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[109.66.7.121]) by smtp.gmail.com with ESMTPSA id c20sm6711698wmd.36.2020.04.28.23.52.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Apr 2020 23:52:56 -0700 (PDT) Date: Wed, 29 Apr 2020 02:52:54 -0400 From: "Michael S. Tsirkin" To: Ani Sinha Subject: Re: [PATCH V2] Add a new PIIX option to control PCI hot unplugging of devices on non-root buses Message-ID: <20200429025200-mutt-send-email-mst@kernel.org> References: <1588069012-211196-1-git-send-email-ani.sinha@nutanix.com> <20200428120426-mutt-send-email-mst@kernel.org> <67e481a5-de04-4e01-b9ec-70932194d69f@Spark> <20200428121837-mutt-send-email-mst@kernel.org> <20200428164428-mutt-send-email-mst@kernel.org> <20200429011228-mutt-send-email-mst@kernel.org> <544B4749-9A1C-44BB-BD89-C37A7E8D86F4@nutanix.com> MIME-Version: 1.0 In-Reply-To: <544B4749-9A1C-44BB-BD89-C37A7E8D86F4@nutanix.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=mst@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/29 00:53:13 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] 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: Eduardo Habkost , "qemu-devel@nongnu.org" , Aleksandar Markovic , Paolo Bonzini , Ani Sinha , Igor Mammedov , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Aurelien Jarno , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Apr 29, 2020 at 06:11:20AM +0000, Ani Sinha wrote: >=20 >=20 > > On Apr 29, 2020, at 10:58 AM, Michael S. Tsirkin wrote= : > >=20 > > o if there's a need to disable > > just one of these, commit log needs to do a better job documenting the > > usecase. >=20 > The use case is simple. With this feature admins will be able to do what = they were forced to do from Windows driver level but now at the bus level. = Hence,=20 > (a) They need not have access to the guest VM to change or update windows= driver registry settings. They can enable the same setting from admin mana= gement console without any access to VM. > (b) It is more robust. No need to mess with driver settings. Incorrect se= ttings can brick guest OS. Also no guest specific knowhow required. > (c) It is more scalable since a single cluster wide setting can be used f= or all VM power ons and the management plane can take care of the rest auto= matically. No need to access individual VMs to enforce this. > (d) I am told that the driver level solution does not persist across a re= boot.=20 >=20 > Ani Looks like disabling both plug and unplug would also address these needs. --=20 MST