diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/microvm.rst | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/docs/microvm.rst b/docs/microvm.rst index aae811a922..fcf41fc1f6 100644 --- a/docs/microvm.rst +++ b/docs/microvm.rst @@ -33,9 +33,9 @@ Limitations Currently, microvm does *not* support the following features: - - PCI-only devices. - - Hotplug of any kind. - - Live migration across QEMU versions. +- PCI-only devices. +- Hotplug of any kind. +- Live migration across QEMU versions. Using the microvm machine type @@ -106,3 +106,24 @@ disabled:: -device virtio-blk-device,drive=test \ -netdev tap,id=tap0,script=no,downscript=no \ -device virtio-net-device,netdev=tap0 + + +Triggering a guest-initiated shut down +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +As the microvm machine type includes just a small set of system +devices, some x86 mechanisms for rebooting or shutting down the +system, like sending a key sequence to the keyboard or writing to an +ACPI register, doesn't have any effect in the VM. + +The recommended way to trigger a guest-initiated shut down is by +generating a ``triple-fault``, which will cause the VM to initiate a +reboot. Additionally, if the ``-no-reboot`` argument is present in the +command line, QEMU will detect this event and terminate its own +execution gracefully. + +Linux does support this mechanism, but by default will only be used +after other options have been tried and failed, causing the reboot to +be delayed by a small number of seconds. It's possible to instruct it +to try the triple-fault mechanism first, by adding ``reboot=t`` to the +kernel's command line. |