From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MsfOG-0005TX-39 for qemu-devel@nongnu.org; Tue, 29 Sep 2009 12:17:24 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MsfOB-0005QU-DT for qemu-devel@nongnu.org; Tue, 29 Sep 2009 12:17:23 -0400 Received: from [199.232.76.173] (port=34012 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MsfOB-0005QQ-8Q for qemu-devel@nongnu.org; Tue, 29 Sep 2009 12:17:19 -0400 Received: from mx20.gnu.org ([199.232.41.8]:35945) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MsfOA-000140-JV for qemu-devel@nongnu.org; Tue, 29 Sep 2009 12:17:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]) by mx20.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MsdNH-0003pi-J5 for qemu-devel@nongnu.org; Tue, 29 Sep 2009 10:08:15 -0400 Date: Tue, 29 Sep 2009 16:06:02 +0200 From: "Michael S. Tsirkin" Message-ID: <20090929140601.GA28733@redhat.com> References: <4AB8DD53.7070806@redhat.com> <4AB8DECA.3090908@redhat.com> <4AB8E88C.4040103@redhat.com> <4AB980E6.2070203@codemonkey.ws> <4AB9AA8E.7060800@third-harmonic.com> <4AC1A49A.1010308@redhat.com> <20090929065856.GC25389@redhat.com> <4AC1B5CD.7050702@redhat.com> <20090929085450.GE25389@redhat.com> <4AC211C8.1060202@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AC211C8.1060202@codemonkey.ws> Subject: [Qemu-devel] Re: [PATCH 0/2] fix virtio_blk serial pci config breakage List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: john cooper , john cooper , Rusty Russell , qemu-devel@nongnu.org, Avi Kivity , jens.axboe@oracle.com, Vadim Rozenfeld On Tue, Sep 29, 2009 at 08:55:20AM -0500, Anthony Liguori wrote: > Michael S. Tsirkin wrote: >> On Tue, Sep 29, 2009 at 09:22:53AM +0200, Avi Kivity wrote: >> >>> On 09/29/2009 08:58 AM, Michael S. Tsirkin wrote: >>> >>>> Using bar per feature we'll quickly run out of BARs. >>>> We already use a BAR for MSI-X - let's add >>>> ATA identity there? >>>> >>> Mixing unrelated features will quickly cause confusion. >>> >> >> Note if we ever switch to 64 bit BARs, we'll only have 3 of these >> available, so the ID would be using the last free one. >> We can just as well plan ahead for when we'll add another feature? >> >> I agree fixed offsets are messy though. I previously proposed storing >> the offset to the identity data in an i/o register. This will let each >> implementation lay out this data in an optimal manner, without >> confusion. >> > > 1) There's no need to make the identity page separate from the config > space. The real problem is the config space is too small. We can fix > that without making any changes to virtio-blk by putting the config > space in a separate BAR. I don't think it's such a good idea. We want to keep exposing most of config space in i/o bar because of backwards compatibility. And we want to keep datapath operations such as vq kicks, in i/o space. > 2) Passing an ATA identity page is goofy. We should just pass the > serial number and let Linux generate the identity page. Just because > Linux requires this as it's user space interface, that doesn't mean that > other guests will (like Windows). Instead of exposing an opaque blob, > we should expose the information we need in a structured way. > > Regards, > > Anthony Liguori