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[Xen-devel] Re: [PATCH] C6 state with EOI issue fix for some Intel proce

To: Sheng Yang <sheng@xxxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] C6 state with EOI issue fix for some Intel processors
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Wed, 15 Sep 2010 08:32:26 +0100
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Thread-topic: [PATCH] C6 state with EOI issue fix for some Intel processors
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Aieee! :-)


On 15/09/2010 08:10, "Sheng Yang" <sheng@xxxxxxxxxxxxxxx> wrote:

> There is an errata in some of Intel processors.
> AAJ72. EOI Transaction May Not be Sent if Software Enters Core C6 During
> an Interrupt Service Routine
> If core C6 is entered after the start of an interrupt service routine but
> before
> a write to the APIC EOI register, the core may not send an EOI transaction (if
> needed) and further interrupts from the same priority level or lower may be
> blocked.
> This patch fix this issue, by checking if ISR is pending before enter deep Cx
> state. If so, it would use power->safe_state instead of deep Cx state to
> prevent 
> the above issue happen.

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