From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:51663) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLaPu-0006We-MQ for qemu-devel@nongnu.org; Tue, 09 Oct 2012 10:04:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TLaPl-0002NL-6A for qemu-devel@nongnu.org; Tue, 09 Oct 2012 10:04:14 -0400 Received: from e23smtp08.au.ibm.com ([202.81.31.141]:54739) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLaPk-0002MZ-Ki for qemu-devel@nongnu.org; Tue, 09 Oct 2012 10:04:05 -0400 Received: from /spool/local by e23smtp08.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 10 Oct 2012 00:03:10 +1000 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q99Ds9Y043384904 for ; Wed, 10 Oct 2012 00:54:09 +1100 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q99E3mpj002176 for ; Wed, 10 Oct 2012 01:03:49 +1100 From: Anthony Liguori In-Reply-To: <5073F9D4.5060000@redhat.com> 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> Date: Tue, 09 Oct 2012 09:03:40 -0500 Message-ID: <87y5jfwxmr.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: Re: [Qemu-devel] Using PCI config space to indicate config location List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity , Rusty Russell Cc: qemu-devel , virtualization@lists.linux-foundation.org, Gerd Hoffmann , kvm@vger.kernel.org, "Michael S. Tsirkin" 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