From: Anthony Liguori <anthony@codemonkey.ws>
To: Cam Macdonell <cam@cs.ualberta.ca>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
qemu-devel@nongnu.org, Alexander Graf <agraf@suse.de>
Subject: Re: [Qemu-devel] [PATCH] VirtIO Support for Memory Regions
Date: Wed, 24 Feb 2010 09:41:17 -0600 [thread overview]
Message-ID: <4B85489D.60607@codemonkey.ws> (raw)
In-Reply-To: <4B85420A.6090903@codemonkey.ws>
On 02/24/2010 09:13 AM, Anthony Liguori wrote:
>> to work on that if we can agree on what the underlying device looks
>> like whether it should be VirtIO or just PCI.
> Agreed, you had suggested uio_pci for my PCI driver and I'd be happy
>
> I feel pretty strongly that we shouldn't add shared memory to virtio.
> I'm pretty sure Christian would too because it eliminates the
> possibility of implementing a copy-based transport for virtio
> (virtio-over-ethernet).
Actually, ignore my crazy justification based on virtio-over-ethernet :-)
Certain hypervisors (like Xen and PHYP) have very limited/non-existent
support for shared memory. In the case of Xen, there's a very small
pool that can be used for DMA buffers. In the case of PHYP, you have
hardware accelerated copying for all I/O.
Adding shared memory to virtio means that virtio could not be supported
(or at least, all virtio devices) on these hypervisors.
Regards,
Anthony Liguori
prev parent reply other threads:[~2010-02-24 15:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-23 20:52 [Qemu-devel] [PATCH] VirtIO Support for Memory Regions Cam Macdonell
2010-02-23 21:05 ` Anthony Liguori
2010-02-23 21:09 ` Anthony Liguori
2010-02-24 6:20 ` Cam Macdonell
2010-02-24 11:14 ` Avi Kivity
2010-02-24 15:01 ` Anthony Liguori
2010-02-24 15:13 ` Anthony Liguori
2010-02-24 15:41 ` Anthony Liguori [this message]
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