Well, given the excellent advice I received here (especially from Steven Schultz), I got the networking kernel to build after moving a few modules around between overlays. It was indeed the overage on DATA/BSS that was killing my build. I did a 'make install' and sync'ed, then restarted. <sigh> Now, when I respond to the boot prompt with 'ra(0,0)unix', I'm getting the following: <banner for the image, date, time, etc.> panic: iinit no fs on 5/0 I'm booting from an RD54, and checking both 'ls -l /dev/ra*' and /dev/MAKEDEV, it sure looks to me that the major device number for this drive is 5 - am I missing anything yet? That's what I called out as the ROOTDEV in my config file (in sys/conf), with '5,1' as the SWAPDEV. (I snuck a peek at the CURLY config file as well, and it shows major device 5 for ra.) Note that this is exactly the same device as I have been using all along with the GENERIC kernel, so I know there's really a filesystem there. (FWIW, I didn't define an autoboot device.) In ufs_subr.c, I see where this message is apparently generated in the getfs() function, but I can't really tell from that where it's biting me. Hey, if it wasn't a challenge, it wouldn't be fun, right? Right? TIA -- Ian PS: I'm really glad I followed the advice to copy my old (GENERIC) kernel image to 'oldunix' - so I can still boot!