gmirror does not initialize properally

[Aryeh M. Friedman]

I have started the procedure for mirroring drives and everything works 
fine upto its first mount attempt (read only root... premounted before 
/etc/rc runs) and then sees no slices... what I mean is 
/dev/mirror/gm0Sxy never appears in the ls of /dev/mirror [bur 
/dev/mirror/gm0 does _exist_).... here is the output from kldstat:

Id Refs Address    Size     Name
 1   19 0xc0400000 94f054   kernel
 2    1 0xc0d50000 84c4     linprocfs.ko
 3    3 0xc0d59000 27744    linux.ko
 4    1 0xc0d81000 161c8    geom_mirror.ko
 5    1 0xc0d98000 15484    snd_hda.ko
 6    2 0xc0dae000 4938c    sound.ko
 7    1 0xc0df8000 23e4     accf_http.ko
 8    1 0xc0dfb000 75aa64   nvidia.ko
 9    1 0xc1556000 68304    acpi.ko