[libvirt] PATCH: Support SDL configuration for QEMU driver

Daniel Veillard veillard at redhat.com
Fri Oct 3 14:49:13 UTC 2008

On Thu, Oct 02, 2008 at 06:09:21PM +0100, Daniel P. Berrange wrote:
> QEMU has two modes of providing a graphical display, VNC and SDL. Now most
> of our tools just use VNC, but occasionally people want to use SDL for 
> some crazy reason. We already support this in Xen driver, but the QEMU
> impl has been rather lacking. At the moment if you ask for a SDL display
> it'll only happen to work if you had the $DISPLAY environment variable
> set when you started libvirtd - you probably don't.

  Hum, it would be really nicer if everything was driven only by
command line options, but i can understand why the QEmu guys made it
that way, at least historically

> The generic XML parser allows for two attributes on the <graohics>
> element for setting the display and xauth filename, so this patch updates
> the QEMU driver to use this data if available. This means we have to 
> start setting environment variables when invoking QEMU, so this patch
> is a little larger than would otherwise be expected.

  Okay i think I understand the patch, i didn't find anything suspicious
in the C code diff (except missing -p ?)

  The tests diff looks simple and systematic, and for the test program
this looks fine too.


> Now previously since we just use 'execv' the QEMU process would just
> inherit all libvirtd's environment variables. When we now use execve()
> no variables are inherited - we have to explicitly set all the ones
> we need. I'm not sure what we should consider the mimimum required?
> I'm merely setting  'LC_ALL=C' to ensure it runs in C locale. Do we
> need to set $PATH for QEMU - maybe ? Anything else which is good
> practice to set ?

  if there is an LD_PRELOAD, pass it maybe, that can be really useful
at times especially when debugging.


Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel at veillard.com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/

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