Re: [Qemu-devel] Announcing qboot, a minimal x86 firmware for QEMU

[Kevin O'Connor]

On Mon, May 25, 2015 at 02:52:51PM +0200, Paolo Bonzini wrote:
> On 23/05/2015 01:23, Kevin O'Connor wrote:
> > I'm curious if you've tried profiling SeaBIOS to see where it is
> > spending unnecessary time?
> 
> No, I really wanted to get the absolute minimum time needed to get to
> the kernel.  I announced it publicly because I think it's also instructive.
> 
> > I wonder if a stripped down SeaBIOS could
> > obtain sufficient performance.
> 
> It most likely could.  However, some of the features (e.g. booting
> vmlinuz from parallel flash or, in the future, from persistent memory)
> probably do not fit SeaBIOS very well.  One would have to redo them
> otherwise, for example using a DMA interface in fw_cfg.

I think adding vmlinuz and/or multiboot support to SeaBIOS would be
generally useful (and not difficult).

If a kernel was placed in memory (or memory-mapped flash) then I think
it would be reasonable to have SeaBIOS obtain its address from (an
unoptimized) fw_cfg and deploy it.

-Kevin