Subject: Re: QEMU PIC indirection patch for in-kernel APIC work

From: Rusty Russell <rusty-8n+1lVoiYb80n/[email-masked]>
Date: Mon, 09 Apr 2007 12:50:18 +1000

On Sun, 2007-04-08 at 08:36 +0300, Avi Kivity wrote:
> Rusty Russell wrote:
> > Hi Avi,
> >
> > 	I don't think you've thought about this very hard.  The receive copy is
> > completely independent with whether the packet is going to the guest via
> > a kernel driver or via userspace, so not relevant.
> >   
> 
> A packet received in the kernel cannot be made available to userspace in 
> a safe manner without a copy, as it will not be aligned with page 
> boundaries, so userspace cannot examine the packet until after one copy 
> has occured.

Hi Avi!

	I'm a little puzzled by your response.  Hmm...

	lguest's userspace network frontend does exactly as many copies as
Ingo's in-host-kernel code.  One from the Guest, one to the Guest.

Does that clarify?
Rusty.

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