Re: [Xen-devel] [PATCH 02/18] xen/arm: Implement PSCI system suspend call (virtual interface)

[Julien Grall <julien.grall@xxxxxxx>]

On 13/11/2018 20:39, Stefano Stabellini wrote:
> On Tue, 13 Nov 2018, Julien Grall wrote:
>
> If we mark the domU simply as "paused" it will be difficult to implement
> correctly "xl restore" / "xl trigger s3resume". We should be able to
> distinguish a domain which is simply not running or paused (as in "xl
> pause") from one that has been put to sleep.  Otherwise we won't be able
> to use "xl pause" in its original sense anymore. "xl pause" will become
> effectively "xl trigger sleep" on ARM. Which is something to consider
> but I don't think that is what we want.
I didn't suggested to only use those 2 helpers. But you can build suspend/resume 
on top of it. AFAICT, this is how s3 suspend/resume works on x86 HVM.
> The most similar feature is ACPI S3 in x86-land but the current calls
> are so ACPI/x86 specific that don't make much sense on a ACPI-less ARM
> implementation. If I am not mistaken, on x86 there is a special struct
> domain flag for this: d->arch.hvm.is_s3_suspended.
>
>
> Let's leave aside the "which commands should we use" discussion for now
> because it doesn't related to this patch series. It seems to me that the
> best option is to introduce a new ARM specific struct domain flag,
> something akin to d->arch.hvm.is_s3_suspended but ARM PSCI specific.
See above.

--
Julien Grall

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