Re: [9fans] loading plan 9 directly from linuxbios

[ron minnich <rminnich@lanl.gov>]

On Wed, 29 Oct 2003, Charles Forsyth wrote:

> the deeper problem is that (as i understand it) you're entering the code
> in real mode, which is of course quite unreal.  in that case you'll need
> to do what 9load does in l.s (using x16.h) to write the real mode code,
> because 8a/8l isn't very good at 16-bit code (though 8l could make it
> easier, with some as yet unquantified amount of work).

Entering from linuxbios and also from 9load, you are entering plan 9 in
32-bit protected mode with the gdt set up. The issue from linuxbios is
that the gdt is not Plan9-compatible. I think it is probably good hygiene
for plan 9 to be able to operate under other loaders than 9load, so
overall it is probably good for Plan 9 to assume

- machine is in protected mode (but no paging turned on)
- gdt is maybe right, but maybe wrong
- lgdt can be used in 32-bit mode
- plan 9 should reload the gdt in l.s, 32-bit instructions, before
  it sets up paging

ron