Subject: Re: [PATCH 1/7] KVM: userspace interface
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Anthony Liguori <aliguori@us.ibm.com>
Cc: John Stoffel <john@stoffel.org>, Avi Kivity <avi@qumranet.com>,
       linux-kernel <linux-kernel@vger.kernel.org>
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Date: Thu, 19 Oct 2006 21:36:40 +0100
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Ar Iau, 2006-10-19 am 13:49 -0500, ysgrifennodd Anthony Liguori:
> ioctls are probably wrong here though.  Ideally, you would want to be 
> able to support an SMP guest.  This means you need to have two virtual 
> processors executing in kernel space.  If you use ioctls, it forces you 

Not really and in fact with qemu you'd want to halt a trap on the second
virtual CPU until emulation was over if only to get I/O and other
instruction ordering right. Thats not an argument that only that view
should be supported of course.

> If you used a read/write interface, you could poll for any number of 
> processors and handle IO emulation in a single userspace thread (which 
> seems closer to how hardware really works anyway).

Agreed.

Alan

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