RE: [Xen-users] Direct dom0->domU execution of commands (without console or network)

[Steve Brueckner <steve@xxxxxxxxxxxxxx>]

The console is a fancy interface to a pts device, and apparently it's
possible to be more direct.  Check this out:

http://armyofevilrobots.com/node/396

Steve Brueckner, ATC-NY 

-----Original Message-----
From: Fermín Galán Márquez [mailto:fermin.galan@xxxxxxx] 
Sent: Friday, April 13, 2007 3:47 PM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Cc: 'David Fernández'
Subject: [Xen-users] Direct dom0->domU execution of commands (without
console or network)

Hello,

I'm interested in dom0-domU advanced interaction mechanism improving the
conventional console or network interaction. In particular, I would like to
know if there is some "direct" dom0 to domU command execution mechanism. Let
me clarify with an example:

Suppose we want to issue the following command to a particular domU, let's
say domU ID 3:

   ifconfig eth0 down

(domU ID and command are just an example, they could be any others)

The conventional procedure would be to use 'xm console 3', login in the
console (if not already logged in a previous console access) typing and
executing 'ifconfig eth0 up', then (optionally) deattaching the console.

This procedure is ok for simple interaction with domU, but it could be very
tedious when you plan to issue long sequences of commands in each domU
(maybe automated in a centralized script running in dom0). What I meaning is
something like that:

   xm execute 3 'ifconfig eth0 down'

(I have revised "man xm" and I haven't found nothing like that...)

Maybe is a bit out of the scope of the list, but for whoever that knows User
Mode Linux and uml_mconsole, what I meaning is some similar to "uml_mconsole
exec".

As a matter of fact, there are two possible workarounds, but they have
limitations:

1. Issue the command through the network:

   ssh <ip_of_domU_3> 'ifconfig eth0 down'

Limitation: network has to be properly configured in dom0 and domU.

2. Play with 'xm console' and expect (http://expect.nist.gov/)

Limitation: expect programming is *very* difficult to maintain.

Do you know if there is some direct interaction mechanism in Xen like the
one I've described? In negative case, do you think it would be desirable to
develop one?

Thanks in advance!

Best regards,

--------------------
Fermín Galán Márquez
CTTC - Centre Tecnològic de Telecomunicacions de Catalunya Parc Mediterrani
de la Tecnologia, Av. del Canal Olímpic s/n, 08860 Castelldefels, Spain Room
1.02 Tel : +34 93 645 29 12 Fax : +34 93 645 29 01 Email address: fermin dot
galan at cttc dot es 



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