[coreboot] YABEL: Yet another (legacy) BIOS Emulation Layer

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Thu Nov 27 16:36:18 CET 2008

Hi Pattrick,

thanks for offering your code. We are definitely interested.

On 27.11.2008 16:10, Pattrick Hueper wrote:
> Hi,
> for the IBM SLOF OpenFirmware used in the YDL PowerStation, i
> developed a BIOS emulation Layer based on x86emu. It is successfully
> initialising several VGA cards in the PowerStation.
> Since the SLOF version for the PowerStation is released under a BSD
> license, i tried to integrate it into coreboot-v3 and succeeded today.
> It initializes the cirrus card of an unpatched qemu 0.9.1-5ubuntu3.
> (much slower than vm86 but i couldnt get it to initialize with the
> current x86emu)
> Using coreinfo as payload, i verified, that the console is working.


> I would like to know, wether you guys are interested in this code, i
> think it could basically be a replacement for the current x86emu code.

AFAIK current x86emu in coreboot has been optimized for size and may
differ substantially from other x86emu implementations.

> Since x86emu is BSD licensed as well, i think integrating the biosemu
> code into coreboot should not be a problem?

As long as YABEL is BSD or LGPL or GPL, I don't see any license problems.

> While working for IBM i also tried to initialize a UltraIDE card and
> almost got it to do some UDMA reads from a disk... and a ethernet card
> which started to execute the PXE stack. That code however is not
> released but based on the biosemu code.
> I am not sure where to go from here... i need to wait for the latest
> SLOF release to appear on the developerworks website
> http://www.ibm.com/developerworks/power/pa-slof/ which has some fixes.
> After that i could create a patch series or git repository for review?

A patch series would be cool for me, but I don't know what everybody
else wants.

> Coming from a PPC background i thought about trying to get coreboot-v3
> and the biosemu to run in qemu-ppc... Has anybody tried that before?
> Would trying this make sense at all?

coreboot v3 currently has no PPC code. However, the architecture should
be clean enough to accommodate PPC easily. We have some PPC code in
coreboot v2. If you are interested in working on PPC for v3, please go
ahead. It would certainly make a great addition.

> I dont currently have any hardware running coreboot, otherwise i could
> maybe try to recreate the code to get other PCI cards to initialize...

IIRC the Asus P2B-F and P3B-F are supported by coreboot and available
for ~5 EUR on ebay.



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