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Sun Dec 9 17:34:17 CET 2012

Small Linux' (DSL). With the latter I had to download the full X server =
package to get the Via driver, and change configuration slightly to make =
sure that this driver was the one that ran rather than the default Vesa =
driver. Both of these setups use 2.4.x kernels, and I have no experience =
with 2.6.x.

To make Linuxbios VESA compatible would thus require Linuxbios to create =
a persistent int 21 handler in 16 bit code. It could be made persistent =
by creating it somewhere in the 0xf000 segment along with the various =
tables which it creates.

The int 21 handler itself is fairly trivial - it just seems to return =
certain values describing the environment in which it is running:
- The type and speed of main memory - which in turn is used to limit the =
max resolution and refresh rate of the display so as not to hog main =
memory bandwidth on slower memory
- The type of display chosen and saved in CMOS - CRT, TV, Flat Panel
- The size of a flat panel etc.

The current int 21 handler simply returns hard coded values for these =
i.e. 266Mhz DDR ram, and CRT display only.
Unless anyone feels that they would like to add such a handler, I would =
thus recommend that folk stick with the native chipset drivers, and make =
sure that they are configured to not use Bios calls for setting the =
graphics mode.

Other mailings have suggested that the Via 1.1.16 vga bios does not =
work, whereas the 1.1.13 bios does. I suspect that Via have extended or =
changed their definition of the int 21 call between these two versions - =

Nick Barker

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