I think that it would be extremely misleading to mention persistent memory on systems where it cannot be supported. That would be all 32-bit ISA as well as a few 64-bit ISA.
It think it should be fairly clear to users if the value is innodb-log-file-mmap=false or innodb-log-file-mmap=none. Users are already familiar with innodb-use-native-aio=false on all platforms that do not support it. I still feel strongly that having system variables that appear and disappear without external reasons is confusing to users, and this innodb-log-file-mmap is now the first system variable that has that behaviour. Sure, I can help test pmem support on various platforms. But it will never be 100% on all platforms, so this variable visibility needs to be addressed separately. Also, just to confirm, you recent work on pmem features means that pmem is still intended to be in MariaDB and the removal in https://github.com/MariaDB/server/commit/8e663f5e9041e8e0998c792bf8d0c297a8b... has been reverted? I was about to follow suite in Debian in https://salsa.debian.org/mariadb-team/mariadb-server/-/merge_requests/86 but I guess I should not anymore? - Otto