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Re: [XEN PATCH] x86/hvm: make ACPI PM timer support optional

To: Stefano Stabellini <sstabellini@xxxxxxxxxx>

From: Sergiy Kibrik <sergiy_kibrik@xxxxxxxx>

Date: Wed, 18 Sep 2024 12:29:39 +0300

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Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx, Jan Beulich <jbeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>

Delivery-date: Wed, 18 Sep 2024 09:29:53 +0000

List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

16.09.24 22:57, Stefano Stabellini:

On Mon, 16 Sep 2024, Roger Pau Monné wrote:

On Mon, Sep 16, 2024 at 09:37:57AM +0300, Sergiy Kibrik wrote:

Introduce config option X86_PMTIMER so that pmtimer driver can be disabled on
systems that don't need it.


Same comment as in the VGA patch, you need to handle the user passing
X86_EMU_PM.  It's not OK to just ignore the flag if the hypervisor is
built without ACPI PM timer support.


I also think that the flag should not be ignored. I think that Xen
should return error if a user is passing a domain feature not supported
by a particular version of the Xen build. I don't think that libxl needs
to be changed as part of this patch necessarily.

It looks like toolstack always leaves X86_EMU_PM bit enabled, so that

part may also require changes.

-Sergiy

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