From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [PATCH 16/22] virtio_pci: use separate notification offsets for each vq. Date: Wed, 27 Mar 2013 10:37:20 +1030 Message-ID: <87ip4d4sef.fsf@rustcorp.com.au> References: <1363854584-25795-1-git-send-email-rusty@rustcorp.com.au> <1363854584-25795-17-git-send-email-rusty@rustcorp.com.au> <20130321101300.GA30493@redhat.com> <87wqt0du2e.fsf@rustcorp.com.au> <20130324201910.GA31631@redhat.com> <8738vjer43.fsf@rustcorp.com.au> <20130326193911.GA19251@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130326193911.GA19251@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: "Michael S. Tsirkin" Cc: hpa@zytor.com, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org "Michael S. Tsirkin" writes: > On Mon, Mar 25, 2013 at 08:30:28PM +1030, Rusty Russell wrote: >> Let's go back a level. Do we still need I/O bars at all now? Or can we >> say "if you want hundreds of vqs, use mem bars"? >> >> hpa wanted the option to have either, but do we still want that? > > hpa says having both is required for BIOS, not just for speed with KVM. OK so the offset must not be applied to the I/O bar as you suggested. Since AFAICT I/O bars are deprecated, should we insist that there be a memory bar, and the I/O bar is optional? Or just leave it entirely undefined, and say there can be either or both? I dislike the idea of BIOS code which assumed an I/O bar and thus won't work with a compliant device which doesn't provide one. I'd prefer all compliant drivers to work with all compliant devices. Cheers, Rusty.