kern/41312: panic when /dev is missing

[jeb%jeb.com.fr@localhost]

>Number:         41312
>Category:       kern
>Synopsis:       panic when /dev is missing
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 30 23:00:01 +0000 2009
>Originator:     Jean-Edouard BABIN
>Release:        NetBSD 5.0 (GENERIC) #0: Sun Apr 26 18:50:08 UTC 2009
>Organization:
>Environment:
NetBSD boumbo.jeb-intra.net 5.0 NetBSD 5.0 (GENERIC) #0: Sun Apr 26 18:50:08 
UTC 2009  
builds%b6.netbsd.org@localhost:/home/builds/ab/netbsd-5-0-RELEASE/i386/200904260229Z-obj/home/builds/ab/netbsd-5-0-RELEASE/src/sys/arch/i386/compile/GENERIC
 i386
>Description:
If you boot in read-only without /dev populated, instead of getting a mfs /dev, 
you get a panic

warning: no /dev/console
panic: init died (signal 0, exit 12)
fatal breakpoint trap in supervisor mode
trap type 1 code 0 eip c053d16c cs c6440008 eflags 246 cr2 bbbb159c ilevel 0
Stopped in pid 1.1 (init) at    netbsd:breakpoint+0x4:  popl    %ebp
db{0}> tr
breakpoint(c0a4f356,c6448c58,c0a77280,0,0,ffffffff,ffffffff,c0486497,6,ffffffff)
 at netbsd:breakpoint+0x4
panic(c0a1029c,0,c,35,c6ca3a2c,1000,c0e7fed0,0,8,0) at netbsd:panic+0x1b0
exit1(c5fd2ce0,c00,ca38dc,c5fd5ce8,c5fd2ce0,c0a7234c,c6448d3c,c05461dd,c5fd2ce0,
c6448d00) at netbsd:exit1+0x7f1
sys_exit(c5fd2ce0,c6448d00,c6448d28,c,1,bfbfeee8,804b4c1,0,0,0) at netbsd:sys_ex
it+0x4d
syscall(c6448d48,b3,ab,1f,bfbf001f,bfbfef44,bfbfef44,bfbfeee8,1,bbbb159c) at net
bsd:syscall+0xbd



>How-To-Repeat:
1. set / to mount as read-only
2. mv /dev /dev-bk
3. mkdir /dev
4. reboot

On NetBSD 5 you'll got a panic;
on netbsd 4 you got 
warning: no /dev/console
init: Creating mfs /dev
>Fix: