[SOLVED] [slackware novice] setting generic kernel for grub2

gnus · 07-02-2016, 12:55 PM

Hi, I read this post - Switch to a generic kernel. Most of the documentation is for Lilo bootloader. I couldn't see any official help on setting generic kernel using grub-mkconfig. Can you please give me to detail steps of setting generic kernel for grub bootloader(or link to it)?

[ I tried to resolve this by seeing few threads. However, they were having different errors.
I created initrd.gz by following steps in docs.slackware.com. Added its entry in /etc/grub.d/40_custom. When I selected this entry from boot menu, I got error '/boot/initrd.gz not found'. I recently installed 14.1. I am new to Slackware. As 14.2 is released and I haven't done much on currently installed OS, I would move to 14.2. However, I think these errors will be in 14.2 too. I think, these are not errors, but I am missing something while achieving this]

Richard Cranium · 07-02-2016, 02:22 PM

OK, how is your system set up?

In my case(s) (I run grub2 on multiple machines), I have a boot partition that is formatted ext2. Everything else is in an LVM logical volume, although you don't have to use LVM.

Code:

root@hp635:~# fdisk -l /dev/sda
Disk /dev/sda: 232.9 GiB, 250059350016 bytes, 488397168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 44C7FDC9-555A-41DF-88B0-B29E0DE2285D

Device       Start       End   Sectors   Size Type
/dev/sda1     2048   1050623   1048576   512M Linux filesystem
/dev/sda2  1050624 488397134 487346511 232.4G Linux LVM
root@hp635:~# cat /etc/fstab
/dev/cryptvg/swaplv swap             swap        defaults         0   0
/dev/cryptvg/rootlv /                ext4        defaults         1   1
/dev/sda1        /boot            ext2        defaults         1   2
/dev/cryptvg/homelv /home            jfs       defaults         1   2
/dev/cryptvg/optlv /opt             ext4        defaults         1   2
/dev/cryptvg/tmplv /tmp             ext4        defaults         1   2
/dev/cryptvg/usrlv /usr             ext4        defaults         1   2
/dev/cryptvg/varlv /var             ext4        defaults         1   2
/dev/cryptvg/varloglv /var/log         ext4        defaults         1   2
/dev/cryptvg/usrlocallv /usr/local ext4       defaults,journal_async_commit 1 2
#/dev/cdrom      /mnt/cdrom       auto        noauto,owner,ro,comment=x-gvfs-show 0   0
/dev/fd0         /mnt/floppy      auto        noauto,owner     0   0
devpts           /dev/pts         devpts      gid=5,mode=620   0   0
proc             /proc            proc        defaults         0   0
tmpfs            /dev/shm         tmpfs       defaults         0   0

mralk3 · 07-02-2016, 05:11 PM

You can find information about installing grub during Slackware installation here.

Are you using UEFI hardware? If so, please look at this.

There is also the documentation for grub located on your system at: /usr/share/doc/grub-2.00. The INSTALL text file is very helpful.

Hangaber · 07-02-2016, 11:16 PM

Quote:

Originally Posted by gnus

I created initrd.gz by following steps in docs.slackware.com. Added its entry in /etc/grub.d/40_custom. When I selected this entry from boot menu, I got error '/boot/initrd.gz not found'.

The answer to these two questions should help locate the culprit.
Unless your initrd.gz is named something else, you shouldn't need to modify /etc/grub.d/40_custom - what did you add in there?

Does the file exist: /boot/initrd.gz ?
If your /boot is on a different partition, make sure it's mounted already when you run the mkinitrd and grub-mkconfig commands.

If you created initrd.gz, and your generic kernel exists;

Backup your existing /boot/grub/grub.cfg and create a new grub.cfg with this command;

Code:

grub-mkconfig -o /boot/grub/grub.cfg

The output of this should list all kernels (and matching initrd's, if they exist)
For example, I named mine "vmlinuz-custom-<version>, so mine says;

Code:

Generating grub.cfg ...
Found linux image: /boot/vmlinuz-custom-4.4.14
Found initrd image: /boot/initrd-custom-4.4.14.gz
Found linux image: /boot/vmlinuz-custom-4.1.27
Found initrd image: /boot/initrd-custom-4.1.27.gz

Note: Because I have a custom filename, I did have to tweak 40_custom so that the script knows what pattern to look for. If yours is just called initrd.gz then that will be found automatically.

Richard Cranium · 07-03-2016, 12:58 AM

Stock /etc/grub.d/40_custom doesn't have anything that would generate a menu entry in it.

Code:

root@testbed:~# cat /etc/grub.d/40_custom 
#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
root@testbed:~#

gnus · 07-03-2016, 09:46 AM

Quote:

Originally Posted by Richard Cranium

OK, how is your system set up?

My boot partition has ext4 filesystem. It looks as following. Should it be ext2?

Code:

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x5b7f48cf

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048   318048255   159023104    7  HPFS/NTFS/exFAT
/dev/sda2       318048256   318560255      256000   83  Linux
/dev/sda3       318560256   326948863     4194304   82  Linux swap
/dev/sda4       326948864   625142447   149096792   83  Linux

Quote:

Originally Posted by Hangaber

The answer to these two questions should help locate the culprit.
Unless your initrd.gz is named something else, you shouldn't need to modify /etc/grub.d/40_custom - what did you add in there?
................
Does the file exist: /boot/initrd.gz ?
If your /boot is on a different partition, make sure it's mounted already when you run the mkinitrd and grub-mkconfig commands.

If you created initrd.gz, and your generic kernel exists;

Backup your existing /boot/grub/grub.cfg and create a new grub.cfg with this command;

Code:

grub-mkconfig -o /boot/grub/grub.cfg

The output of this should list all kernels (and matching initrd's, if they exist)
For example, I named mine "vmlinuz-custom-<version>, so mine says;

Code:

Generating grub.cfg ...
Found linux image: /boot/vmlinuz-custom-4.4.14
Found initrd image: /boot/initrd-custom-4.4.14.gz
Found linux image: /boot/vmlinuz-custom-4.1.27
Found initrd image: /boot/initrd-custom-4.1.27.gz

Note: Because I have a custom filename, I did have to tweak 40_custom so that the script knows what pattern to look for. If yours is just called initrd.gz then that will be found automatically.

I have following kernels and initrds in boot folder.

Code:

-rw-r--r--  1 root root 4579269 Jul  3 00:07 initrd-generic-3.10.17
drwxr-xr-x 14 root root    1024 Jul  3 00:07 initrd-tree
lrwxrwxrwx  1 root root      20 Jul  2 01:12 vmlinuz -> vmlinuz-huge-3.10.17
-rw-r--r--  1 root root 3450176 Feb 15  2014 vmlinuz-generic-3.10.17
-rw-r--r--  1 root root 6436992 Feb 15  2014 vmlinuz-huge-3.10.17

I have renamed initrd.gz(which I have created using Slackware script mkinitrd_command_generator.sh) to initrd-generic-3.10.17. After this I ran 'grub-mkconfig -o /boot/grub/grub.cfg'. However, there isn't any change in grub.cfg. I don't see any entry about initrd.cfg

Richard Cranium · 07-03-2016, 11:12 AM

Could you post the contents of your /boot/grub/grub.cfg?

Hangaber · 07-03-2016, 11:33 AM

Quote:

Originally Posted by gnus

I have following kernels and initrds in boot folder.

Code:

-rw-r--r--  1 root root 4579269 Jul  3 00:07 initrd-generic-3.10.17
drwxr-xr-x 14 root root    1024 Jul  3 00:07 initrd-tree
lrwxrwxrwx  1 root root      20 Jul  2 01:12 vmlinuz -> vmlinuz-huge-3.10.17
-rw-r--r--  1 root root 3450176 Feb 15  2014 vmlinuz-generic-3.10.17
-rw-r--r--  1 root root 6436992 Feb 15  2014 vmlinuz-huge-3.10.17

I have renamed initrd.gz(which I have created using Slackware script mkinitrd_command_generator.sh) to initrd-generic-3.10.17. After this I ran 'grub-mkconfig -o /boot/grub/grub.cfg'. However, there isn't any change in grub.cfg. I don't see any entry about initrd.cfg

Either rename "initrd-generic-3.10.17" to "initrd.gz", or;

Edit file "/etc/grub.d/10_linux", and at about line 202, insert something like this;

Code:

"initrd-generic-${version}" \

(so it'll end up something like this...)

Code:

           "initramfs-genkernel-${GENKERNEL_ARCH}-${alt_version}" \
           "initrd-generic-${version}" \
           "initrd.gz"; do

...then run grub-mkconfig again.

Code:

grub-mkconfig -o /boot/grub/grub.cfg

gnus · 07-05-2016, 09:04 AM

Thanks Hangaber, Richard Cranium, mralk3. I have upgraded(clean install) to 14.2. This time I didn't face any issues while installing LILO. And I could set the generic kernel by following steps mentioned in Slackware Documentation. As I can't give more details of issue anymore, marking this one as 'Solved'. Thanks for your inputs.