Modernizing kmscon

[Skyler Ferris]

    Hello,
    
    I am writing to see if the project is interested in using an updated
    version of kmscon. I ran across this information because I have
    started using kmscon as the main interface on my Guix machine, and
    ended up digging into it a bit. I am sending this email only because
    I think it is polite to offer information upstream, if you are not
    interested in this then I can keep everything locally without any
    problems. I am currently keeping the code in a separate repository,
    but if you are interested in it then I can add it to the Guix
    repository and send a patch. There are 3 areas I will discuss: the
    elogind dependency, updating to a more recent Aetf version, and some
    additional patches I wrote which you may or may not want.
    
    # elogind dependency
    
    As a result of the work I will discuss below, I noticed that the
    current version of kmscon does not actually have multi-seat support
    enabled, which can be seen in the log output on the CI platform (1):
    
  Miscellaneous Options:
                debug: yes (yes: )
        optimizations: yes (yes: )
           multi-seat: no (no: libsystemd)
    
    Although, there is a different line farther up in the file
    indicating that multi-seat support is desired. I assume that this
    does not cause any practical issues because a cursory search of the
    issue tracker doesn't show anyone discussing it.  But the
    substitute* snippets changing the systemd dependency to an elogind
    dependency imply that someone wanted this at some point, so I'm
    mentioning it in case it's relevant. I tried building the tip of
    Aetf's tree with multi-seat support enabled and some changes based
    on the substitute* snippets. However, there was a fatal error when
    kmscon called `sd_login_monitor_new`. I don't know why this happened
    and I didn't look into it because I don't need multi-seat support
    and I don't have multi-seat equipment in any case.
    
    # Aetf version
    
    The current kmscon package uses the Aetf repository as the source,
    with a note that the old one is unmaintained. However, the commit
    that is specified is from the old repository. This means that Aetf's
    improvements, such as the ability to select a color palette, are not
    available. The package definition needs to use the
    meson-build-system and there are some new or updated dependencies
    (2). It seems to work on my machine, but currently kmscon is used in
    the installer where stability is critical so that users have a good
    first experience. So it might make sense to have a separate kmscon
    package with the updates and a keep the current package for the
    installer. I don't know how widely Aetf's version has been used, and
    it turns out that the automated test suite does very little (there
    are several files meant for interactive testing, but `meson test`
    only runs one test which checks some string parsing logic).
    
    # Additional patches
    
    I have 3 patches implementing 2 changes in my personal fork (3). The
    first change adds command-line options to set the desired width and
    height of the viewport. I added this because running kmscon in my VM
    did not fill the available space. This is implemented across 2
    commits, but I could squash them into one patch if you want it. I
    was careful to preserve existing behavior if these options are not
    specified so it should not cause any regressions. However, I don't
    know if you want to keep a patch that adds a feature in your
    repository. Most of the patches I've seen have been about
    compatibility with Guix, not adding new features. I did open a pull
    request with the upstream repository, but I do not think it is
    maintained any more. The most recent commit is from last year, and
    there are pull requests more than 6 months old which have not
    received any reply from the developer.
    
    I expect that you will want the other change if you want the updated
    kmscon. There were some warnings emitted by the current version of
    meson about deprecated functionality in the build files, I just
    changed it to conform to the new version. This did not require any
    functional changes. It just makes the build log a little bit
    quieter, which is generally a good thing.
    
    Sincerely,
    Skyler
    
    (1)  http://ci.guix.gnu.org/build/1396560/log/raw
    (2)
https://git.sr.ht/~skyvine/personal-code/tree/c525f74c64b27a793aca088489d7c9cfe7090581/item/src/scheme/guile/guix/packages.scm#L81
    (3) https://git.sr.ht/~skyvine/kmscon/log