Re: [Xen-devel] Clock interrupts + hypervisor calls

To:	"Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject:	Re: [Xen-devel] Clock interrupts + hypervisor calls
From:	"sowmya dayanand" <sowmyad@xxxxxxxxx>
Date:	Tue, 28 Feb 2006 12:22:05 -0700
Cc:	Xen-devel@xxxxxxxxxxxxxxxxxxx
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Is there a flag that the long-lived hypercalls set to indicate that they can be preempted? Also is the flag per-domain to indicate that the hypercall is in progress in the particular domain?

Thanks,

Sowmya.

On 2/21/06, Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> wrote:

On 21 Feb 2006, at 07:39, sowmya dayanand wrote:

> Hi All,
>
> I wanted to know if a clock interrupt from any of the guest OS
> interrupt/preempt a hypervisor call in xen?
>
> Eg: say the disk access hy per call is in progress and a guest OS on
> another domain generates a clock interrupt, can this interrupt be
> handled in the middle of the hypervisor call or does it have to wait?

There is no disc access hypercall as Xen does not do I/O itself.
Long-lived hypercalls can be voluntarily preempted by events. The
hypercall is resumed without the guest needing to do anything special.

-- Keir

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