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Xvesa - VESA Bios Extensions tiny X server
Xvesa is a generic X server for Linux on the x86 platform.
Xvesa doesn't know about any particular hardware, and sets the video mode
by running the video BIOS in VM86 mode. Xvesa can use both standard VGA
BIOS modes and any modes advertised by a VESA BIOS if available. Xvesa runs
untrusted code with full privileges, and is therefore a fairly insecure
X server. Run at your own risk.
In addition to the normal KDrive server's
options (see Xkdrive(1)
), Xvesa accepts the following command line switches:
Xvesa opens all IO ports and runs your VESA BIOS, which
may be assumed to be buggy. Allowing your users to run Xvesa is probably
a security hole.
- -mode n
- specifies the VESA video mode to use. If mode n is not supported
by your BIOS and hardware, Xvesa will fail, hang your system, or cause
your monitor to explode; you are on your own. This option overrides any
- list all supported video modes. If -force was specified
before -listmodes, lists all the modes that your BIOS claims to support,
even those that the Xvesa server won't be able to use.
- disable some
sanity checks and use the specified mode even if the BIOS claims not to
- use a shadow framebuffer even if it is not strictly necessary.
This may dramatically improve performance on some hardware.
use a linear framebuffer even if one is available. You don't want to use
- pass RGB values in the order that works on broken BIOSes.
Use this if the colours are wrong in PseudoColor and 16 colour modes.
- emit diagnostic messages during BIOS initialization and teardown.
Xvesa records the current BIOS mode when it starts and
restores that mode on termination; if the video card has been reprogrammed
by another application, the display will almost certainly be trashed. The
alternative of saving and restoring the complete video card state has proven
unreliable on most video cards.
The VESA driver was written by Juliusz Chroboczek who didn't
realise what he was doing until it was too late. Keith Packard then added
support for standard VGA BIOS modes and is especially proud of 320x200
16 colour mode.
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