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mirrortokyo

Member

Registered: 2021-04-08

Posts: 45  

Re: merged /usr

It's helpful to know what is different in your dmesg output compared with booting before usrmerge.

I had enough "fun" with incrementally adding symbolic links from old locations within /bin /lib /sbin to where the new locations in /usr/bin /usr/lib and /usr/sbin as individula packages changed the location of their files and finally installing the usrmerge package after I had manually done all the work.

Unfortunately when there are a lot of changes in one hit, it is difficult to identify the specific changes/errors that broke things.

TheLancashireman

Member

Registered: 2019-07-01

Posts: 13  

Re: merged /usr

I can't get the dmesg output for the last known good case, but I can extract the information from syslog. It'll take a while though.

In the cases where the kernel doesn't find the root fs there's no dmesg and no log, of course.

I just tried transplanting the kernel files (config-, initrd.img-, System.map- and vmlinuz-6.5.0-4-amd) from my laptop. Also ceres, but not updated for a while. I never had 6.5.0-4 on my desktop so I wouldn't expect it to work properly (missing modules) but in fact it works almost as well as the setup with the forced modules in the initrd. With that in mind, I can switch back to a boot set from an earlier kernel (probably 6.1.xxx). I still have those kernels installed, but all the initrd files in /boot have been polluted by mkinitramfs. Fortunately I made a backup before I started fiddling :-)

One more "interesting" fact: my work laptop runs debian sid/unstable. A couple of updates ago it appeared to stop booting at the point where the text display switches from 80x25 to high-res. In fact, it didn't stop booting - it was the console that didn't work. An older kernel worked fine, so I uninstalled the generic kernel package and nailed the kernel version at 6.1.27-1. Now that I look at the fs more closely, it has been usrmerged - /bin, /sbin etc. are symlinks. So maybe my trouble there was an early indication of usrmerge trouble. I'm leaving the company at the end of March, so I won't do any more updates in case they break something.

Last edited by TheLancashireman (2024-02-26 15:27:51)

TheLancashireman

Member

Registered: 2019-07-01

Posts: 13  

Re: merged /usr

First inkling of a problem:  https://bugs.devuan.org/cgi/bugreport.cgi?bug=828

That was before usrmerge was forced. Some scripts had hard-coded paths to /bin and /sbin, but the programs they use moved to /usr/bin and /usr/sbin

But the problem of hard-coded paths should go away after usrmerge, shouldn't it?

Last edited by TheLancashireman (2024-02-26 16:47:42)

golinux

Administrator

Registered: 2016-11-25

Posts: 3,153  

Re: merged /usr

That depends on how and when the merge is activated as well as the non-standard choices made by the user prior to the merge. Please see this usrmerge announcement posted a few days ago.

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TheLancashireman

Member

Registered: 2019-07-01

Posts: 13  

Re: merged /usr

The non-standard choices that I made earlier were:
* adding modprobe, lsmod & co as symlinks to kmod
* editing some shellscripts to add /usr/bin and /usr/sbin to the hard coded paths at the top

Anyway, FWIW the logs are here: https://experimental.thelancashireman.org/devuan-logs/
There's a description file (info.txt)

TheLancashireman

Member

Registered: 2019-07-01

Posts: 13  

Re: merged /usr

I've found a solution or a workaround: downgraded to eudev_3.2.12-4+deb11u1_amd64.deb and libeudev1_3.2.12-4+deb11u1_amd64.deb
Removed my hacked list of modules from /etc/initramfs-tools/modules and ran update-initramfs -u

Now my system boots kernel 6.6.15 correctly. Keyboard and mouse both working. At some point I should tidy up /boot again and regenerate all the initrd.img files

So it might not be related to usrmerge after all.

What now? Should I report a bug against eudev?

Last edited by TheLancashireman (2024-02-26 20:44:28)

mirrortokyo

Member

Registered: 2021-04-08

Posts: 45  

Re: merged /usr

Unpacking dpkg (1.22.5) over (1.22.4) ...
Setting up dpkg (1.22.5) ...
dpkg: warning: This system uses merged-usr-via-aliased-dirs, going behind dpkg's
dpkg: warning: back, breaking its core assumptions. This can cause silent file
dpkg: warning: overwrites and disappearances, and its general tools misbehavior.
dpkg: warning: See <https://wiki.debian.org/Teams/Dpkg/FAQ#broken-usrmerge>.

But the self-contradiction continues:

Q: Does dpkg support merged-/usr-via-aliased-dirs?
A: No. This approach is considered broken by design and breaks many common expectations.

In dpkg the expected breakage includes:

failing to notice file conflicts with the subsequent silent file overwrites by f.ex. dpkg, dpkg-divert and update-alternatives,

files disappearing during package upgrades or diversion installation,
failing to activate triggers on pathnames,
failing to find pathnames on dpkg-query -S searches,

failing to install packages shipping the same filename in real and aliased directories (with rather cryptic errors), f.ex. to be able to install otherwise dependency satisfiable packages needed by old software,
completely messing up the filesystem by simply using dpkg-deb -x or tar -x.

If you have a system that has been installed recently (since Debian buster) or switched via the usrmerge hack, you might want to consider using the dpkg-fsys-usrunmess program (but beware that it should not be used in systemd's emergency mode) or reinstalling. For further information see Teams/Dpkg/MergedUsr.

Debian officially only supports merged-/usr-via-aliased-dirs systems. Converting to an unmerged-/usr setup might break the system in unexpected ways in the future, including data loss or failure to boot.

boughtonp

Member

From: UK

Registered: 2023-01-19

Posts: 206  

Website

Re: merged /usr

See //sources.debian.org/src/dpkg/1.22.5/debian/dpkg.postinst/

Presumably the Devuan vendor value is not "debian", and someone needs to do what Kali have done and submit a patch.

Last edited by boughtonp (2024-02-27 16:21:49)

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TheLancashireman

Member

Registered: 2019-07-01

Posts: 13  

Re: merged /usr

For what it's worth - just ran apt-update and noticed new versions of eudev and libeudev1 incoming. After upgrading them (and only them) PC boots with no problems.
Then did a full upgrade. Now cryptsetup is causing trouble, but that's a different matter.

I got the warning from dpkg too, and a few warnings about dependency problems during the upgrade.

Last edited by TheLancashireman (2024-02-28 18:00:23)