Re: x86 - Realmode BIOS and Code calling module

[Vojtech Pavlik]

On Thu, Aug 12, 2004 at 03:38:45PM +0200, Jakub Vana wrote:

> > Why is this better than LRMI in user mode.
> 
> I was now looking on LRMI. It must be a nice code, but It is still
> only V86 emulation. I have listen that some BIOSes use something
> called Unreal mode, that is realmode with segment registers used like
> in protected mode. There is only one way, how to set this segregs -
> switch to prot. mode, but if the BIOS try to switch when is running in
> V86 CPU generates #GP (Global Protection fault). Not if it is running
> in real Real Mode.

Well, if it's running an emulated CPU (x86emu), there are no problems
with that. Even the unreal mode could be emulated, although I have yet
to see a BIOS which uses that to handle an INT call.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR
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