RE: [Xen-devel] [PATCH 0/4] HVM Virtual S3

["Yu, Ke" <ke.yu@xxxxxxxxx>]

Keir Fraser  wrote on 6:34:
> On 16/5/07 22:59, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:
> 
>>> The main idea is:
>>> - emulate ACPI PM1A control resiger in QEMU to capture guest S3
>>> request 
>>> - when QEMU capture guest S3 request, it call hypercall to trap to
>>> Xen 
>> 
>> So why emulate this register in QEMU at all, rather than directly in
>> Xen? Xen already knows the address of the pm1a block of ports
>> because it emulates the pmtimer.
> 
> Oh, I see there is device state to be reset in QEMU. Emulating the
> port access in QEMU makes sense then, but I wonder if rather than
> adding an extra hypercall command we could emulate it in both Xen and
> QEMU: Xen emulates the instruction, resets state and triggers domain
> shutdown, then passes the port access up to QEMU so it does its thing
> also. We do this emulate-in-both for other things already (e.g., the
> CMOS index register I believe). 
> 
>  -- Keir

Yes. that's a good idea. The only disadvantage is that it scatter the
ACPI register logic from QEMU, and make it a little bit harder for
maintaince. But it is a acceptable tradeoff. 

Best Regards
Ke

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