When migrating from MySQL 5.6 to MariaDB 10.0, one is likely to have gtid_mode=ON. Currently, this throws an error and MariaDB will not start.

Since MariaDB already recognizes so many other MySQL 5.6-specific variables, and only provides "[warning]s", then I think it should do the same for this variable.

For instance, here are a number of warnings:

140805 12:24:00 [Note] /usr/sbin/mysqld: Shutdown complete

140805 12:24:00 mysqld_safe mysqld from pid file /mysql/ppc/data/ppcdm-205.lhr4.prod.booking.com.pid ended
140805 12:52:04 mysqld_safe Starting mysqld_wrapper daemon with databases from /mysql/ppc/data
140805 12:52:17 [Warning] 'master-info-repository' is MySQL 5.6 compatible option. Not used or needed in MariaDB.
140805 12:52:17 [Warning] 'relay-log-info-repository' is MySQL 5.6 compatible option. Not used or needed in MariaDB.
140805 12:52:17 [Warning] 'slave-parallel-workers' is MySQL 5.6 compatible option. Not used or needed in MariaDB.
140805 12:52:17 [Warning] 'default-tmp-storage-engine' is MySQL 5.6 compatible option. To be implemented in later versions.
...

Then, just a bit later in the error log, you see the failure of gtid_mode, and MariaDB aborts:

140805 12:52:51 [ERROR] /usr/sbin/mysqld: unknown variable 'gtid_mode=OFF'
140805 12:52:51 [ERROR] Aborting