update-grub does not add all kernels to the grub menu

Question

Ubuntu 21.10.

I am building kernels as documented at https://help.ubuntu.com/community/Kernel/Compile and https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel.

DEB_BUILD_OPTIONS=parallel=$(getconf _NPROCESSORS_ONLN) AUTOBUILD=1 NOEXTRAS=1 \
    fakeroot debian/rules binary-arch

This compilation command has the same result:

make --jobs=$(getconf _NPROCESSORS_ONLN) bindeb-pkg \
    LOCALVERSION=-custom-$(git describe | tr '[:upper:]' '[:lower:]')

This creates some .deb packages:

$ ls -hal ../*.deb
-rw-r--r-- 1 amedee amedee 8,2M feb 26 02:17 ../linux-headers-5.13.19-ubuntu-5.13.0-22.22_5.13.19-ubuntu-5.13.0-22.22-6_amd64.deb
-rw-r--r-- 1 amedee amedee  70M feb 26 02:18 ../linux-image-5.13.19-ubuntu-5.13.0-22.22_5.13.19-ubuntu-5.13.0-22.22-6_amd64.deb
-rw-r--r-- 1 amedee amedee 1,2M feb 26 02:17 ../linux-libc-dev_5.13.19-ubuntu-5.13.0-22.22-6_amd64.deb

I install them like this:

sudo dpkg --install \
    ../linux-headers-5.13.19-ubuntu-5.13.0-22.22_5.13.19-ubuntu-5.13.0-22.22-6_amd64.deb \
    ../linux-image-5.13.19-ubuntu-5.13.0-22.22_5.13.19-ubuntu-5.13.0-22.22-6_amd64.deb

This is then the content of /boot:

$ ls -hal /boot/*5.13*
-rw-r--r-- 1 root root 252K nov  5 10:21 /boot/config-5.13.0-22-generic
-rw-r--r-- 1 root root 251K feb 26 02:15 /boot/config-5.13.19-ubuntu-5.13.0-22.22
-rw-r--r-- 1 root root  40M feb 22 16:21 /boot/initrd.img-5.13.0-22-generic
-rw-r--r-- 1 root root  37M feb 26 02:20 /boot/initrd.img-5.13.19-ubuntu-5.13.0-22.22
-rw------- 1 root root 5,7M nov  5 10:21 /boot/System.map-5.13.0-22-generic
-rw-r--r-- 1 root root 5,6M feb 26 02:15 /boot/System.map-5.13.19-ubuntu-5.13.0-22.22
-rw------- 1 root root 9,8M nov  5 13:51 /boot/vmlinuz-5.13.0-22-generic
-rw-r--r-- 1 root root 8,5M feb 26 02:15 /boot/vmlinuz-5.13.19-ubuntu-5.13.0-22.22

Update initramfs (which strictly speaking isn't necessary because that has already been done, but for good measure):

$ sudo update-initramfs -u -k all
update-initramfs: Generating /boot/initrd.img-5.13.19-ubuntu-5.13.0-22.22
update-initramfs: Generating /boot/initrd.img-5.13.0-22-generic

Then I run update-grub:

amedee@kerbol:~/repos/ubuntu-impish$ sudo update-grub
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.13.0-22-generic
Found initrd image: /boot/initrd.img-5.13.0-22-generic
Found linux image: /boot/vmlinuz-5.13.0-22-generic
Found initrd image: /boot/initrd.img-5.13.0-22-generic
Adding boot menu entry for UEFI Firmware Settings
done

My compiled kernel 5.13.19-ubuntu-5.13.0-22.22 is not added to the Grub menu by update-grub. I know I can add it manually, but that has a risk of typos. I also need to compile a lot of kernels because I'm trying to locate a possible bug using git bisect. The kernel issue that I'm troubleshooting does not occur in more recent mainline kernels, only in (some, but not all) Ubuntu 21.10 kernels, so I only do this to learn something and to satisfy my curiosity.

What do I need to do so that update-grub adds my compiled kernel from the /boot directory to the Grub menu?

Amedee Van Gasse · Accepted Answer · 2022-03-01T10:30:06.193

The following three commands solve this problem, by turning off the executable bit on 09_lowlatency and turning on the bit for 10_linux, in accordance with the text in /etc/grub.d/README.lowlatency.

# chmod -x /etc/grub.d/09_lowlatency
# chmod +x /etc/grub.d/10_linux
# update-grub

Solution found at https://askubuntu.com/a/1228269/149519.

To confirm that it now works as expected:

$ ls -hal /boot ; echo ; sudo update-grub
total 107M
drwxr-xr-x  4 root root 4,0K feb 28 04:42 .
drwxr-xr-x 20 root root 4,0K feb 26 01:13 ..
-rw-r--r--  1 root root 252K nov  5 10:21 config-5.13.0-22-generic
-rw-r--r--  1 root root 251K feb 26 02:15 config-5.13.19-ubuntu-5.13.0-22.22
drwx------  4 root root 4,0K jan  1  1970 efi
drwxr-xr-x  5 root root 4,0K feb 28 04:42 grub
lrwxrwxrwx  1 root root   28 feb 28 04:26 initrd.img -> initrd.img-5.13.0-22-generic
-rw-r--r--  1 root root  40M feb 26 13:55 initrd.img-5.13.0-22-generic
-rw-r--r--  1 root root  37M feb 26 13:54 initrd.img-5.13.19-ubuntu-5.13.0-22.22
-rw-------  1 root root 5,7M nov  5 10:21 System.map-5.13.0-22-generic
-rw-r--r--  1 root root 5,6M feb 26 02:15 System.map-5.13.19-ubuntu-5.13.0-22.22
lrwxrwxrwx  1 root root   25 feb 28 04:27 vmlinuz -> vmlinuz-5.13.0-22-generic
-rw-------  1 root root 9,8M nov  5 13:51 vmlinuz-5.13.0-22-generic
-rw-r--r--  1 root root 8,5M feb 26 02:15 vmlinuz-5.13.19-ubuntu-5.13.0-22.22
Sourcing file /etc/default/grub' Sourcing file/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.13.19-ubuntu-5.13.0-22.22
Found initrd image: /boot/initrd.img-5.13.19-ubuntu-5.13.0-22.22
Found linux image: /boot/vmlinuz-5.13.0-22-generic
Found initrd image: /boot/initrd.img-5.13.0-22-generic
Adding boot menu entry for UEFI Firmware Settings
done

update-grub does not add all kernels to the grub menu

1 Answers1