What directories should be read/write on an immutable system?

[knotty rover]

This isnt exactly a vanillaOS specific question, but since ABroot was developed here i thing it would be the best spot to create this question. Question is the title. Right now im thinking just /etc, /var, and /home are enough to be rw and everything else can be ro, but what do u guys think?

[foggy karma]

Packages? You meant directory?

[knotty rover]

Oh yeah typo my mistake

What directories should be read/write on an immutable system?

[foggy karma]

/var i think is more of a matter of opinion. I think there are several immutable Linux distro where /var isn't mutable.

[wicked field]

/tmp needs to be read-write too

[knotty rover]

Good catch. I think i will make /tmp use tmpfs.

[knotty rover]

Most package managers break when /var is not mutable lol

Also need /var/log.

[wicked field]

/var/log my behated

i almost broke my install getting a backtrace that saved there

[knotty rover]

And a lot of apps like to play with /var too like virtualization services and such so 😅

[knotty rover]

What how

Just random stack trace?

Fucky kernel or what

[wicked field]

i tried to get a backtrace for webkit

but that shit can take like 20+ GB for some reason

[knotty rover]

Jeez 20 gigs of just logs 💀

[young kettle]

Also the themes folder under usr

[foggy karma]

Which DE is this necessary for? Even for KDE, it's only really needed for SDDM themes and plymouth themes. Both of which I don't consider to be necessary and people should layer it themselves instead of something that is supported by default.

[latent iron]

/usr should be mutable in any case, otherwise being immutable would be joke.

[foggy karma]

I think he just meant that /usr/share/themes be writable (aside from /usr/share/themes/default or any equivalent in other DEs)

[wintry swift]

/usr/share/themes shouldn't be mutable

there's no point, just use ~/.local/share/themes

[wintry swift]

/tmp, /dev, /sys, /proc, /var, /home, /etc

[latent iron]

KDE settings change the sddm theme in /usr.

[foggy karma]

they also added plymouth recently

[foggy karma]

but yeah, I think this has been discussed between Kinoite and KDE devs -- there seems to be interest in changing it, but I'm not sure how likely it is to change. We'll see if they'll change it for Plasma 6.

[wintry swift]

but not /usr/share/themes

[knotty rover]

Why would /dev /sys or /proc matter? Theyre not real files

Ie: there is no reading or writing done to the underlying FS. Meaning it wouldnt matter if its ro or not.

[wintry swift]

there's a lot of writing happening to /dev

[knotty rover]

Like what? None of my mutable distros have anything saved in /dev post shutdown

[latent iron]

I am not sure but for example if someone wants to create a bootable pen drive, /dev/sdX need to be mutable, doesn't it?

[wintry swift]

just because there's nothing saved, doesn't mean nothing is written there

the framebuffer is in /dev, that has to be written somehow

[knotty rover]

That doesnt interact with the filesystem tho. Even while immutable /dev is populated with stuff and can be interacted with.

Im fairly certain that the kernel mounts it as a ramdisk so.

[knotty rover]

As i was stating to xenia, its a virtual filesystem. So when u write to /dev/sdX you arent reading data from the btrfs fs that holds /dev but rather directly interacting with the device thru that /dev/sdX file.

[wintry swift]

yes, which is why you have to make sure stuff can be written there

I don't think mounting to an immutable directory works

[knotty rover]

Makes no difference

Tried it already as mentioned before

the underlying filesystem doesnt matter here since its a ramdisk. Its being “overlayed”.