Re: [coreboot] Status of SeaBIOS VGA bios.

[Kevin O'Connor]

On Wed, Oct 26, 2011 at 12:16:32AM +0100, Julian Pidancet wrote:
> Hi,
>
> I stumbled across the vgasrc directory in the SeaBIOS git tree which
> seem to contain the source of a VGA Bios. I havn't found any related
> documentation nor announcements regarding this, and there is no
> Makefiles or scripts to build it. That's why I'm enquiring here about
> the status of this project.

You can build the vgabios by running:

make out/vgabios.bin

There was a brief note on the vga code some time back:

http://www.coreboot.org/pipermail/coreboot/2009-May/047775.html
> I've got several questions:
> What is the general status of this project ?

I started converting the VGA bios from the "lgpl vga bios" project (
http://savannah.nongnu.org/projects/vgabios/ ) a couple of years ago.
I converted the base code, but did not have time to convert the "VBE"
or the "cirrus" code.

There was also an effort a few years back to get the code running on
real hardware that had some success.
> Is this code intended to be executed in a 32bit environment by
>
> transitionning from 16bit to 32bit mode for each BIOS call as SeaBIOS
> already does ?

The current seabios vgabios code runs exclusively in 16bit mode.
(Note, SeaBIOS also has some calls handled entirely in 16bit mode as
well.)
> Is this code able to run independantly from SeaBIOS ?

It should - but I've never tested it that way.
> How can I build the sources ?

make out/vgabios.bin
> I am currently working on a emulated graphic adapter for Xen and I
> would like to implement a VBE driver for it. This VGA BIOS seems to be
> a good base for that kind of work. Would that be possible ?

It should work.  Ideally, someone would complete the port of the "lgpl
vgabios".  This involves translating the remaining 16bit assembler to
C code and then doing lots of testing on the result.

-Kevin

Status of SeaBIOS VGA bios.

[Julian Pidancet]

On Wed, Oct 26, 2011 at 1:26 AM, Kevin O'Connor  wrote:
> You can build the vgabios by running:
>
> make out/vgabios.bin

Great, that was easy :)
> I started converting the VGA bios from the "lgpl vga bios" project (
> http://savannah.nongnu.org/projects/vgabios/ ) a couple of years ago.
> I converted the base code, but did not have time to convert the "VBE"
> or the "cirrus" code.

Since my plan requires some VBE support code anyway, I guess I would
have to convert it as a preliminary task, right ?
> It should work.  Ideally, someone would complete the port of the "lgpl
> vgabios".  This involves translating the remaining 16bit assembler to
> C code and then doing lots of testing on the result.

I havn't tried to run the ROM yet. Could you be more precise about
what works (or what is supposed to be working), what's not, and what
exactly remains to be translated ? I'd like to make an idea of the
amount of work required to have a ROM equivalent to vgabios.

Thanks !

[SeaBIOS] Status of SeaBIOS VGA bios.

[Gerd Hoffmann]

Hi,
> I started converting the VGA bios from the "lgpl vga bios" project (
> http://savannah.nongnu.org/projects/vgabios/ ) a couple of years ago.
> I converted the base code, but did not have time to convert the "VBE"
> or the "cirrus" code.

qemu uses the lgpl vga bios too, slightly modified version, git tree is
at git://git.qemu.org/vgabios.git
> > I am currently working on a emulated graphic adapter for Xen and I
> > would like to implement a VBE driver for it. This VGA BIOS seems to be
> > a good base for that kind of work. Would that be possible ?
>
> It should work.  Ideally, someone would complete the port of the "lgpl
> vgabios".  This involves translating the remaining 16bit assembler to
> C code and then doing lots of testing on the result.

Just curious: What kind of graphic adapter do you plan to create?

The vgabios+qemu have two different ways to handle VBE support:  One is
the cirrus emulation, where the vgabios programms the cirrus like real
hardware.  The other one is the bochs vbe support.  That is basically a
side channel which allows the bios to program video modes in a very
simple way using special I/O ports.  All non-cirrus vga cards emulated
by qemu (std, vmware, qxl) support that.

Supporting the bochs vbe interface for one more model is just a matter
of adding a few lines with the PCI IDs to the vgabios.git Makefile.  If
you don't want or don't can go this route it is most likely easier to go
with the C version in the seabios.git tree than touching the vgabios.git
assembly code.

HTH,
  Gerd