grub2 as SeaBIOS payload

[Wen Wang]

Hello,

Has anybody tried to launch GRUB2 by SeaBIOS as a payload (not grub2 on
MBR)?  I am hoping to see grub2 on SeaBIOS boot menu.

I followed the coreboot wiki page to compile grub2:
git clone git://git.savannah.gnu.org/grub.git grub
cd grub
./autogen.sh
./configure --with-platform=coreboot
make

At this point it is not clear to me how to create grub2.elf and what the
role of memdisk is. I would appreciate it if somebody could clarify the
steps.

Thanks!

Wen

[WANG FEI]

I bet the solution you mentioned is to build GRUB2 as the payload of
coreboot instead of seabios.

Seabios is a legacy bios and support legacy boot, it possible can not load
grub2.elf. Please correct me if I'm wrong.

I think memdisk is only a blank disk with grub.cfg and can be created with
Linux dd command.

I'm not familiar with GRUB2, waiting for the expert to explain this.

On Fri, Jan 23, 2015 at 4:34 AM, Wen Wang 
wrote:
> Hello,
>
> Has anybody tried to launch GRUB2 by SeaBIOS as a payload (not grub2 on
> MBR)?  I am hoping to see grub2 on SeaBIOS boot menu.
>
> I followed the coreboot wiki page to compile grub2:
> git clone git://git.savannah.gnu.org/grub.git grub
> cd grub
> ./autogen.sh
> ./configure --with-platform=coreboot
> make
>
> At this point it is not clear to me how to create grub2.elf and what the
> role of memdisk is. I would appreciate it if somebody could clarify the
> steps.
>
> Thanks!
>
> Wen

[Paul Menzel]

Dear Wen,

welcome to coreboot!

Am Donnerstag, den 22.01.2015, 23:34 -0500 schrieb Wen Wang:
> Has anybody tried to launch GRUB2 by SeaBIOS as a payload (not grub2 on
> MBR)?  I am hoping to see grub2 on SeaBIOS boot menu.

Yes, I did. You can press F12 (or the configured key) and select the
GRUB 2 payload. Also make sure to enable support for payloads in SeaBIOS
Kconfig menu.
> I followed the coreboot wiki page to compile grub2:
> git clone git://git.savannah.gnu.org/grub.git grub
> cd grub
> ./autogen.sh
> ./configure --with-platform=coreboot
> make
>
> At this point it is not clear to me how to create grub2.elf and what the
> role of memdisk is. I would appreciate it if somebody could clarify the
> steps.

You can look at `payloads/external/GRUB2/Makefile.inc` in coreboot’s
source to see how it is built when selected as payload in the Kconfig
system.

The following additional steps should get you going.

$ make default_payload.elf

Then go to the coreboot directory. Add a symlink to the built GRUB
payload file and add it compressed to the file `img/grub.lzma` in the
CBFS (coreboot file system) of your coreboot firmware image using
`cbfstool`.

$ ln -s path/to/default_payload.elf grub2.elf
        $ build/cbfstool build/coreboot.rom add-payload -f grub2.elf -n img/grub.lzma -c lzma

Add the GRUB configuration file to `etc/grub.cfg` in the CBFS of your
coreboot firmware image.

$ build/cbfstool build/coreboot.rom add -f /boot/grub/grub.cfg -n etc/grub.cfg -t raw

Then write the image to the flash ROM chip.

If it works for you, it’d be great if you added it to the Wiki.

Thanks,

Paul