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Mon, 13 Jan 2020 16:17:48 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id D089A1138600; Mon, 13 Jan 2020 17:17:46 +0100 (CET) From: Markus Armbruster To: Paolo Bonzini Subject: Re: Priority of -accel References: <20200106130951.29873-1-philmd@redhat.com> <12334054-4ae7-e580-9727-2d322bfa2bda@redhat.com> <1A5859EA-4403-4921-B527-DFD07C59C702@redhat.com> <360fa010-ba80-b02b-3a35-19c2b48a462d@redhat.com> Date: Mon, 13 Jan 2020 17:17:46 +0100 In-Reply-To: <360fa010-ba80-b02b-3a35-19c2b48a462d@redhat.com> (Paolo Bonzini's message of "Tue, 7 Jan 2020 15:37:35 +0100") Message-ID: <87d0bnwct1.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: bNZGqzEjMK-gMtCh4TdeWQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Thomas Huth , Daniel Berrange , qemu-block@nongnu.org, qemu-devel@nongnu.org, Wainer dos Santos Moschetta , Max Reitz , Christophe de Dinechin , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Paolo Bonzini writes: > On 07/01/20 14:55, Christophe de Dinechin wrote: >> So what about ranking the accelerators, so that all combinaisons >> -accel=3Dkvm:tcg, -accel=3Dtcg:kvm, -accel kvm -accel tcg, etc would > > (I assume you mean "-machine accel=3Dkvm:tcg" and "-machine accel=3Dtcg:k= vm" > for the first two. This is the "older" way which has now become sugar > for "-accel kvm -accel tcg"). > >> all pickup kvm if available, and tcg as a fallback? Implementation-wise, >> it would simply mean ranking the accelerators and updating the accelerat= or >> only if it=E2=80=99s available and better. > > This is an interesting idea. I like this better than "-accel best", > because "-accel best" has the problem that you can't add suboptions to > it (the suboptions for the various accelerators are disjoint). > > It would break backwards compatibility for "-machine accel=3Dtcg:kvm", > which so far meant "use TCG if compiled in, otherwise use KVM". This is > not something I would have a problem with... except that "tcg:kvm" is > the default if no -accel option is provided! Perfect opportunity to change the default to something more useful.