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bh=hv2XPVgR5bcCP2jOSsAKNHO0+sgNNB4i7e2WRC6VVUw=; b=G5zgwBnWGNPHjAjPpMgjJvUFpLrvAIBiIS1+IDvbL/MzX/9mTQRmQ9674Cwhq5iZbdESR0 oHH9UkCe4zd7bMs8vk+HNP1lwqTAF8M49LIVa4F6aC6Myl9Q+8XFym/bt5dcPUfqC4uF/B LDUCWrIGzsNvwBGQjCrKDq8hpL26UGc= X-MC-Unique: lOHxZUf7MHyOD3rRDxI0IA-1 From: Cornelia Huck To: qemu-s390x@nongnu.org Subject: [PATCH 1/3] docs/s390x: document the virtual css Date: Tue, 5 May 2020 15:50:23 +0200 Message-Id: <20200505135025.14614-2-cohuck@redhat.com> In-Reply-To: <20200505135025.14614-1-cohuck@redhat.com> References: <20200505135025.14614-1-cohuck@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=205.139.110.120; envelope-from=cohuck@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/05 03:48:16 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: Cornelia Huck , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Add some hints about "devno" rules. Signed-off-by: Cornelia Huck --- docs/system/s390x/css.rst | 64 ++++++++++++++++++++++++++++++++++++ docs/system/target-s390x.rst | 1 + 2 files changed, 65 insertions(+) create mode 100644 docs/system/s390x/css.rst diff --git a/docs/system/s390x/css.rst b/docs/system/s390x/css.rst new file mode 100644 index 000000000000..8e18194a2f0a --- /dev/null +++ b/docs/system/s390x/css.rst @@ -0,0 +1,64 @@ +The virtual channel subsystem +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D + +QEMU implements a virtual channel subsystem with subchannels, (mostly +functionless) channel paths, and channel devices (virtio-ccw, 3270, and +devices passed via vfio-ccw). It supports multiple subchannel sets (MSS) a= nd +multiple channel subsystems extended (MCSS-E). + +All channel devices support the ``devno`` property, which takes a parameter +in the form ``..``. + +The default channel subsystem image id (````) is ``0xfe``. Devices = in +there will show up in channel subsystem image ``0`` to guests that do not +enable MCSS-E. Note that devices with a different cssid will not be visible +if the guest OS does not enable MCSS-E (which is true of all supported gue= st +operating systems today). + +Supported values for the subchannel set id (````) range from ``0-3``. +Devices with a ssid that is not ``0`` will not be visible if the guest OS +does not enable MSS (any Linux version that supports virtio also enables M= SS). +Any device may be put into any subchannel set, there is no restriction by +device type. + +The device number can range from ``0-0xffff``. + +If the ``devno`` property is not specified for a device, QEMU will choose = the +next free device number in subchannel set 0, skipping to the next subchann= el +set if no more device numbers are free. + +QEMU places a device at the first free subchannel in the specified subchan= nel +set. If a device is hotunplugged and later replugged, it may appear at a +different subchannel. (This is similar to how z/VM works.) + + +Examples +-------- + +* a virtio-net device, cssid/ssid/devno automatically assigned:: + + -device virtio-net-ccw + + In a Linux guest (without default devices and no other devices specified + prior to this one), this will show up as ``0.0.0000`` under subchannel + ``0.0.0000``. + +* a virtio-rng device in subchannel set ``0``:: + + -device virtio-rng-ccw,devno=3Dfe.0.0042 + + If added to the same Linux guest as above, it would show up as ``0.0.004= 2`` + under subchannel ``0.0.0001``. + +* a virtio-gpu device in subchannel set ``2``:: + + -device virtio-gpu-ccw,devno=3Dfe.2.1111 + + If added to the same Linux guest as above, it would show up as ``0.2.111= 1`` + under subchannel ``0.2.0000``. + +* a virtio-mouse device in a non-standard channel subsystem:: + + -device virtio-mouse-ccw,devno=3D2.0.2222 + + This would not show up in a standard Linux guest. diff --git a/docs/system/target-s390x.rst b/docs/system/target-s390x.rst index 7d76ae97b401..37ca032d98ef 100644 --- a/docs/system/target-s390x.rst +++ b/docs/system/target-s390x.rst @@ -23,6 +23,7 @@ or vfio-ap is also available. =20 .. toctree:: s390x/vfio-ap + s390x/css =20 Architectural features =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --=20 2.21.3