Can I remove *.old-dkms files

Question

I've had a problem with installing kernels, because my /boot partition is very small (about 200+ MB) (and I can't expand because I'm using lvm).

Listing the files inside /boot, I have:

defaultuser@theoriginalpc:~$ ls -lahS /boot
totalo 128M
-rw-r--r--  1 root root  38M Dec 22 14:33 initrd.img-4.4.0-57-generic
-rw-r--r--  1 root root  38M Dec 22 13:12 initrd.img-4.4.0-47-generic.old-dkms
-rw-r--r--  1 root root  17M Dec 22 14:27 initrd.img-4.4.0-57-generic.old-dkms
-rw-r--r--  1 root root  14M Dec 22 14:33 initrd.img-4.4.0-53-generic.old-dkms
-rw-r--r--  1 root root  10M Dec 22 13:13 initrd.img-4.4.0-47-generic
-rw-------  1 root root 6.8M Dec 10 12:04 vmlinuz-4.4.0-57-generic
-rw-------  1 root root 3.7M Dec 10 12:04 System.map-4.4.0-57-generic
-rw-r--r--  1 root root 1.2M Dec 10 12:04 abi-4.4.0-57-generic
-rw-r--r--  1 root root 186K Dec 10 12:04 config-4.4.0-57-generic
-rw-r--r--  1 root root 181K Jan 28  2016 memtest86+_multiboot.bin
-rw-r--r--  1 root root 181K Jan 28  2016 memtest86+.elf
-rw-r--r--  1 root root 179K Jan 28  2016 memtest86+.bin
drwx------  2 root root  12K Nov 18 15:06 lost+found
drwxr-xr-x 25 root root 4.0K Dec 22 14:33 ..
drwxr-xr-x  4 root root 1.0K Dec 22 14:33 .
drwxr-xr-x  6 root root 1.0K Dec 22 14:34 grub

I see that the *.old-dkms files are taking up a lot of space.

Is it okay to remove them?

(Here's the data when ran sudo update-grub)

Generating grub configuration file ...
Averto: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-57-generic
Found initrd image: /boot/initrd.img-4.4.0-57-generic
Found memtest86+ image: /memtest86+.elf
Found memtest86+ image: /memtest86+.bin
farita

Answer 1

You can safely remove them.

When DKMS builds a module for the kernel, it can also include it in the initramfs (the initrd files you see in /boot). Before doing so, it does a backup of the current initramfs, adding .old-dkms at the end of the file.

So, unless DKMS crashes while generating the initramfs (quite unlikely), the .old-dkms are of no use afterwards.

If you are a bit paranoid, you should first reboot the machine to verify the kernel and the newly generated initramfs work well, and the remove the .old-dkms.