[LinuxBIOS] comments about Linux BIOS

Stefan Reinauer stepan at coresystems.de
Mon Jan 8 17:32:20 CET 2007

* ron minnich <rminnich at gmail.com> [070108 15:50]:
> if you're really determined to support this, I think the best way to
> do it is to build on our emulator. I.e. load the MBR and support its
> calls via emulation, not direct execution a la ADLO.

And how do you do the transition to native x86 execution? Your scenario
would mean to emulate execution of the Windows bootloader, so that it
can use bios callbacks. But I have no idea how to find out we're out of
the bootloader and in Windows itself. ie. no bios callbacks will follow.

> We've found the
> emulator to be very solid, and in fact, somebody is working on
> plugging it in to plan 9 to improve their VESA support. So you would
> load the MBR, run it under emulation, and take it from there.
Nothing against the success of the emulator. It is great work, and it
helped LinuxBIOS (and I suppose other projects) a lot. But emulating an
x86 machine on an x86 seems to have a whiff of a broken design. Not to
forget, that it is kind of slow, thus becoming our bottle neck in boot
times (which we still call our main advantage over legacy bios)

> The best way, in my view, is to boot linux in flash and have linux
> kexec the actual OS you want to boot.

This is not exactly going to make things faster, in the Windows/MBR case.

> But is it possible to boot Vista under Linux via kexec? That would be
> interesting.

Kexec is Linux specific. It can't do the job for any Windows or BSD, 
but will just load a Linux kernel. 

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