From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH 12/22] virtio_pci: allow duplicate capabilities.
Date: Thu, 21 Mar 2013 19:49:12 +0200
Message-ID: <20130321174912.GA4161@redhat.com>
References: <514B26BC.6010700@zytor.com> <20130321155810.GA1925@redhat.com>
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	<514B3EAE.8000707@zytor.com> <20130321171319.GD2994@redhat.com>
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To: "H. Peter Anvin" <hpa@zytor.com>
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On Thu, Mar 21, 2013 at 07:13:19PM +0200, Michael S. Tsirkin wrote:
> On Thu, Mar 21, 2013 at 10:09:02AM -0700, H. Peter Anvin wrote:
> > On 03/21/2013 10:07 AM, Michael S. Tsirkin wrote:
> > > 
> > > I just think it does not apply to BIOS so much.  A bigger issue for BIOS
> > > virtio performance is that it normally does not implement batching at
> > > all, to keep it simple and reduce memory usage it uses a small number
> > > (often 1) of outstanding buffers per queue.
> > > 
> > 
> > You asked for examples, so I gave one.  There is no doubt that BIOS can
> > make use of this if available.
> > 
> > What you describe above is of course a typical problem with BIOS.
> > 
> > 	-hpa
> 
> Right, thanks.
> Also thanks for the spec quote, I really think we should add the config
> cycle access as a guaranteed feature.  It's easy and I expect all BIOS
> drivers to use it.

Just to clarify, I expect BIOS to use it *for config access*.
Notification will support IO anyway because it's
faster on KVM, so BIOS can use it directly.

> -- 
> MST