From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40162) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHCFA-0006zw-3h for qemu-devel@nongnu.org; Fri, 30 Jan 2015 09:08:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YHCF6-00031E-QC for qemu-devel@nongnu.org; Fri, 30 Jan 2015 09:08:20 -0500 Received: from e06smtp16.uk.ibm.com ([195.75.94.112]:57883) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHCF6-00030u-HA for qemu-devel@nongnu.org; Fri, 30 Jan 2015 09:08:16 -0500 Received: from /spool/local by e06smtp16.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 30 Jan 2015 14:08:13 -0000 Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id E69A92190066 for ; Fri, 30 Jan 2015 14:08:07 +0000 (GMT) Received: from d06av05.portsmouth.uk.ibm.com (d06av05.portsmouth.uk.ibm.com [9.149.37.229]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t0UE8AkU47120412 for ; Fri, 30 Jan 2015 14:08:10 GMT Received: from d06av05.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av05.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t0UE8AZ2006538 for ; Fri, 30 Jan 2015 07:08:10 -0700 Date: Fri, 30 Jan 2015 15:08:08 +0100 From: Cornelia Huck Message-ID: <20150130150808.007c6572.cornelia.huck@de.ibm.com> In-Reply-To: <20150107191006.GB8734@redhat.com> References: <1418304322-7546-1-git-send-email-cornelia.huck@de.ibm.com> <1418304322-7546-19-git-send-email-cornelia.huck@de.ibm.com> <20141228083206.GA6802@redhat.com> <20150107172232.57cbeb31.cornelia.huck@de.ibm.com> <20150107191006.GB8734@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH RFC v6 18/20] virtio: support revision-specific features List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: thuth@linux.vnet.ibm.com, rusty@rustcorp.com.au, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org On Wed, 7 Jan 2015 21:10:07 +0200 "Michael S. Tsirkin" wrote: > On Wed, Jan 07, 2015 at 05:22:32PM +0100, Cornelia Huck wrote: > > On Sun, 28 Dec 2014 10:32:06 +0200 > > "Michael S. Tsirkin" wrote: > > > > > On Thu, Dec 11, 2014 at 02:25:20PM +0100, Cornelia Huck wrote: > > > > Devices may support different sets of feature bits depending on which > > > > revision they're operating at. Let's give the transport a way to > > > > re-query the device about its features when the revision has been > > > > changed. > > > > > > > > Signed-off-by: Cornelia Huck > > > > > > So now we have both get_features and get_features_rev, and > > > it's never clear which revision does host_features refer to. > > > IMHO that's just too messy. > > > Let's add get_legacy_features and host_legacy_features instead? > > > > I wanted to avoid touching anything that does not support version 1. > > And this interface might still work for later revisions, no? > > We can add _modern_ then, or rename host_features to host_legacy_features > everywhere as preparation. > OK, I've ditched the "don't modify old stuff" goal and introduced ->get_features_legacy(). For now, devices will add VERSION_1 in their ->get_features() callback when they support it. (For many devices, this will be the only difference between the two callbacks.) Two sets of host_features don't make much sense to me. I've hacked up something and will play with it a bit; I might post a new patch series next week.