[coreboot] YABEL and images in LAR files

Corey Osgood corey.osgood at gmail.com
Fri Dec 19 20:52:38 CET 2008

On Fri, Dec 19, 2008 at 1:57 PM, Pattrick Hueper <phueper at hueper.net> wrote:

> Hi,
> well following the BIOS spec (i think its somewhere in the PNP BIOS
> spec... i have to check... ) the BIOS copies the ROM to RAM... since
> YABEL uses its own "virtual" memory it _has_ to copy the ROM to its
> RAM... also some of the cards i have used do actually modify the
> memory where the ROM is stored, so it has to be in the virtual RAM.
> Currently, the ROM is always copied from the Expansion ROM bar of PCI
> devices.... i havent had to initialize any onboard devices. If there
> is a parameter to run_bios that points to the location of the Option
> ROM i could pass that parameter to YABEL and only use the Expansion
> ROM BAR if that parameter is not set (null?). But IIRC i still have to
> copy it to the virtual memory.
> If it helps coreboot to know where the Option ROM image is after
> execution of the ROM, i guess YABEL could return the location of the
> ROM (the length which could be changed during execution is part of the
> ROM, so coreboot could figure out how much to copy back if it decides
> to do so.
> I am thinking of buying a x86 board to do coreboot development, i am
> wondering which one would be a good choice with regards to YABEL and
> maybe SEABIOS development? Any recommendations?
> My requirements:
> coreboot-v3 and preferably v2 "compatible"
> PCI and PCIe slots
> since Myles mentioned onboard devices with ROM in LAR that would be
> very interesting too...
> "affordable"
> I am really unsure what else to look for... Flash Chip Types? Processor?
> Cheers Patty

A used i810 board? You can get the for next to nothing off ebay, they're
fairly simple to port (almost every possible super io is supported), have
onboard video and pci for an expansion card, and the onboard video works in
v2 now, iirc. No v3 support though.  You can get a Jetway J2F2-series for
around $100, that board is in v2 working well and is almost booting linux in
v3. The downside is that the video BIOS in that one is very picky, I had to
copy BOCHS to 0xf0000 and run it with vm86 in v2.


> On Fri, Dec 19, 2008 at 6:05 PM, Myles Watson <mylesgw at gmail.com> wrote:
> >
> >
> >> -----Original Message-----
> >> From: Jordan Crouse [mailto:jordan at cosmicpenguin.net]
> >> Sent: Friday, December 19, 2008 9:48 AM
> >> To: Myles Watson
> >> Cc: Pattrick Hueper; Coreboot
> >> Subject: Re: [coreboot] YABEL and images in LAR files
> >>
> >> Myles Watson wrote:
> >> > Patty,
> >> >
> >> > For some devices, Coreboot has the ROM image in a section of the ROM.
> >> It
> >> > copies that image to memory and passes a pointer to run_bios.
>  Actually,
> >> > right now Coreboot copies the ROMs to RAM for devices too.  YABEL
> works
> >> when
> >> > the ROM is accessible from the device (by ignoring the fact that
> >> Coreboot
> >> > already copied it), but not in the case that Coreboot expects it to be
> >> run
> >> > from RAM.  Do you have any thoughts on how to handle this case?
> >> >
> >> > Thanks,
> >> > Myles
> >>
> >> We don't _have_ to copy it to RAM, it just never occurred to us that it
> >> shouldn't be.  However, if we leave it on the ROM, don't we hit the same
> >> issue with the shadowed memory that we did with the shared functions a
> >
> > I think it needs to be copied to RAM.  I was just wondering who should do
> > that copy.  YABEL doesn't have a way of knowing where to find the ROM for
> > onboard devices that have their ROM images imbedded in a LAR file.  That
> > information isn't in the ROM BAR.  That's why we pass the address to
> > bios_run.  Right now YABEL just ignores that address.
> >
> > I was just trying to think of the cleanest way to handle the following
> > cases:
> > 1. The device is an add-in card with its own ROM.
> > 2. The device is onboard and coreboot has the ROM image.
> > 3. The device is an add-in card and coreboot wants to initialize it with
> a
> > different ROM.
> >
> > I know 3 is unusual, but it might be useful sometimes.
> >
> > Thanks,
> > Myles
> >
> >
> --
> coreboot mailing list: coreboot at coreboot.org
> http://www.coreboot.org/mailman/listinfo/coreboot
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.coreboot.org/pipermail/coreboot/attachments/20081219/4325b351/attachment.html>

More information about the coreboot mailing list