Install debian package after unlocked Ostree

after unlocking ostree, why the repository can’t fetch updates from Endless repo? does endless repo have similar packages from Debian / Ubuntu repository? Do we need to add the apt-key and sign manually for EOS repository?

after unlocked, add Debian/ubuntu repository work but I’m afraid that will break all the EOS packaging dependencies

even when I tried to install the ubuntu package manual got below errors:

$ sudo dpkg -i v4l2loopback-utils_0.12.5-1ubuntu3_all.deb
dpkg-deb: error: archive ‘v4l2loopback-utils_0.12.5-1ubuntu3_all.deb’ uses unknown compression for member ‘control.tar.zst’, giving up
dpkg: error processing archive v4l2loopback-utils_0.12.5-1ubuntu3_all.deb (–install):
dpkg-deb --control subprocess returned error exit status 2
Errors were encountered while processing:
v4l2loopback-utils_0.12.5-1ubuntu3_all.deb

but when I added the ubuntu repository, and try to install that package, it calls all the necessary dependencies and I stopped there because I don’t want to break the EOS if I continue using ubuntu repository.

Our purpose of unlocking the ostree is to try out the printer or scanner that have released a driver for debian/ubuntu and some other thing like the v4l2loopback for webcam.

from Developers & technicians | Endless OS Support Site there is not enough information to be EOS developer other than testing beta and latest development.

after unlocking ostree, why the repository can’t fetch updates from Endless repo?

Unlocking the ostree is unsupported, but OK for experimentation if you’re happy to deal with any irreversible breakage. However it’s not possible to advise further if you don’t provide more details (what commands did you use, what results did you expect, what results did you observe, which OS version are you running, etc).

after unlocked, add Debian/ubuntu repository work but I’m afraid that will break all the EOS packaging dependencies

Yes, deviation away from Endless’s debian base is likely to be problematic, but you’ll likely be OK if you stick to the same Debian base (e.g. you can use Debian bullseye with eos4 likely without too many difficulties; eos-enable-debian-apt is another unsupported-but-potentially-useful tool)

dpkg-deb: error: archive ‘v4l2loopback-utils_0.12.5-1ubuntu3_all.deb’ uses unknown compression for member ‘control.tar.zst’, giving up

Looks like the package you are using is not compatible with the version of apt that is present on your installation. I imagine the same would happen if you took an old version of Ubuntu and tried to use brand new packages like this.

Our purpose of unlocking the ostree is to try out the printer or scanner that have released a driver for debian/ubuntu and some other thing like the v4l2loopback for webcam.

Which printer/scanner (& associated driver) are you trying to test here? If there is support in official Debian/Ubuntu then we may be able to include it in official releases. Your idea to use Debian packages as a one-off experiment is sensible but only if you align the Debian version used by Endless with the Debian version that the package is built for.

Building external kernel modules such as v4l2loopback is likely much harder; feel free to try but I would expect this to bring up several challenges on the way.

thanks @Daniel for a very thorough explanation.

So does basically eos has all the bullseyes packages or eos4 is mixed between eos and bulleyes repo?

eos3, eos4, and eos5 are based on bullseye, right?

As for the printer/scanner, what I meant is the manufacturer release a deb installer for their printer (from the manufacturer support portal) and not from the official debian/ubuntu repository.

so if I want to have v4l2loopback in eos, which is the best way moving forward? request the eos dev to include it in future releases/milestones or I can just install it from bullseye repo? this virtual webcam is requested to use the blurred or replace background on webcam session, e.g: BBB, zoom and etc

EOS-3.x varies depending which release you are asking about. EOS-3.9 is based on Debian Buster.

At this point I would suggest focusing your efforts on EOS-4 as it will be released soon and is much closer to Debian than before. It is based on Debian Bullseye. Most of the packages come from Debian Bullseye directly, but a small number of them are overridden and modified by Endless (apt repo is based at https://deb.endlessos.org/).

EOS-4 does include a major update to the printer/scanner support, so you might want to double check your device there if you haven’t already. We are now focusing our support on those printers and scanners that support driverless standards (i.e. printers and scanners that can be used with a smartphone).

If your device does still require a funky package direct from the manufacturer then that’s not something we support officially, but you’re welcome to open things up and try it on your end - in which case you’d want a deb package compatible with Debian Bullseye.

v4l2loopback is much harder since it is a kernel driver and unlike installing extra deb packages, that’s more unchartered territory. The best “moving forward” answer there would be to have it included in the official Linux kernel, then it will become available in Endless (& all other distros) without any installation process. I think that’s unlikely though, since v4l2loopback being on the kernel side doesn’t seem to be an optimal solution for solving that problem. Instead I would expect this functionality to be introduced in userspace via PipeWire at some point going forward. (Endless will adopt PipeWire along with Debian in due course)

This thread is a good reminder that we should update this message from eos-dev-unlock:

wjt@camille:~$ eos-dev-unlock 
This script uses "ostree admin unlock" to create a writable /usr
overlay, and makes some other basic tweaks so that apt works in this
setup. By default, the changes made to the overlay will be lost on
reboot; passing --hotfix will make the changes persist across 
reboot, and clone the current deployment as the rollback deployment.

WARNING: If you're not an Endless developer you will not be able to
meaningfully use apt.

Are you sure you want to proceed? [y/N] 

The second paragraph is not quite true any more – our apt repos are now public.