"Fatal trap 12" while debugging a 4.11 kernel with remote gdb

[Björn König]

Hello,

I'm trying to debug a FreeBSD 4.11 kernel that has been compiled with

     makeoptions DEBUG=-g
     options     DDB

The remote machine is running FreeBSD 5.4 and I'm using devel/gdb6. I 
have no problems as long as I escape to the debugger after the kernel 
was loaded, but I like to trace something during the initialisation. I 
type 'boot -d', 'gdb' and 's' on the 4.11 machine and the following 
commands on the 5.4 machine:

(kgdb) s
Reply contains invalid hex digit 84
(kgdb) s
Warning:
Cannot insert breakpoint -1.
Error accessing memory address 0xc02f09a8: Input/output error.

At the same time of the second 'step' this happens with the 4.11 kernel:

Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0xf0010502
fault code              = supervisor read, page not present
intruction pointer      = 0x8:0xc02ed6b6
stack pointer           = 0x10:0xc045de3c
frame pointer           = 0x10:0xc045de48
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         = Idle
interrupt mask          = net tty bio cam

Does anyone has a hint for me to prevent this?

Thanks in advance
Björn