Only libraries optimized for the running system end up in initramfs

[Balint Reczey]

... that may prevent rebooting to systems without the same optimization.

This can be observed by on EC2 m6g instances:

$ sudo apt install libc6-lse
$ sudo update-initramfs -k all -u
$ unmkinitramfs /boot/initrd.img i
$ ls i/
bin conf cryptroot etc init lib run sbin scripts usr var
$ cd i/
$ find . -name *pthread*
./usr/lib/aarch64-linux-gnu/atomics/libpthread.so.0
./usr/lib/aarch64-linux-gnu/atomics/libpthread-2.31.so

Luckily btrfs-progs does not play a role in rebooting, thus m6g instances can still be resized to a1 instance types, and I observed no failure when trying to do so.

Follow-up for LP: #1880853.

[Balint Reczey (rbalint)]

Since the m6g-> a1 resizes are IMO not likely when also using btrfs I'm marking this bug as low.