From 392d8e95c7dd3de10a20387914ac34cb12d8ff04 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 12 Nov 2020 14:40:34 +0000 Subject: docs: Move cpu-hotplug.rst into the system manual MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The cpu-hotplug.rst documentation is currently orphan and not included in any manual; move it into the system manual. Signed-off-by: Peter Maydell Reviewed-by: Alex Bennée --- docs/cpu-hotplug.rst | 142 --------------------------------------------------- 1 file changed, 142 deletions(-) delete mode 100644 docs/cpu-hotplug.rst (limited to 'docs/cpu-hotplug.rst') diff --git a/docs/cpu-hotplug.rst b/docs/cpu-hotplug.rst deleted file mode 100644 index d0b06403f1..0000000000 --- a/docs/cpu-hotplug.rst +++ /dev/null @@ -1,142 +0,0 @@ -=================== -Virtual CPU hotplug -=================== - -A complete example of vCPU hotplug (and hot-unplug) using QMP -``device_add`` and ``device_del``. - -vCPU hotplug ------------- - -(1) Launch QEMU as follows (note that the "maxcpus" is mandatory to - allow vCPU hotplug):: - - $ qemu-system-x86_64 -display none -no-user-config -m 2048 \ - -nodefaults -monitor stdio -machine pc,accel=kvm,usb=off \ - -smp 1,maxcpus=2 -cpu IvyBridge-IBRS \ - -qmp unix:/tmp/qmp-sock,server,nowait - -(2) Run 'qmp-shell' (located in the source tree, under: "scripts/qmp/) - to connect to the just-launched QEMU:: - - $> ./qmp-shell -p -v /tmp/qmp-sock - [...] - (QEMU) - -(3) Find out which CPU types could be plugged, and into which sockets:: - - (QEMU) query-hotpluggable-cpus - { - "execute": "query-hotpluggable-cpus", - "arguments": {} - } - { - "return": [ - { - "type": "IvyBridge-IBRS-x86_64-cpu", - "vcpus-count": 1, - "props": { - "socket-id": 1, - "core-id": 0, - "thread-id": 0 - } - }, - { - "qom-path": "/machine/unattached/device[0]", - "type": "IvyBridge-IBRS-x86_64-cpu", - "vcpus-count": 1, - "props": { - "socket-id": 0, - "core-id": 0, - "thread-id": 0 - } - } - ] - } - (QEMU) - -(4) The ``query-hotpluggable-cpus`` command returns an object for CPUs - that are present (containing a "qom-path" member) or which may be - hot-plugged (no "qom-path" member). From its output in step (3), we - can see that ``IvyBridge-IBRS-x86_64-cpu`` is present in socket 0, - while hot-plugging a CPU into socket 1 requires passing the listed - properties to QMP ``device_add``:: - - (QEMU) device_add id=cpu-2 driver=IvyBridge-IBRS-x86_64-cpu socket-id=1 core-id=0 thread-id=0 - { - "execute": "device_add", - "arguments": { - "socket-id": 1, - "driver": "IvyBridge-IBRS-x86_64-cpu", - "id": "cpu-2", - "core-id": 0, - "thread-id": 0 - } - } - { - "return": {} - } - (QEMU) - -(5) Optionally, run QMP `query-cpus-fast` for some details about the - vCPUs:: - - (QEMU) query-cpus-fast - { - "execute": "query-cpus-fast", - "arguments": {} - } - { - "return": [ - { - "qom-path": "/machine/unattached/device[0]", - "target": "x86_64", - "thread-id": 11534, - "cpu-index": 0, - "props": { - "socket-id": 0, - "core-id": 0, - "thread-id": 0 - }, - "arch": "x86" - }, - { - "qom-path": "/machine/peripheral/cpu-2", - "target": "x86_64", - "thread-id": 12106, - "cpu-index": 1, - "props": { - "socket-id": 1, - "core-id": 0, - "thread-id": 0 - }, - "arch": "x86" - } - ] - } - (QEMU) - -vCPU hot-unplug ---------------- - -From the 'qmp-shell', invoke the QMP ``device_del`` command:: - - (QEMU) device_del id=cpu-2 - { - "execute": "device_del", - "arguments": { - "id": "cpu-2" - } - } - { - "return": {} - } - (QEMU) - -.. note:: - vCPU hot-unplug requires guest cooperation; so the ``device_del`` - command above does not guarantee vCPU removal -- it's a "request to - unplug". At this point, the guest will get a System Control - Interrupt (SCI) and calls the ACPI handler for the affected vCPU - device. Then the guest kernel will bring the vCPU offline and tell - QEMU to unplug it. -- cgit v1.2.3