From: Ingo Molnar <mingo@elte.hu>
To: Gleb Natapov <gleb@redhat.com>
Cc: linux-kernel@vger.kernel.org, yinghai@kernel.org,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] decouple x2apic from irq remapping
Date: Thu, 19 Feb 2009 12:30:18 +0100 [thread overview]
Message-ID: <20090219113018.GS2354@elte.hu> (raw)
In-Reply-To: <20090218120051.GF26845@redhat.com>
* Gleb Natapov <gleb@redhat.com> wrote:
> Hi,
>
> Currently x2apic is used only if interrupt remapping can be enabled,
> but if all apic ids are smaller then 255 there is no reason to
> enable interrupt remapping at all. Although there is not real HW that has
> x2apic but does not have IR the decoupling is useful since we want to
> emulate x2apic interface in KVM (it is more vitalization friendly), but
> we don't want to emulate IR just for that.
>
> According to Intel docs BIOS should pass control to OS in x2apic mode
> if there are apics with id > 255 and in xapic otherwise, so the proposed
> patch requires IR configuration only if BIOS switched apic to x2apic
> mode.
>
> The patch is against tip:x86/apic.
Applied to tip:x86/apic, thanks Gleb!
Ingo
prev parent reply other threads:[~2009-02-19 11:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-18 12:00 [PATCH] decouple x2apic from irq remapping Gleb Natapov
2009-02-19 11:30 ` Ingo Molnar [this message]
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