# kvm video problem

## Princess Nell

I started playing with kvm, but I seem to have a problem with the video configuration. In full screen mode,

even when I match the host display resolution on this laptop screen, kvm doesn't use the full screen height,

it leaves black bars at top and bottom, making the display look squished. That's with -vga std. -vga vmware

offers less suitable resolutions (yes, I have the video drivers from vmware tools installed).

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## Hu

KVM does not change the resolution of the guest when you go to full screen mode.  You will need to set an appropriate resolution in the guest through its normal mechanisms.  This can be problematic if you run a guest operating system which is picky about the resolutions it will present or if you use a resolution greater than the emulated video card supports.

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## Princess Nell

The native guest resolution is fine and correct. Qemu-kvm simply doesn't use the full height of the display.

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## Hu

So the "full screen" KVM has black bars and it also fails to show content from the guest?

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## Princess Nell

It shows the content fine. I didn't say it doesn't    :Wink: 

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## Hu

If all pixels that the guest attempts to draw are visible and there are also black bars visible, then the guest is not providing enough pixels to fill up the screen.  Presumably, the guest draws the entire screen area in its chosen resolution.  From that, it follows then that the guest screen resolution is too low.  Perhaps it would help if you would post some hard numbers.  What is the pixel resolution of the host display when you do this?  What resolution did you configure in the guest?

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## Princess Nell

On the host:

```

screen #0:

  dimensions:    1280x800 pixels (332x212 millimeters)

  resolution:    98x96 dots per inch

  depths (7):    24, 1, 4, 8, 15, 16, 32

```

On the guest, the display resolution is 1280x800, 32 bit.

But there is good news: the problem went away with the upgrade to xorg 1.7 and kernel 2.6.32-r7!

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