[coreboot] Change to use CBFS - Help needed

Harrison, Jon (SELEX GALILEO, UK) jon.harrison at selexgalileo.com
Tue Aug 18 13:26:39 CEST 2009


> -----Original Message-----
> From: Patrick Georgi [mailto:patrick at georgi-clan.de] 
> Sent: 18 August 2009 11:08
> To: Harrison, Jon (SELEX GALILEO, UK)
> Cc: coreboot at coreboot.org
> Subject: Re: [coreboot] Change to use CBFS - Help needed
> Am 18.08.2009 10:30, schrieb Harrison, Jon (SELEX GALILEO, UK):
> > Hmmm. I guess that means that a CBFS build automagically installs
> > VGA bios and sets the PCI_ROM_ADDRESS reg in the correct device, and
> > since this 'should' be relocatable I should simply remove my NB code
> > that installs the VGA BIOS manually, and hope for the best.
> >    
> Sounds like you reimplemented quite some things we have in 
> coreboot already.

Possibly, but my starting point was the epia-m and as this build was
reasonably well documented and very similar to the epia-n(l), that's the
way I went.

> > At what stage in the init process does the PCI expansion ROM get
> > installed ? Is it necessary to call something from coreboot to make
> > happen ?
> >    
> We have several ways to execute option ROMs, one using the 
> realmode of the CPU (under the misleading name VM86) and two x86 
> emulators (x86emu and yabel). All of them also provide some BIOS
> (interrupts) to make the option ROMs happy, but sometimes the VGABIOS
requires some 
> special calls that must be added to them.

Yes, well any pointers to good (working!) coreboot friendly examples ?
I already have a real mode execution environment which I don't want to
have to tinker with too much. 

> > Bochs as in Bochs BIOS, is needed to provide some callback support
> > the vendor VGA BIOS. It could be considered as an option rom....
> > of. It doesn't matter where it is in Flash so long as it can be
> > programatically from coreboot, as it needs to be located in a
> > location in RAM for the legacy VGA to find it.
> >    
> So the VGA option ROM calls into the BIOS directly, instead of using 
> interrupts? That's quite unusual. And once the option ROM is 
> executing using the coreboot mechanisms, there is some BIOS
> around for it.

Mabey unusual, but it seems to be the way that the older Via Award VGA
BIOS operates.

I really don't have the time or inclination to get into a protracted
re-structuring of the code right now, after all the effort it's taken to
get to this point. I'm looking for the quick hack option that'll get me
up and running again. If I knew how to locate and find the binary data
in flash then I could more or less preserve my current infrastructure
and worry about making it more coreboot friendly later.

> Patrick
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