Re: Chainloading on a LibreBoot X200

[Eduardo Ochs]

Hi Pascal,

> I guess the pendrive is set up to be booted from BIOS (or UEFI) ?
> AFAIK BIOS chainloading works only if BIOS services are available.
> Do Libreboot provide BIOS services and can its GRUB payload use them ?
> The device names you use such (usb0) and (ahci0) indicate that GRUB
> uses native (or coreboot ?) drivers, not BIOS drivers which would give
> names such as (hd0).
>
> (...)
>
> I guess this is grub-pc (for BIOS) too ?
> Maybe you need to use grub-coreboot ?
> How do yo boot the main OS from Libreboot/GRUB payload ?

sorry... it took me many hours of research, and some hours on the IRC
channel, to understand that libreboot - that is coreboot-based - does
have a chainloader command but it is not fully functional, and that
libreboot people are quite happy without chainloader because they have
workarounds that I didn't understand before...

Here are the working entries in my grub.cfg. To discover how to make
an entry for booting the pen drive I had to understand the files in
its isolinux/ directory, especially isolinux/live.cfg.

  menuentry 'Boot /dev/sda6 (with home on /dev/sda7)' --hotkey='m' {
    set root=(ahci0,6)
    linux /vmlinuz root=/dev/sda6 rw
    initrd /initrd.img
    boot
  }

  menuentry 'Boot a pen drive made with live-build without chainloading'
--hotkey='b' {
    set root=(usb0,gpt1)
    linux  /live/vmlinuz boot=live components quiet splash
    initrd /live/initrd.img
    boot
  }

I've made a page about all this:

  http://angg.twu.net/grub.html

Cheers and thanks =),
  Eduardo Ochs