[arch-general] grub2 and the ISOs (Was: Re: [arch-dev-public] grub with ext4 support)

[Gerhard Brauer]

Am Mon, 29 Dec 2008 17:17:35 +0100
schrieb Thomas Bächler <thomas at archlinux.org>:

> This is interesting: On many BIOSes, grub 0.x is unable to find the
> CD drive and thus many people want us to use isolinux.

Personally i prefer isolinux as a "better" solution for ISO bootloader,
but grub's advantage is the grub shell...

>  From what you write here, it seems that you can access the CD drive 
> through another than the BIOS boot device method. It doesn't matter
> that access is slow, it only matters that we are able to load the
> kernel and initramfs on a greater number of machines. IMO, this is
> worth looking into.

You get these ata0, ata0,1, ata1 devices when adding the ata module to
grub2 image. But the problem is: No one could say on which bus the
users cdrom is (ata1, ata3,...). So the boot ends always in a grub2
shell instead showing the menu. User then must set it per Hand, like:
set root=ata1
linux /boot/vmlinuz26
initrd /boot/kernel26.img
boot

And I've tested this ata method only on VMs. I'm not sure if on real
machines the cdrom is realy detected as ata device (it wasn't detected
as normal device cd0, cd1 on real hardware if using the biosdisk
module). And i realy don't know why, on virtualbox,qemu it work's.

If one would test - the way to make a grub2 bootloader image for
mkisofs is:
grub-makeimage -o mycore.img list_of_modules
cat /boot/grub/cdboot.img mycore.img > myboot.img
myboot.img could now used as mkisofs parameter (-b) like we does it
with grub-legacy in mkarchiso.

Grub2 modular design (and the available modules) have a great potential
IMHO (not only that one could make it terrible blinking and colored,
splash shit). But there is a lack on documentation IMHO....

Gerhard