Re: [Etherboot-developers] Tagged Test Image

[<ebi...@ln...>]

ke...@us... (Ken Yap) writes:

> >I'm going to comment out the gateA20_unset and see what happens.
> 
> Bingo, DOS and ROM images now load and run.

O.k.  Then we need to get a20 handling fixed in 5.1.x
That is one area 5.0 is definitely doing better.

Enabling a20 we can leave in the C code. 
But the code should:
- Test to see if a20 is already enabled.
- Test to see if we can use the bios to enable a20
- Test to see if we can directly enable a20 KBC.

And we should record how a20 was enabled so when we are in 16bit mode
we can restore a20 to the state we can in with.

I think there is something else missing from the 5.0.x a20
handling as well.

But it should not be hard to move that down to 16bit mode.

I believe some things do get grumpy if we don't disable a20
handling when we do the hand off in 16bit mode so.

But moving the disable to xstart16 looks like the right
place to do it given the consequence if we are above 1MB.

We probably did not see this earlier as -DRELOCATE was not
the default.

Eric