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From: Glauber Costa <glommer@redhat.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 0/6] in kernel irqchip support
Date: Mon, 28 Sep 2009 22:06:15 -0300	[thread overview]
Message-ID: <20090929010614.GS29735@mothafucka.localdomain> (raw)
In-Reply-To: <20090929003958.GA5527@shareable.org>

On Tue, Sep 29, 2009 at 01:39:58AM +0100, Jamie Lokier wrote:
> Glauber Costa wrote:
> >I am ready to advocate that it should be the default, whenever
> >available.  I plan to, however, provide a patch that disables it
> >whenever this gets merged.
> 
> Is the in-kernel irqchip simply intended to accelerate some part of
> the CPU/irq emulation, so that you could enable or disable it at will,
> as well as migrating to TCG-using systems and back, with no observable
> effect except performance?
I don't think we can migrate between kvm and tcg. Although it should be possible
in theory, since we just load the state, there are some differences, specially
with respect to memory layout between kvm and pure tcg. i.e., IIRC, kvm puts two
extra pages in the end of the registered physical memory. Although it can be possible,
I don't think anyone has enough interest to make it happen.

As for in-kernel chip, to be honest, I have never tried migrating between two system,
one having it, and one lacking it. But I believe it should be possible, and this
is a much easier goal to accomplish.

  reply	other threads:[~2009-09-29  1:06 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-28 21:15 [Qemu-devel] [PATCH 0/6] in kernel irqchip support Glauber Costa
2009-09-28 21:15 ` [Qemu-devel] [PATCH 1/6] provide in-kernel ioapic Glauber Costa
2009-09-28 21:15   ` [Qemu-devel] [PATCH 2/6] provide in-kernel apic Glauber Costa
2009-09-28 21:15     ` [Qemu-devel] [PATCH 3/6] provide apic_set_irq_delivered Glauber Costa
2009-09-28 21:15       ` [Qemu-devel] [PATCH 4/6] provide in-kernel i8259 chip Glauber Costa
2009-09-28 21:15         ` [Qemu-devel] [PATCH 5/6] initialize " Glauber Costa
2009-09-28 21:15           ` [Qemu-devel] [PATCH 6/6] Initialize in-kernel irqchip Glauber Costa
2009-10-02 20:33             ` [Qemu-devel] " Jan Kiszka
2009-10-02 21:59               ` Jamie Lokier
2009-10-02 22:22                 ` Glauber Costa
2009-09-28 22:04         ` [Qemu-devel] Re: [PATCH 4/6] provide in-kernel i8259 chip Juan Quintela
2009-09-28 22:25           ` Glauber Costa
2009-09-28 22:39             ` Juan Quintela
2009-10-02 20:33               ` Jan Kiszka
     [not found]   ` <m3my4eagcp.fsf@neno.mitica>
2009-09-28 22:24     ` [Qemu-devel] Re: [PATCH 1/6] provide in-kernel ioapic Glauber Costa
2009-09-29  0:39 ` [Qemu-devel] [PATCH 0/6] in kernel irqchip support Jamie Lokier
2009-09-29  1:06   ` Glauber Costa [this message]
2009-09-29  8:15 ` Avi Kivity
2009-09-30 20:01 ` Anthony Liguori

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