Re: [Xen-devel] Local APIC doesn't implement "One shot" mode?

[Keir Fraser <keir@xxxxxxx>]

On 23/11/2010 14:00, "alarson@xxxxxxxx" <alarson@xxxxxxxx> wrote:

> I've now have gotten our OS running on Xen 4.0.  Many thanks.
> 
> However it appears that the Local APIC presented to the client only
> implements the "periodic" timer mode, and not "one shot" (bit 17 of the
> APIC Local Vector Table).  I say "apparently" because I have limited time
> on the hardware so I didn't have time to write a definitive test case, but
> the external visible behavior is that the local apic timer does not stop
> at zero when programmed for "one-shot" mode.  This isn't overly difficult
> for me to work around, but I thought I'd mention it just in case it
> warranted fixing.  If desired, I can confirm my conjecture the next time I
> have time on the hardware.

You are correct in your observation. If you care about correct one-shot
behaviour for reads of the current-count register, I can propose a patch for
you to test?

 -- Keir

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