From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [Qemu-devel] Using PCI config space to indicate config location Date: Tue, 09 Oct 2012 09:03:40 -0500 Message-ID: <87y5jfwxmr.fsf@codemonkey.ws> References: <87zk4c2tqq.fsf@rustcorp.com.au> <874nmajcmj.fsf@codemonkey.ws> <87y5jhpuu2.fsf@rustcorp.com.au> <87bogddq0l.fsf@codemonkey.ws> <5072EA14.30809@redhat.com> <87k3v1gfw1.fsf@codemonkey.ws> <507333F1.1060000@redhat.com> <874nm4u1in.fsf@codemonkey.ws> <87sj9o8qn7.fsf@rustcorp.com.au> <87sj9oh0pm.fsf@codemonkey.ws> <87haq48hds.fsf@rustcorp.com.au> <5073F9D4.5060000@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5073F9D4.5060000@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Avi Kivity , Rusty Russell Cc: qemu-devel , virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, "Michael S. Tsirkin" List-Id: virtualization@lists.linuxfoundation.org Avi Kivity writes: > On 10/09/2012 05:16 AM, Rusty Russell wrote: >> Anthony Liguori writes: >>> We'll never remove legacy so we shouldn't plan on it. There are >>> literally hundreds of thousands of VMs out there with the current virtio >>> drivers installed in them. We'll be supporting them for a very, very >>> long time :-) >> >> You will be supporting this for qemu on x86, sure. As I think we're >> still in the growth phase for virtio, I prioritize future spec >> cleanliness pretty high. > > If a pure ppc hypervisor was on the table, this might have been > worthwhile. As it is the codebase is shared, and the Linux drivers are > shared, so cleaning up the spec doesn't help the code. Note that distros have been (perhaps unknowingly) shipping virtio-pci for PPC for some time now. So even though there wasn't a hypervisor that supported virtio-pci, the guests already support it and are out there in the wild. There's a lot of value in maintaining "legacy" support even for PPC. >> But I think you'll be surprised how fast this is deprecated: >> 1) Bigger queues for block devices (guest-specified ringsize) >> 2) Smaller rings for openbios (guest-specified alignment) >> 3) All-mmio mode (powerpc) >> 4) Whatever network features get numbers > 31. >> >>> I don't think we gain a lot by moving the ISR into a separate BAR. >>> Splitting up registers like that seems weird to me too. >> >> Confused. I proposed the same split as you have, just ISR by itself. > > I believe Anthony objects to having the ISR by itself. What is the > motivation for that? Right, BARs are a precious resource not to be spent lightly. Having an entire BAR dedicated to a 1-byte register seems like a waste to me. Regards, Anthony Liguori > > > -- > error compiling committee.c: too many arguments to function > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html