Re: [SeaBIOS] [RFC PATCH] x86: Support booting SeaBIOS

[Bin Meng]

Hi Simon,

On Mon, Oct 19, 2015 at 10:51 AM, Simon Glass  wrote:
> Hi Bin,
>
> On 10 October 2015 at 02:57, Bin Meng  wrote:
> > Hi Simon,
> >
> > On Sat, Oct 3, 2015 at 10:29 PM, Simon Glass  wrote:
> > > Hi Bin,
> > >
> > > On 29 September 2015 at 11:17, Bin Meng  wrote:
> > > > SeaBIOS is an open source implementation of a 16-bit X86 BIOS.
> > > > It can run in an emulator or natively on X86 hardware with the
> > > > use of coreboot. With SeaBIOS's help, we can boot some OSes
> > > > that require 16-bit BIOS services like Windows/DOS.
> > > >
> > > > As U-Boot, we have to manually create a table where SeaBIOS gets
> > > > system information (eg: E820) from. The table unfortunately has
> > > > to follow the coreboot table format as SeaBIOS currently supports
> > > > booting as a coreboot payload. No U-Boot native support there.
> > > >
> > > > Booting SeaBIOS is done via U-Boot's bootelf command.
> > > >
> > > > This is the initial attempt to support booting SeaBIOS from U-Boot.
> > > > If the basic concept is good, I can spend time working on follow-on
> > > > patches to enable BIOS tables as well as graphics support. One issue
> > > > is that U-Boot x86 does not has a ROM file system like coreboot.
> > > > This brings difficulities to pass PCI option ROM to SeaBIOS, if we
> > > > don't modify SeaBIOS's source codes. Maybe we should promote CBFS
> > > > in U-Boot x86?
> > > >
> > > > This is tested on an Intel Crown Bay board with VGA card, booting
> > > > SeaBIOS then chain loading a GRUB on a USB drive, then Linux kernel
> > > > finally.
> > >
> > > Looks good to me. I think it is OK to use CBFS if needed - are you
> > > thinking of an option to build u-boot.rom as a CBFS filesystem?
> >
> > If using CBFS, that means we may have to abandon ifdtool? Or maybe
> > mixed usage of both tools?
>
> So far I'm not sure of the best approach. At present we have the ROM
> offsets stored mostly in Kconfig, with the MRC area in the SPI flash
> device tree node. The environment is also in Kconfig.
>
> What sort of option ROMs do you want to support? What other options
> does seabios provide?

I believe SeaBIOS can run any kind of PCI option ROMs, but I have
never tested other than vgabios. Also per coreboot's documentation,
booting Windows needs SeaBIOS.
> What does SEA stand for?

I guess it's because most of SeaBIOS's source codes are written in
'C', thus a 'C' BIOS.

Regards,
Bin