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[Xen-devel] bogus HPET initialization order on x86

To: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] bogus HPET initialization order on x86
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Wed, 09 Mar 2011 14:45:01 +0000
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>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.

Thanks, Jan


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