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From: "Anthony PERARD" <anthony.perard@citrix.com>
To: Gary Lin <glin@suse.com>
Cc: <devel@edk2.groups.io>,
	Ard Biesheuvel <ardb+tianocore@kernel.org>,
	Jordan Justen <jordan.l.justen@intel.com>,
	Julien Grall <julien@xen.org>, Jim Fehlig <jfehlig@suse.com>
Subject: Re: [edk2-devel] [RFC PATCH] OvmfPkg/OvmfXen: set PcdAcpiS3Enable at initialization
Date: Tue, 27 Jul 2021 11:57:07 +0100	[thread overview]
Message-ID: <YP/mg2PEIClM112i@perard> (raw)
In-Reply-To: <YPfFLirF3rK36Gsp@GaryWorkstation>

On Wed, Jul 21, 2021 at 02:56:46PM +0800, Gary Lin wrote:
> BTW, it seems to me that QEMU fwcfg is only used for Xen Direct Kernel
> Boot. However, per xl.cfg manpage, it's possible to turn on or off S3
> support by setting "acpi_s3" in xl.cfg, but PcdAcpiS3Enable wasn't set
> in the current OvmfXen implementation. Just wonder how xl passes the S3
> support bit to OvmfXen.

It doesn't. "acpi_s3" doesn't have any control over PcdAcpiS3Enable, and
doesn't have any control over QEMU, so QEMU would probably always say S3
is available.

What happen when "acpi_s3" is set or not is:
    - the value is stored in xenstore
    - hvmloader (which runs before OVMF) read the xenstore value and
      adds the appropriate ACPI SSDT table to allow S3.

Cheers,

-- 
Anthony PERARD

      reply	other threads:[~2021-07-27 10:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-08  4:05 [RFC PATCH] OvmfPkg/OvmfXen: set PcdAcpiS3Enable at initialization Gary Lin
2021-07-19  7:34 ` Ard Biesheuvel
2021-07-19 10:11 ` Anthony PERARD
2021-07-19 16:07 ` Anthony PERARD
2021-07-19 16:48   ` Ard Biesheuvel
2021-07-20  6:52   ` Gary Lin
     [not found]   ` <16936D3065173CA9.5055@groups.io>
2021-07-21  6:56     ` [edk2-devel] " Gary Lin
2021-07-27 10:57       ` Anthony PERARD [this message]

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