[SeaBIOS] [PATCH] vgabios: Make the qemu vgabioses selectable when building for coreboot.

[Denis 'GNUtoo' Carikli]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Mon, 25 Aug 2014 11:35:14 -0400
Kevin O'Connor <kevin at koconnor.net> wrote:

> On Sun, Aug 24, 2014 at 11:45:35PM +0200, Denis 'GNUtoo' Carikli
> wrote:
> > The qemu vgabioses can be usefull in coreboot, since coreboot
> >   does support qemu.
> 
> I'm not sure why you'd want to build the QEMU vga roms when
> CONFIG_COREBOOT is set.  All it would do is rebuild the same roms that
> already come with QEMU.
I have some i945 laptops which have coreboot with the native GPU
initialization. (I've also an Alix-1c with a geode LX).

So, I wanted to have a (virtual) machine that is closer to my
coreboot machines.

The goal is to test the payloads way faster with qemu, then once ready,
to try the payload on the real hardware.

Right now qemu uses the roms that comes with it, and it probably make it
looks like a flash chip that is on the (virtual) GPU.

Here's an example of my test configuration:
Coreboot loads grub. Then grub has an entry for SeaBIOS.
At that point the goal is to have a functional SeaBIOS with keyboard
and VGA graphics.

There is a lot of possible variations for such setup:

Coreboot:
- ---------
* Both setup(i945 laptops and qemu) can run a VGA option
  rom(CONFIG_ON_DEVICE_ROM_RUN), or not.
  They can run the rom in two different ways: 
  * native(CONFIG_PCI_OPTION_ROM_RUN_REALMODE)
  * secure(CONFIG_PCI_OPTION_ROM_RUN_YABEL)
* It can use native graphics initialization
  (CONFIG_MAINBOARD_DO_NATIVE_VGA_INIT), but its selection seem to be
  forced for qemu, it's not for the i945 laptops.
* It can switch to VESA(CONFIG_FRAMEBUFFER_KEEP_VESA_MODE) or keep the
  "coreboot framebuffer mode"
  * With qemu(not yet available for the i945 laptops), it can choose a
    resolution resolution(CONFIG_FRAMEBUFFER_SET_VESA_MODE)

SeaBIOS:
- --------
* Hardware specific VGA helpers(VGAHOOKS) enabled or disabled.
* Then there is the choice of building no option
  rom(CONFIG_NO_VGABIOS), or building the "coreboot linear
  framebuffer" one (CONFIG_VGA_COREBOOT).

Given the ammount of variations, testing on qemu could save a lot of
time, even if testing on real hardware is unavoidable.

The i945 laptops don't have free software standalone VGA option roms.

But given the number of possibilites for testing on qemu, I was
wondering if disabling all the VGA related options in coreboot, and
only using SeaBIOS's vga option roms for qemu could help for getting
started.

That would give a (hopefully working) reference configuration.

Then I would step by step modify the configurations to get something
closer to the i945 laptops.

PS: Maybe someone has a hint on how to disable the "flash chip that
is on the (virtual) GPU" in qemu?

Denis.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=f+m7
-----END PGP SIGNATURE-----