Thanks for the tips, I relayed suggestion about GCC Compile Farm to upstream.
Also I noticed that the sparc64 crashes are pretty random, happening in different tests. Maybe the runner is unstable? For example in https://buildd.debian.org/status/fetch.php?pkg=mariadb&arch=sparc64&ver=1%3A11.8.1-4&stamp=1745481491&raw=0 the failing tests were: main.status main.vector2 main.query_cache main.set_statement_notembedded main.ssl_timeout main.log_state main.userstat main.backup_lock_binlog main.lock_multi main.xa In https://buildd.debian.org/status/fetch.php?pkg=mariadb&arch=sparc64&ver=1%3A11.8.1-4&stamp=1745449363&raw=0 the failing tests were: main.vector2 main.concurrent_innodb_safelog main.sp-innodb main.check