about VGA support in voyager2 board

SONE Takeshi ts1 at cma.co.jp
Thu Aug 28 09:32:01 CEST 2003

On Thu, Aug 28, 2003 at 07:26:30AM -0600, ron minnich wrote:
> > It's also worth mentioning that the current code works only
> > if the "trampoline" code is also located below 64K.
> oops. What do you mean by "trampoline" here? 

32-16-32 transition in vgabios.c and 16-32-16 transition in idt.c.
The problem is that 16-bit code segment descriptor (0x28) has base address
zero and 64K limit.

(I studied these code to implement my own 32-bit legacy services
but abandoned it because vm86 starts looking inevitable...)

Perhaps we can put these functions in a special section and
modify the ld script to put this section near the beginning of image
so that these functions will be located below 64K for most cases.

> Do you think you could test a new vgabios.c for me?

My EPIA doesn't need the fix but I can confirm the fix doesn't break it.


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