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Date: Sun, 25 Aug 2013 08:44:00 +0200
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Subject: Re: [Qemu-devel] [PATCH 2/2] hpet: inverse polarity when pin above
	ISA_NUM_IRQS
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To: Liu Ping Fan <qemulist@gmail.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>

Il 25/08/2013 04:16, Liu Ping Fan ha scritto:
> According to hpet spec, hpet irq is high active. But according to
> ICH spec, there is inversion before the input of ioapic. So the OS
> will expect low active on this IRQ line.(And this is observed on
> bare metal).
> 
> We fold the emulation of this inversion inside the hpet logic.
> 
> Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> ---
> kernel has a bug with ioapic, refer to
>    https://lkml.org/lkml/2013/8/23/98
> With all these patch, linux-2.6/Documentation/timers/hpet_example.c can work
> on qemu 

Can you explain "in qemu q35 machine ioapic's ioredtbl[x] can never be
set as low-active, even if the hpet driver registered it"?

Paolo