[SOLVED] Can't add linux install to grub menu

sharky · 05-15-2017, 02:24 AM

Have grub and linux mint installed on /dev/sda. The OS in on /dev/sda1. Have another linux install on /dev/sdb1. I can mount it while booted into mint and I can see the contents of /boot.

Code:

 > ll /media/lfs/boot/
total 6761
drwxrwxrwx 3 mymachine mymachine    2048 Jan 23 11:22 .
drwxrwxrwx 5 mymachine mymachine    2048 Jan 24 03:32 ..
-rw-r--r-- 1 mymachine mymachine  922342 Jan 17 11:47 initrd.gz
drwxrwxrwx 3 mymachine mymachine    4096 Jan 17 10:21 isolinux
-rw-rw-rw- 1 mymachine mymachine 5992432 Jan 15 10:32 vmlinuz

Is there a utility to add the /dev/sdb1 partition to grub.

The grub.cfg file warns not to manually edit and the syntax is very verbose so I'm not comfortable trying to manually add another menu item.

syg00 · 05-15-2017, 02:52 AM

For Mint update-grub should do it (use sudo). The actual function is provided by os-prober, which has syntax rules for recognising kernels. Whether it'll accept that, you'll only find out by trying.
If not, you'll have to build your own custom entry - see /etc/grub.d/40_custom. Plenty of how-to's online.

sharky · 05-15-2017, 07:06 AM

Quote:

Originally Posted by syg00

For Mint update-grub should do it (use sudo). The actual function is provided by os-prober, which has syntax rules for recognising kernels. Whether it'll accept that, you'll only find out by trying.
If not, you'll have to build your own custom entry - see /etc/grub.d/40_custom. Plenty of how-to's online.

Added this entry to 40_custom.

Code:

menuentry "Linux From Scratch" {
	savedefault
	insmod ext2
	set root='(hd1,1)'
        linux   /vmlinuz root=/dev/sdb1 ro quiet splash 1
}

Ran 'sudo update-grub' and got this returned.

Code:

Generating grub configuration file ...
Found theme: /boot/grub/themes/poly-light-master/theme.txt
Found linux image: /boot/vmlinuz-4.10.0-20-generic
Found initrd image: /boot/initrd.img-4.10.0-20-generic
Found linux image: /boot/vmlinuz-4.4.0-77-generic
Found initrd image: /boot/initrd.img-4.4.0-77-generic
Found linux image: /boot/vmlinuz-4.4.0-75-generic
Found initrd image: /boot/initrd.img-4.4.0-75-generic
Found linux image: /boot/vmlinuz-4.4.0-53-generic
Found initrd image: /boot/initrd.img-4.4.0-53-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done

sharky · 05-15-2017, 07:37 AM

Actually that did add the custom menu entry and I was able to boot into the other installation.

It promptly kernel panic'd and died on me but that another issue.

This issue is resolved.

Thanks for the help.

syg00 · 05-15-2017, 07:43 AM

Add your initrd.

sharky · 05-15-2017, 10:48 AM

Quote:

Originally Posted by syg00

Add your initrd.

That was it. Able to boot into the other installation now.

There should be a way to mark a thread as 'DOUBLE SOLVED'.

Forgot to mention that I also had to add /boot before my 'linux' and 'initrd' entries. Final menu entry looks like this.

Code:

menuentry "Linux From Scratch" {
	savedefault
	insmod ext2
	set root='(hd1,1)'
        linux   /boot/vmlinuz root=/dev/sdb1 ro quiet splash 1
        initrd  /boot/initrd.gz
}