Re: [Qemu-devel] Why is SeaBIOS used with -kernel?

[Gerd Hoffmann]

On Fr, 2016-04-01 at 11:17 +0100, Richard W.M. Jones wrote:
> On Fri, Apr 01, 2016 at 11:18:30AM +0200, Gerd Hoffmann wrote:
> >   Hi,
> > 
> > > I wonder how we can make use of this in qemu and downstream distros?
> > > Can we have a bios-min.bin which is used with -kernel boots?
> > 
> > We already build two seabios roms: one full featued and one slightly
> > stripped down to keep it below 128k, for backward compatibility with old
> > machine types.
> > 
> > Adding a third config for -kernel boot should be easy.  For that use
> > case we can probably also turn on seabios logging to the serial console
> > and drop sgabios.  We don't need input (no boot menu) and we also don't
> > need to hook into int10 (no grub/ipxe using that for output).
> 
> SeaBIOS logging is slow (or more likely, serial output is slow).
> And sgabios is useful for debugging.

Ah, I see.  debuglevel=1 prints too much and debuglevel=0 has no logging
at all.  We'd need seabios log at least the version banner to serial
even with debuglevel=0 to replace sgabios.

https://www.kraxel.org/cgit/qemu/log/?h=work/stripped-seabios

Not hooked into -kernel yet, so you have to use "-bios bios-kboot.bin".

Comments?

cheers,
  Gerd