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[83.42.66.34]) by smtp.gmail.com with ESMTPSA id x17sm76359879wrt.74.2020.01.07.04.34.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Jan 2020 04:34:24 -0800 (PST) Subject: Re: Priority of -accel To: Thomas Huth , Paolo Bonzini References: <20200106130951.29873-1-philmd@redhat.com> <12334054-4ae7-e580-9727-2d322bfa2bda@redhat.com> <58eb34db-7d32-8b0e-d9ef-98648209486b@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <7322b7c9-51a9-f8e3-9d90-1d242d1c8cb4@redhat.com> Date: Tue, 7 Jan 2020 13:34:23 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <58eb34db-7d32-8b0e-d9ef-98648209486b@redhat.com> Content-Language: en-US X-MC-Unique: pX4fZQUCP0-G7OCIEljVOw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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 , "Daniel P. Berrange" , qemu-block@nongnu.org, Markus Armbruster , qemu-devel@nongnu.org, Wainer dos Santos Moschetta , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 1/7/20 1:18 PM, Thomas Huth wrote: > On 07/01/2020 11.14, Paolo Bonzini wrote: >> On 07/01/20 11:03, Thomas Huth wrote: >>>> >>>> vm = QEMUMachine(iotests.qemu_prog) >>>> -vm.add_args('-machine', 'accel=kvm:tcg') >>>> +vm.add_args('-accel', 'kvm', '-accel', 'tcg') >>> Looking at this, I wonder whether we really want the "-accel" option to >>> prioritize the accelerators in the order of appearance? A lot of other >>> CLI tools give the highest priority to the last parameter instead, e.g. >>> "gcc -O3 -O1" compiles with -O1, and not with -O3. >>> >>> Also I think it might be quite common that there are shell scripts which >>> call "qemu-system-xxx -accel xyz $*" ... and if we don't invert the >>> priorities of -accel, it will be impossible to override -accel in that >>> case... >> >> Hmm, it does match "-machine accel=kvm:tcg" and in general I think it's >> more self-explanatory. However, it is indeed less friendly to scripts. >> On one hand those could be changed to place "-accel xyz" after $* (or >> better "$@"), on the other hand we could also add a priority option to >> "-accel". What do you think? > > I don't think we need a separate priority parameter here. But IMHO it's > really rather common practice to prioritize the last option. So while > it might be more "self-explanatory" to a CLI newbie if the first > occurrence got the highest priority, it might be rather confusing > instead for a CLI veteran...? > > What do others on the list here think about this? We can make CLI more complex by adding a 'priority' option: -accel tcg,priority=1 -accel kvm,priority=0