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Re: [Xen-devel] bogus HPET initialization order on x86


  • To: Jan Beulich <JBeulich@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <keir.xen@xxxxxxxxx>
  • Date: Wed, 09 Mar 2011 16:12:02 +0000
  • Cc: ke.yu@xxxxxxxxx
  • Delivery-date: Wed, 09 Mar 2011 08:12:44 -0800
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  • Thread-topic: [Xen-devel] bogus HPET initialization order on x86

On 09/03/2011 14:45, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

>> From looking at the code I cannot deduce why it wouldn't be possible
> for hpet_interrupt_handler() or hpet_legacy_irq_tick() to be called
> while hpet_broadcast_init() is still executing. If that's indeed possible,
> then the setting of .event_handler clearly has to happen *after*
> initializing the channel's spinlock and rwlock.
> 
> Further, with the channel getting enabled (down the
> hpet_fsb_cap_lookup() call tree) before hpet_events[] gets fully
> initialized, I'd also think it should be possible to hit the spurious
> warning in hpet_interrupt_handler() just because of improper
> initialization order.
> 
> If that's all impossible in practice, adding some meaningful
> comments to the code to describe why this is so would be much
> appreciated.

Only someone at Intel could answer these questions. Cc'ing Yu Ke, who seems
most involved in this aspect.

 -- Keir

> Thanks, Jan
> 
> 
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