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Date: Fri, 18 May 2007 11:28:25 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Subject: Re: [patch] x86_64, irq: check remote IRR bit before migrating level triggered irq
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, mingo@elte.hu, ak@suse.de,
       akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
       "Zou, Nanhai" <nanhai.zou@intel.com>,
       "Mallick, Asit K" <asit.k.mallick@intel.com>,
       "Packard, Keith" <keith.packard@intel.com>
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References: <20070518010119.GB12088@linux-os.sc.intel.com>
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On 5/18/07, Siddha, Suresh B <suresh.b.siddha@intel.com> wrote:
>
> If the vector number stays same during irq migration and if we reset remote
> IRR bit using the above method(edge and then back to level) during
> irq migration, then we have a problem. A new interrupt arriving on a new
> cpu will set the remote IRR bit and now the old inflight EOI broadcast
> reaches IOAPIC RTE(resetting the remote IRR bit, because the vector in the
> broadcast msg is same), while the kernel code still assumes that the remote
> IRR bit is still set. This will lead to more problems and issues.

coud add some line __assign_irq_vector. to make sure old_vector!=vector.

YH