[SeaBIOS] Reducing SeaBIOS kernel entry time

[Paolo Bonzini]

On 03/07/2015 11:43, Peter Stuge wrote:
> > Hi,
> > qboot (https://github.com/bonzini/qboot) is a stripped down firmware
> > providing only what is needed to boot a Linux kernel on x86.
>
> Incredible, you have re-invented coreboot!

I'm pretty sure I didn't, unless you count reusing the cbfs format as
reinventing coreboot.

> Well, maybe not, it is Red Hat after all.
> 
> How about putting your efforts into the existing project instead,
> that way you can also draw on the significant experience within
> that project.
> 
> If you want to optimize for the Linux special case then you should
> not be using anything BIOS-related at all.

Indeed qboot is not a BIOS, it only provides a couple 16-bit services
that Linux needs (e820 and int 10h tty write).

> Try coreboot with kernel as payload.

Tried that.  Coreboot takes about 250 ms to pass control to the payload,
and there's hardly any option to remove unnecessary hardware setup.
SeaBIOS takes 165 ms with a vanilla configuration, but there are options
to remove unnecessary drivers.  qboot takes 20 ms.


Paolo