Re: [PATCH docs v3 2/3] qm: add document section for the pvpanic device

[Dominik Csapak <d.csapak@proxmox.com>]

some comments inline

On 10/9/26 8:59 AM, Kaiyang Wu wrote:
> Document the pvpanic device and corresponding driver requirements on
> different VMs.
> 
> Signed-off-by: Kaiyang Wu <wukaiyang@loongfans.cn>
> ---
>   qm.adoc | 38 ++++++++++++++++++++++++++++++++++++++
>   1 file changed, 38 insertions(+)
> 
> diff --git a/qm.adoc b/qm.adoc
> index 18a4fbe..5972fea 100644
> --- a/qm.adoc
> +++ b/qm.adoc
> @@ -1476,6 +1476,44 @@ tag (name used to mount the device on the guest).
>   For more information on available virtiofsd parameters, see the
>   https://gitlab.com/virtio-fs/virtiofsd[GitLab virtiofsd project page].
>   
> +[[qm_pvpanic]]
> +Pvpanic
> +~~~~~~~
> +
> +Pvpanic is a device to send system panic events to QEMU. It allows to
> +provide extra VM status and execute the specified panic action when the VM
> +system crashes.
> +
> +To add a pvpanic device run the following command:
> +
> +----
> +qm set <vmid> -pvpanic enabled=1[,action=<action>]
> +----
> +
> +A panic action can be specified to perform when the VM system crashes. Available
> +panic actions are:
> +
> +* `none`: Continue VM execution
> +* `pause`: Pause the VM
> +* `shutdown`: Shutdown the VM and exit, according to the shutdown action
> +* `exit-failure`: Shutdown the VM and exit with non-zero status
> +
> +NOTE: The default panic action is `shutdown`. However, because the shutdown
> +action is set to `pause` by default, `shutdown` and `pause` both pause the
> +VM unless manually specifying the shutdown action using custom `args`.

I'd not mention the 'args' part here. This can only become wrong
if we ever expose a shutdown action anywhere.

simply writing what the current default is should be enough.

> +
> +NOTE: VMs managed by the HA stack can set `exit-failure` to exit the QEMU
> +process completely and let the HA stack start it again.
> +
> +Linux VMs with kernel >=5.2 support pvpanic PCI device by default
> +(https://www.kernelconfig.io/CONFIG_PVPANIC_PCI[pvpanic PCI driver]).

just mentioning since when it's supported should be enough.
If we really want to record this, an official kernel link would be 
better, but it would be enough to put that in the commit message.
5.2 is already very old nowadays (> 6 years) so it's really just
a historical record, not an important requirement notice IMO

> +
> +Windows VMs require
> +https://github.com/virtio-win/kvm-guest-drivers-windows/[kvm-guest-drivers-windows]
> +to use pvpanic.

i'd leave the link out and simply mention the virtio-win drivers. Our
best practices and remaining docs should refer to windows guest drivers
already.

> +
> +FreeBSD VMs do not support pvpanic.
> +
>   [[qm_bootorder]]
>   Device Boot Order
>   ~~~~~~~~~~~~~~~~~