The watchpoint length specifier syntax recognized by MDB is different from the syntax described in adb. In particular, the adb watchpoint commands :w, :a, and :p allow an integer length in bytes to be inserted between the colon and the command character. In MDB, the count should be specified following the initial address as a repeat count. Stated simply, these adb commands:
123:456w 123:456a 123:456p
are specified in MDB as:
123,456:w 123,456:a 123,456:p
The MDB ::wp dcmd provides more complete facilities for creating user process watchpoints. Similarly, the legacy kadb length modifier command $l is not supported. Therefore, the watchpoint size should be specified to each ::wp command used in kmdb.