[haiku-development] Re: Virtual 8086 mode support

Jan Klötzke <jan.kloetzke@xxxxxxxxxx> wrote:
> looking at the restriction not being able to change the resolution
> when running
> on the vesa driver I decided to try implementing virtual 8086 mode
> support as a
> first step. So here it is... ;-)

Very nice, that comes unexpected!

> Any interrupt or exception will cause the CPU to leave vm86 mode.
> When it was
> a general protection exception or a signal is about to be delivered
> the old
> iframe is restored and the current register state is saved to the
> user mode
> structure.
>
> I coded a very small test application and the code seems to be
> working so far.
>
> But what is missing to call the VESA bios is the ability to mmap
> 0xA000--0xFFFF
> physically into the address space of the team. Don't know if this is
> aready
> possible...

I guess you mean identity mapped, right? It should be possible to do
this by mapping the memory in the kernel via map_physical_memory(), and
then clone that area in userland using B_EXACT_ADDRESS.

Bye,
   Axel.

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