Hello! I've spent quite a lot of effort in trying to get MariaDB work on all Debian architectures and I am happy to state that the situation visible at https://buildd.debian.org/status/package.php?p=mariadb is pretty good today. The only remaining problematic ones are hppa and Hurd.
Are there any Hurd porters with an interest in getting MariaDB working in the port? I am happy to take your patches, do additional testing and do uploads. Unfortunately I can't do the actual port fixing myself as there is too much work and the domain is something I am not strong in. My attempt at fixes at https://salsa.debian.org/mariadb-team/mariadb-server/-/merge_requests/145 did get some progress, so if you want to take on this challenge, you don't need to start from zero. I also have good experiences of getting upstream to accept porting related patches (e.g. https://github.com/MariaDB/server/pull/4480) so if you fix this in Debian and submit patches upstream, you most likely will get those fixes into MariaDB permanently for all users globally.
