"ffs_mountroot: can't find rootvp

[markjose]

Greetings,

I have just built a kernel (after a fresh install of 5.3 CD release),
and have encountered this message:

Mounting root from ufs:/dev/ad2s1a
Setroutbyname failed
ffs_mountroot: can't find rootvp
Root mount failed: 6

The reason it failed is because now the kernel detects the ata disk
(master on the secondary) as ad0 rather than previously ad2 (eg using
/stand/sysinstall). Why?

Cheers