pg_standby and read only filesystems

Are there any known issues with pg_standby in linking mode with the WAL
source on a read only filesystem? Everything works as expected until I
touch the trigger file. When it is in copy mode everything works
perfectly.

LOG: archive recovery complete
PANIC: could not open file "pg_xlog/00000003000002E900000050" (log file
745, segment 80): Read-only file system
LOG: startup process (PID 5554) was terminated by signal 6: Aborted
LOG: aborting startup due to startup process failure

Thanks,

Paul