJZ5v0hrdwUNOELXM5zxtTeavp+_o7TbkCRBjZVqvQVxt4QBnA@mail.gmail.com> (raw)
In-Reply-To: <Y4opuLnLIT3v9Aa7@Air-de-Roger>

On Fri, Dec 2, 2022 at 5:37 PM Roger Pau Monné <roger.pau@citrix.com> wrote:
>
> On Fri, Dec 02, 2022 at 08:17:56AM -0800, Dave Hansen wrote:
> > On 12/2/22 04:24, Roger Pau Monné wrote:
> > > On the implementation side, is the proposed approach acceptable?
> > > Mostly asking because it adds Xen conditionals to otherwise generic
> > > ACPI code.
> >
> > That's a good Rafael question.

Sorry for joining late, but first off _PDC has been deprecated since
ACPI 3.0 (2004) and it is not even present in ACPI 6.5 any more.

It follows from your description that _PDC is still used in the field,
though, after 18 years of deprecation.  Who uses it, if I may know?

> > But, how do other places in the ACPI code handle things like this?
>
> Hm, I don't know of other places in the Xen case, the only resource
> in ACPI AML tables managed by Xen are Processor objects/devices AFAIK.
> The rest of devices are fully managed by the dom0 guest.
>
> I think such special handling is very specific to Xen, but maybe I'm
> wrong and there are similar existing cases in ACPI code already.
>
> We could add some kind of hook (iow: a function pointer in some struct
> that could be filled on a implementation basis?) but I didn't want
> overengineering this if adding a conditional was deemed OK.

What _PDC capabilities specifically do you need to pass to the
firmware for things to work correctly?

What platforms are affected?

  reply	other threads:[~2022-12-02 17:06 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-21 10:21 [PATCH 0/3] xen: ACPI processor related fixes Roger Pau Monne
2022-11-21 10:21 ` [PATCH 1/3] acpi/processor: fix evaluating _PDC method when running as Xen dom0 Roger Pau Monne
2022-11-21 14:02   ` Jan Beulich
2022-11-21 14:29     ` Roger Pau Monné
2022-11-21 14:51       ` Jan Beulich
2022-11-21 15:09         ` Roger Pau Monné
2022-11-29 16:01   ` Roger Pau Monné
2022-11-29 17:43   ` Dave Hansen
2022-11-30 15:53     ` Roger Pau Monné
2022-11-30 16:48       ` Dave Hansen
2022-12-02 12:24         ` Roger Pau Monné
2022-12-02 16:17           ` Dave Hansen
2022-12-02 16:37             ` Roger Pau Monné
2022-12-02 17:06               ` Rafael J. Wysocki [this message]
2022-12-09 10:12                 ` Roger Pau Monné
2023-01-30  9:21   ` Josef Johansson
2023-02-03  7:05     ` Jan Beulich
2023-02-03 13:58       ` Josef Johansson
2022-11-21 10:21 ` [PATCH 2/3] acpi/processor: sanitize _PDC buffer bits " Roger Pau Monne
2022-11-21 14:10   ` Jan Beulich
2022-11-21 14:13     ` Jan Beulich
2022-11-21 15:03     ` Roger Pau Monné
2023-06-14 19:57       ` Jason Andryuk
2023-06-16 14:39         ` Roger Pau Monné
2022-11-21 10:21 ` [PATCH 3/3] xen/acpi: upload power and performance related data from a PVH dom0 Roger Pau Monne
2023-01-30  9:10   ` Josef Johansson
2023-03-15 11:39     ` Roger Pau Monné
2023-03-16  7:54       ` Josef Johansson
2023-03-16 10:06         ` Roger Pau Monné
2022-11-21 14:20 ` [PATCH 0/3] xen: ACPI processor related fixes Jan Beulich
2022-11-21 16:27   ` Roger Pau Monné

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