Grub to Grub2

matiasar · 04-23-2010, 02:29 PM

Hello!
I'm finding a little hard moving from the old Grub to the newer Grub2.
Really I found harder to add a menuentry in /etc/grub.d/40custom for Linux partitions. With Grub that used to be easy. May be there's some easy way with Grub2 too.
Within my first HD I run Debian Squeezy (with Grub2 as boot loader). I installed a second hd in which I installed Ubuntu, just for some testings Grub2 features porpouses. So, I added an entry in /etc/grub.d/40_custom

Code:

# Ubuntu
menuentry       "Ubuntu 8.04.4 LTS, kernel 2.6.24-27-generic" --class debian --class gnu-linux --class gnu --class os {
        insmod ext2
        set root='(/dev/hdb,1)'
        search --no-floppy --fs-uuid --set c3fc10db-cd1d-476b-9780-d6eb5e56ebc5[/B]
        echo Cargando Linux 2.6.24-27
        linux   /boot/vmlinuz-2.6.24-27-generic root=UUID=c3fc10db-cd1d-476b-9780-d6eb5e56ebc5 ro quiet
        echo loading initial ramdisk...
        initrd  /boot/initrd.img-2.6.24-27-generic
}

Finally it worked. But I'd like to know a few things:

1) For the entry to work I had to add: "--class debian --class gnu-linux --class gnu --class os" after the entry display name. Why is needed?

2) What is the option "search" to?

search --no-floppy --fs-uuid --set c3fc10db-cd1d-476b-9780-d6eb5e56ebc5[/B]

3) set root: In Grub2 does it support the old notation: set root=(hd1,1) ?

Really without those options Grub2 didn't runned the kernel on Ubuntu's partitions. I'd relly like to know why they are needed in Grub2.

Thanks in advance,
Matías

martvefun · 04-24-2010, 08:30 AM

I find also grub2 harder to configure

if it can help you :

Code:

menuentry "Arch Linux" {
	insmod ext2
	set root=(hd0,7)
	search --no-floppy --fs-uuid --set 5000f957-3345-4c17-adf9-6d6e5e8c4048
	linux /vmlinuz26 root=/dev/sda10 ro init=/sbin/bootchartd
	initrd /kernel26.img
}
menuentry "Ubuntu 9.10 2.6.31-19" {
	insmod ext2
	set root=(hd0,9)
	search --no-floppy --fs-uuid --set 475c6415-680f-4155-bc0c-e91e7ebec36b
	linux /boot/vmlinuz-2.6.31-19-generic-pae root=UUID=475c6415-680f-4155-bc0c-e91e7ebec36b ro quiet splash
	initrd /boot/initrd.img-2.6.31-19-generic-pae
}

1) So no --class for me and it works fine. What happens if you remove it ?
2) I think "search" is to tell grub where the root partition is.
3) Both "root=(hd0,x)" and "root=UUID=..." works

matiasar · 04-26-2010, 08:26 AM

Martvefun,

Thanks for your examples!
Grub2 actually seems harder may be because isn't so easy to find documentation.
Based in your tips I did some testing and worked. Really the "class" options are not a must.

Code:

menuentry       "Ubuntu 8.04.4 LTS, kernel 2.6.24-27-generic" {
        set root='(/dev/hdb,1)'
        search --no-floppy --fs-uuid --set /dev/hdb1
        echo Cargando Linux 2.6.24-27
        linux   /boot/vmlinuz-2.6.24-27-generic root=/dev/hdb1 ro quiet
        echo Cargando ramdisk inicial ...
        initrd  /boot/initrd.img-2.6.24-27-generic

But "search" parameter seem to be a must with Grub2.

I found some examples in /usr/share/doc/grub-common/examples/grub.cfg. But the example for GNU Linux lacks of "search" option. But for me, without search it didn't work.

Code:

#For booting GNU/Linux (example from /usr/share/doc...
menuentry "GNU/Linux" {
        set root=(hd0,1)
        linux /vmlinuz root=/dev/sda1
        initrd /initrd.img
}

I'll keep on doing some research.
Thanks a lot. Merci beaucoup!

ronlau9 · 04-26-2010, 09:38 AM

This might be some help www.ubuntuforums.org/showthread.php?t=1195275

matiasar · 04-27-2010, 06:40 AM

That's a very good link. Thanks a lot for it.
Really one with more details on Grub2 I've found.

Regards,
Matías

JZL240I-U · 04-30-2010, 07:47 AM

Here is one more:

http://www.dedoimedo.com/computers/grub-2.html