kexec --real-mode

Jamey Sharp jamey at
Wed Apr 30 17:08:42 EDT 2008

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.

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


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