The various Rockchip SoCs seem to favour 1500000 for the serial console speed. And since for some of those we still have to rely on closed source firmware components, I think I'll have to bite the bullit and properly support this. Here is a first diff that adds an appropriate entry to gettytab(5). Not entirely sure whether the 1500000-baud alias is necessary. But I don't think it'll hurt us.
ok? Index: etc/gettytab =================================================================== RCS file: /cvs/src/etc/gettytab,v retrieving revision 1.5 diff -u -p -r1.5 gettytab --- etc/gettytab 10 Dec 2013 20:56:59 -0000 1.5 +++ etc/gettytab 1 May 2018 18:51:45 -0000 @@ -47,6 +47,8 @@ std.57600|57600-baud:\ :sp#57600: std.115200|115200-baud:\ :sp#115200: +std.1500000|1500000-baud:\ + :sp#1500000: # # Dial in rotary tables, speed selection via 'break'