kexec --real-mode

[Jamey Sharp]

On Wed, Apr 30, 2008 at 12:35:05PM -0700, Eric W. Biederman wrote:
> ... if we could ever figure out what we are doing that confuses the
> hardware the other path could be used.

In principle, purgatory could load GDB stubs and keep them around at
least long enough to debug code running in 16-bit mode, right? It would
be nice if somebody would do that. :-)

For a lot of my recent kexec work, I found it very helpful to use the
gdbserver in qemu, though I had to abandon it eventually due to
emulation bugs.

> For video mode changing it might be possible to just run the vga
> BIOS calls and make them work.

I was relying on vesafb in the kernel I wanted to boot. It turns out
that --real-mode works great on every machine I have handy, but doesn't
work for one of my co-workers. So I'm going to see if uvesafb works
better, in the next day or two hopefully.

http://dev.gentoo.org/~spock/projects/uvesafb/

I'm hoping that running the video BIOS in an x86 emulator works
reliably, and that that's the only boot failure I encounter. :-)

Jamey