Why am I getting Kernel Panic VFS cannot mount root fs on 301?

[Joe Burks]

Unfortunately I cannot copy the exact text I'm getting, but it is something 
similar to that.  Now that I have time again, I desperately need to maintain 
drivers/usb/media/vicam.c again and am trying to boot 2.5.70 to do so.  
Here's what I've tried:

Freshly installed debian woody
Freshly downloaded 2.5.70
Downloaded, compiled and installed init-module-utils 0.9.12 from Rusty's site.
Downloaded, compiled and installed latest devfsd (although it currently does 
not seem to get to a point where this would matter, it never mounts the root 
fs in order to start devfsd)
Carefully followed instructions in Documentation/filesystems/devfs/README on 
setting up devfs for the impatient.
Configured kernel, including enabling devfs and devfs_mount.
make bzImage modules modules_install install (not in one line, one at  a time)
went into lilo.conf and added an append="root=<device>" line, then re-ran 
lilo.  (where I say <device> I have tried about 100 different possibilities 
ranging from easy ones like /dev/hda1 or /dev/discs/disc0/part1 to 
/dev/ide/...)  Obviously I only get the "301" error when the root= line is 
missing and I let lilo write that magic value.

No matter what root= line I supplied it just wouldn't boot.  I've also tried 
devfs=mount, devfs=nomount all to no solution.  So in frustration I rebuilt 
the kernel without devfs, since I figured that is where my problem was, but 
the exact error is still occurring.  I tried both leaving in a root= and 
removing the root= append line with devfs not installed.

I can still boot fine with whichever kernel woody installed (2.4.16 I think).

I don't think this is a devfs problem.  I think there is some subtle (or maybe 
blatantly obvious) kernel option I have not checked which would cause the 
whole situation to go away.

Does anybody know what this option is?

Thanks
-Joe