panic on devd disable

[Ken Menzel]

On my older Dell 2400 and 2500 systems I have been setting 
devd_enable="NO" to avoid panicing the systems.  Now I when I updated to 
7.2p5 the following sysctl seems to panic the system at will.

sysctl hw.bus.devctl_disable=1

I have removed /etc/rc.d/devd completely to get the system to boot into 
multiuser.  I have a GENERIC Kernel and nothing in make.conf.

I enabled set -x in rc.conf and rebooted to get this back trace

Does anyone have any ideas why this happens or what patch I might try to 
fix it?
 Thanks,
Ken

Here is backtrace

<118>eval
<118> _value=$devd_enable
<118>
<118>+
<118>_value=NO
<118>
<118>+
<118>debug
<118> checkyesno: devd_enable is set to NO.
<118>
<118>+
<118>return
<118> 1
<118>
<118>+
<118>sysctl
<118> hw.bus.devctl_disable=1
<118>
<118>hw.bus.devctl_disable:
<118>0


Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 00
fault virtual address   = 0xff000008
fault code              = supervisor write, page not present
instruction pointer     = 0x20:0xc080a1fa
stack pointer           = 0x28:0xefc07b34
frame pointer           = 0x28:0xefc07b54
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 406 (sysctl)
trap number             = 12
panic: page fault
cpuid = 1
Uptime: 6m45s
Physical memory: 2035 MB
Dumping 69 MB: 54 38 22 6

Reading symbols from /boot/kernel/acpi.ko...Reading symbols from /boot/kernel/acpi.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/acpi.ko
#0  doadump () at pcpu.h:196
196             __asm __volatile("movl %%fs:0,%0" : "=r" (td));
(kgdb) bt
#0  doadump () at pcpu.h:196
#1  0xc07e25f7 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:418
#2  0xc07e28c9 in panic (fmt=Variable "fmt" is not available.
) at /usr/src/sys/kern/kern_shutdown.c:574
#3  0xc0ae3f2c in trap_fatal (frame=0xefc07af4, eva=4278190088)
    at /usr/src/sys/i386/i386/trap.c:939
#4  0xc0ae41b0 in trap_pfault (frame=0xefc07af4, usermode=0, eva=4278190088)
    at /usr/src/sys/i386/i386/trap.c:852
#5  0xc0ae4b5c in trap (frame=0xefc07af4) at /usr/src/sys/i386/i386/trap.c:530
#6  0xc0ac926b in calltrap () at /usr/src/sys/i386/i386/exception.s:159
#7  0xc080a1fa in sysctl_devctl_disable (oidp=0xc0c546e0, arg1=0x0, arg2=0,
    req=0xefc07ba4) at /usr/src/sys/kern/subr_bus.c:733
#8  0xc07ebe97 in sysctl_root (oidp=Variable "oidp" is not available.
) at /usr/src/sys/kern/kern_sysctl.c:1413
#9  0xc07ec034 in userland_sysctl (td=0xc5949d20, name=0xefc07c14, namelen=3,
    old=0x0, oldlenp=0x0, inkernel=0, new=0xbfbfee64, newlen=4,
    retval=0xefc07c10, flags=0) at /usr/src/sys/kern/kern_sysctl.c:1506
#10 0xc07ec184 in __sysctl (td=0xc5949d20, uap=0xefc07cfc)
    at /usr/src/sys/kern/kern_sysctl.c:1443
#11 0xc0ae4505 in syscall (frame=0xefc07d38)
    at /usr/src/sys/i386/i386/trap.c:1090
#12 0xc0ac92d0 in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:255
#13 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)
(kgdb)