Re: [Xen-devel] suspending execution within Xen

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

Xen on x86 doesn't support stack-based continuations within the 
hypervisor -- that is, there is no way to deschedule the current domain 
within Xen and then automatically return to your current point of 
execution when you are re-scheduled.
If you have further work to do, before returning to guest context, when 
the domain is rescheduled then you need to install your own hook 
function into vcpu->arch.schedule_tail. You'll need to xmalloc any 
space you need for continuation data.
 -- Keir

On 29 Jun 2005, at 12:53, Avi Kivity wrote:

> I am trying to send a stream of events about one domain to another. so 
> I
> set up a ring between the monitoring domain and xen (not the monitored
> domain). however I am having trouble blocking when buffer space runs
> out.
>
> the intuitive
>
>    while (!buffer_space_available())
>        do_block();
>
> does not work; do_block() appears to return to guest context, not to 
> the
> while loop (is this correct?). the other alternative,
>
>     while (!buffer_space_available())
>         if (!test_and_set_bit(EDF_BLOCKED, &ed->ed_flags))
>             domain_sleep(ed);
>
> freezes xen solid.
>
> is there a way to do it? am I missing something obvious?
>
> Avi
>
>
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