Re: Kernels > 1M

tytso@mit.edu
Mon, 23 Aug 1999 14:33:25 -0400


Date: Sun, 22 Aug 1999 15:26:15 -0700
From: "H. Peter Anvin" <hpa@transmeta.com>
Zack Weinberg wrote:
> I think you're mistaken about the size of the project. Move the 16
> bit setup code to setup_arch and convert for execution in protected
> mode. I don't say this is easy, but it won't take that long for
> someone who understands the platform inside out. The code to set up a
> v86 box and call the bios is already in apm.c. Now throw away that
> stupid parameter block and put everything on the kernel command line.
> Again, not necessarily easy, but short.

The 16-bit setup code *has* to run in real mode... that's the only
reason it's 16 bit. As far as the APM BIOS, I'm sure you're aware of
the number of problems caused by APM BIOSes that don't like to be called
the way Linux calls them?

Furthermore, the APM BIOS is called using its 32-bit protected-mode
interface --- which is set up by calling the APM BIOS in real mode in
setup.S; it can't be done while you are in protected mode.

Life isn't that simple, and there's a reason why some of the code that's
in the 16-bit setup code is there, and not after we transition into
32-bit protected mode. After all, if we could move it there, we would;
life is much more pleasant once you're able to leave the 16-bit
universe.

- Ted

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