[systemd-devel] Support for unmerged-usr systems will be REMOVED in the second half of 2023

[Luca Boccassi]

On Wed, 2022-10-26 at 11:39 +0100, Richard Purdie wrote:
> On Tue, 2022-09-20 at 19:18 +0000, Luca Boccassi wrote:
> > Hello,
> > 
> > Following this thread started back in April:
> > 
> > https://lists.freedesktop.org/archives/systemd-devel/2022-April/047673.html
> > 
> > As far as we understand there are no distributions running or
> > optionally supporting systemd that have not either completed, or at
> > least started, the transition to merged-usr systems.
> 
> For the record and to be really clear, Yocto Project has systemd
> support but also supports arbitrary filesystem layout. We have not
> planned or agreed to drop that filesystem layout configuration/support.
> It is actively used today by our user base today, perfectly fine.
> 
> The statement above is therefore misleading as there are distributions
> out there which have not even agreed to the change and are not planning
> a transition.
> 
> I was asked by Luca to test the "usr-merge" config with systemd and it
> failed in our CI, which is sadly what I suspected would happen. It
> takes time in itself to even queue up these kinds of tests and process
> the results. I did this several months ago and have seen no interest or
> help in fixing the result.
> 
> This change from systemd effectively mandates we change our
> configuration to match what systemd dictates and only support that. I
> don't like what that represents and don't consider it a positive
> development.

Also for the record, Yocto has had (configurable) support for merged-
usr for a long time, and we've been using it in production at $work for
3+ years without any issue. Also, Yocto supports many many
configuration options, and they are definitely not all compatible with
each other - there are conflicts and dependencies, as it is natural, so
adding a systemd -> usrmerge dependency seems technically workable and
conceptually reasonable, and it's not that different from other
requirements and dependencies that are already there. You don't have to
switch !systemd builds, if you don't want to, even if it would be a
good idea of course. You still have one year (on top of the ~10 years
since this has been a done thing) to fix/skip/drop those faulty unit
tests.

I mean, the fact that the Yocto-supported usrmerge option is not
compatible with Yocto-internal unit tests is hardly our fault, no? From
my point of view it really sounds like you have too many options and
not enough QA resources to cover all configurable combinations
effectively. It almost seems like dropping some of those variations,
say those which provide no technical value for example, might be a good
idea to focus QA resources and improve overall quality ;-) Of course
it's your distro, so you are perfectly entitled to do as you see fit.

Sorry to disappoint, but we will certainly not delay yet again because
of fixable unit test issues in one downstream distro. At this point
merged-usr is table stakes and the basis for so many things to build on
top, that it is just not reasonable anymore for us to support not
having it in 2023, more than 10 years after it was introduced.

-- 
Kind regards,
Luca Boccassi
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