Improve boot experience: time, screen content (linux parts) (WIP issue)

[m-weigand]

Boot time

Currently the Pinenote boots in ca. one 1 Minute (e.g., see https://github.com/m-weigand/mw_pinenote_misc/raw/main/videos/20240830_pn_boot_plymouth_small.mp4)

20240830_pn_boot_plymouth_small.mp4

1:	Debian GNU/Linux trixie/sid 6.9.0-pinenote-202407091753-gc07ecb4d29c8
Retrieving file: /boot/initrd.img-6.9.0-pinenote-202407091753-gc07ecb4d29c8
15055737 bytes read in 12338 ms (1.2 MiB/s)
Retrieving file: /boot/vmlinuz-6.9.0-pinenote-202407091753-gc07ecb4d29c8
22618624 bytes read in 285 ms (75.7 MiB/s)

Potential ways to improve

• Reduce kernel/initrd sizes
• Currently we do not have the capability to load compressed kernels
• Optimise user-space (mutter takes ages to load)

Splash screen/plymouth

• [ ] known bug: the pinenote plymouth theme shows white text on a mostly-white background -> for example, we do not see any messages when package updates are installed!

Boot splashs were optimized a bit, see, e.g.:

http://pinenote.mweigand.net/20241011_pn_first_boot_small.mp4