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

[Juergen Gross <jgross@xxxxxxxx>]

On 05/09/16 12:32, Ian Jackson wrote:
> 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.

Thanks for the complete text! I'll add it to the man page.

> 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.

Hmm, I think the statement:

+Obtain information of USB devices connected via the device model to a
+domain:

is absolutely correct. Which USB devices connected via the device model
won't be shown?


Juergen

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