[LightDM] How to change depth of display from 24-bit to 16 or 32?

[Ken Stailey]

Hi,

I am testing Oneiric on QEMU guests and they default to 24-bit X display.

How can I change that to 24-bit to 16 or 32 for testing?

Current tickets:
https://bugs.launchpad.net/bugs/843448
https://bugs.launchpad.net/bugs/844764

Searching shows that X is started by lightdm.

lightdm man page says:

      --xserver-command=COMMAND
              Command to run X servers

I can't find the lightdm.conf man page or other documentation.  I just want to make lightdm add "-depth 32" to its invocation of X.

How do I do that?

Thanks