Re: [Xen-devel] [PATCH] libxl: add "xl qemu-monitor-command"

[Ian Jackson <ian.jackson@xxxxxxxxxxxxx>]

Juergen Gross writes ("[PATCH] libxl: add "xl qemu-monitor-command""):
> Add a new xl command "qemu-monitor-command" to issue arbitrary commands
> to a domain's device model. Syntax is:
> 
> xl qemu-monitor-command <domain> <command>
> 
> The command is issued via qmp human-monitor-command command. Any
> information returned by the command is printed to stdout.
...
> +=item B<qemu-monitor-command> I<domain-id> I<command>
> +
> +Issue a monitor command to the device model of the domain specified by
> +I<domain-id>. I<command> can be any valid command qemu understands. This
> +can be e.g. used to add non-standard devices or devices with non-standard
> +parameters to a domain. The output of the command is printed to stdout.

This needs some kind of health warning.  Something like:

 Warning: This qemu monitor access is provided for convenience when
 debugging, troubleshooting, and experimenting.  Its use is not
 supported by the Xen Project.

 Specifically, not all information printed by the qemu monitor will
 necessarily be accurate or complete, because in a Xen system qemu
 does not have a complete view of the guest.

 Furthermore, modifying the guest's setup via the qemu monitor may
 conflict with the Xen toolstack's assumptions.  Resulting problems
 may include, but are not limited to: guest crashes; toolstack error
 messages; inability to migrate the guest; and security
 vulnerabilities which are not covered by the Xen Project security
 response policy.

The rest of the documentation will need adjusting.  As an example of
the incompleteness I am talking about I think the example shows only
some of the USB devices presented to the guest.

Ian.

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