[CentOS-virt] Video resolution for CentOS guest

Tue Feb 24 21:15:25 UTC 2015
Robert Nichols <rnicholsNOSPAM at comcast.net>

On 02/23/2015 10:53 PM, Digimer wrote:
> Hash: SHA1
> On 23/02/15 11:11 PM, Robert Nichols wrote:
>> Would someone please point me to some reasonably current
>> instructions for getting greater than 1024x768 video resolution for
>> a CentOS 6 guest on a CentOS 6 KVM/qemu host?  When I search online
>> I find stuff from 2009 and 2010 saying, "For details see ...," and
>> linking to a URL that no longer exists, or pages that say, "You
>> need to switch from VNC to Spice," and giving a long list of
>> out-of-date instructions for doing so.  (With virt-manager it takes
>> 2 clicks to do that.  Of course it doesn't help -- still maxes out
>> at 1024x768.)
>> I've found that I can just append "vga=0x380" to the kernel
>> command line and see Plymouth come up with the full graphical boot
>> screen in the correct 1440x900 resolution, but as soon as gdm
>> starts up, the display scrambles.  I find suggestions to generate
>> an xorg.conf file, but no mention of what to put in it.  I can run
>> "Xorg -configure", but the resulting file contains nothing about
>> video modes, so it's not apparent what needs to be added.
>> I find it particularly annoying that a Windows 7 guest can set any
>> resolution I want up to 2560x1600, but a Linux guest can't go
>> higher than 1024x768.
> I played with this and found that, in fact, I had to switch the spice
> / qxl. With that change, I had no trouble pushing EL6 to much higher
> resolutions.

Thank you for the reassurance that it _should_ work. I finally got it
going.  The VM still always starts out in 1024x768 and I have to set
the higher resolution every time I log in.  For a while, that was
working only the first time I set it, and on subsequent logins any
attempt to change the resolution either locked up or caused the Xorg
server to crash.  All the RPMs verified OK and a forced fsck of the
filesystems found nothing.  I eventually just reinstalled the whole
VM, and it's working now.

The whole thing was bringing back bad memories of an ancient version
of Slackware and kernel version 0.99pl53.

Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.