Re: [PATCH] split realmode and loader routines out of startup.S

[Robert Millan]

On Fri, Jan 04, 2008 at 06:15:17PM +0100, Jeroen Dekkers wrote:
> At Tue, 16 Oct 2007 23:09:07 +0200,
> Robert Millan wrote:
> > This patch splits realmode and loader routines out of startup.S.  The idea
> > is that the LinuxBIOS port can be adapted to share more code with the rest
> > of GRUB instead of duplicating it.
> > 
> > This is quite critical stuff, so even if the change seems trivial I'd 
> > suggest
> > being careful, since I don't trust myself too much.  Of course, I've tested
> > that it can still boot Linux and Multiboot (on qemu only).  Perhaps testing
> > on real hardware would be appropiate (but I don't have this handy atm).
> <SNIP>
> >     * kern/i386/pc/startup.S (protstack): Moved to ...
> >     * kern/i386/realmode.S (protstack): ... here.
> >     * kern/i386/pc/startup.S (gdt): Moved to ...
> >     * kern/i386/realmode.S (gdt): ... here.
> >     * kern/i386/pc/startup.S (prot_to_real): Moved to ...
> >     * kern/i386/realmode.S (prot_to_real): ... here.
> > 
> >     * kern/i386/pc/startup.S: Include `kern/i386/loader.S' and
> >     `kern/i386/realmode.S'.
> 
> Why did you move prot_to_real to realmode.S, but not real_to_prot?
> That seems a bit strange to me...

Because on i386-pc, GRUB wants to do both things, but on i386-linuxbios,
you start in protected mode and only want to switch once to real mode when
booting Linux.  There's no way back AFAICT.

-- 
Robert Millan

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<DRM> What use is a phone call, if you are unable to speak?
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