kern/48927: config(8) root on dkN doesn't work

[tnn%nygren.pp.se@localhost]

>Number:         48927
>Category:       kern
>Synopsis:       config(8) root on dkN doesn't work
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jun 19 12:50:00 +0000 2014
>Originator:     Tobias Nygren
>Release:        6.99.44
>Organization:
>Environment:
>Description:
config(8) cannot wire the rootdev configuration to dk(4) devices.

>How-To-Repeat:
Try to build kernel:

include "arch/amd64/conf/GENERIC"
no config netbsd
config netbsd root on dk7 type ffs

Notice that it fails with:

# config GENERIC.test
GENERIC.test:7: netbsd: device `dk' does not exist

Attempt to trick config(8) by adding the following to GENERIC.test:

defpseudodev dk: disk
pseudo-device dk

... does not work:

dk.o:(.data+0x80): multiple definition of `dk_cd'

(additionally it will use the wrong minor number)

>Fix:
Workaround is to manually hack the desired root device into swapnetbsd.c after 
config(8) has run.

config(8) will probably have to be specifically taught about dk(4) devices.