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I have a 64 bit Ubuntu 9.10 workstation with two virtualized guest OSes using KVM/QEMU. Also both 64-bit. One is Fedora 12 the other is beta of Ubuntu 10.04.

The problem is that I would like to use a larger size display that is configured by default. Both guest OSes have a maximum screen resolution of 1024x768. I would like to increase this to something like 1280x900 or 1440x900. The resolution of the host system is 1920x1080.

This configuration appears to be a result of the installation detecting the resolution being reported by the virtual screen during installation.

The only information I have found on the subject suggests modifying the xorg.conf file in the /etc/X11 directory. Neither guest system has this file.

I tried creating one by hand in the Fedora system and managed to render it completely unusable. Not a big deal as this is recently installed and can be reinstalled easily.

Is what I want to do possible? If so, how do I accomplish it?

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migrated from serverfault.com Apr 18 '10 at 16:09

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+1 This is something I'd also really like to know. My HostOS native resolution is 1920x1080 and my GuestOS (Windows 7) is also stuck @ 1024x768. I'm pretty sure (from what I've read online so far) that qemu handles the hardware virtualization but I have no idea how to configure it to work with the physical graphics card. –  Evan Plaice Jul 29 '10 at 5:30
    
Got it, see my answer. –  Evan Plaice Jul 29 '10 at 9:10

2 Answers 2

up vote 0 down vote accepted

Add the '-vga std' flag to the command line

Basically, the virtual machine loads its own virtual driver. Hardware virtualization is necessary because virtual disk images are often copied to many different systems with diverse architectures. By abstracting the hardware the vm images are capable of doing this.

By using the '-vga std' flag you make the GuestOS load a standard VGA device that should be able to support resolution equal-to-or-greater than your physical card can handle.

For more info check out this article.

Note: If you're using an older version of kvm/qemu the you might need to use the '-std-vga' flag instead.

If you aren't able to reach resolutions greater than 1600x1200 note that there are still some issues with this option.

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I have -vga std and can access high resultions from windows guests, but my ubuntu guest is stuck on 1024x768. Those linked posts are pretty old (2008 and 2010 respectively). –  Matt Connolly Oct 19 '12 at 6:21

Use the vmvga Video Card

I use virt-manager (as I'm a complete noob to kvm and libvirt).

I was able to get higher resolutions on a Windows 7 guest by changing the video card from vga to vmvga in the virtual machine's settings window.

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Me too ... but that doesn't change (always 1024x768) ! –  Bertaud May 1 at 12:35
    
i going way back in my memory here, but i think i was able to change the screen resolution within the guest OS once it booted using the vmvga card. –  papyromancer Sep 2 at 22:13

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