Hello,

after entering ddb several times, setting and removing breakpoints, I
pressed ctrl+alt+esc to enter ddb and the kernel immediately crashed
(exited to SRM console). When I rebooted, following messages were found
in dmesg:

---cut here
CPU 0    a1         = 0x1
CPU 0    a2         = 0x1
CPU 0    pc         = 0xfffffc00009ec71c
CPU 0    ra         = 0xfffffc0000619988
CPU 0    pv         = 0xfffffc00009ec6e0
CPU 0    curproc    = 0x0

panic: trap

CPU 0: fatal kernel trap:

CPU 0    trap entry = 0x2 (memory management fault)
CPU 0    a0         = 0x6469726220657465
CPU 0    a1         = 0x1
CPU 0    a2         = 0x1
CPU 0    pc         = 0xfffffc00009ec71c
CPU 0    ra         = 0xfffffc0000619988
CPU 0    pv         = 0xfffffc00009ec6e0
CPU 0    curproc    = 0x0
---cut here
... repeated many times.

I guess pc is a program counter, so I ran gdb on the kernel:

---cut here
Script started on Thu Jan 16 08:55:06 2003
bash-2.05$ gdb netbsd.gdb
GNU gdb 5.0nb1
Copyright 2000 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "alpha-unknown-netbsd"...
(gdb) info line *0xfffffc00009ec71c
Line 255 of "/usr/src/sys/arch/alpha/alpha/db_interface.c"
   starts at address 0xfffffc00009ec710 <db_write_bytes+48>
   and ends at 0xfffffc00009ec72c <db_write_bytes+76>.
(gdb) disas db_write_bytes+48 db_write_bytes+76
Dump of assembler code from 0xfffffc00009ec710 to 0xfffffc00009ec72c:
0xfffffc00009ec710 <db_write_bytes+48>: mov     t2,t3
0xfffffc00009ec714 <db_write_bytes+52>: mov     t1,t4
0xfffffc00009ec718 <db_write_bytes+56>: ldbu    t5,0(t4)
0xfffffc00009ec71c <db_write_bytes+60>: stb     t5,0(t3)
0xfffffc00009ec720 <db_write_bytes+64>: addq    t1,0x1,t1
0xfffffc00009ec724 <db_write_bytes+68>: addq    t2,0x1,t2
0xfffffc00009ec728 <db_write_bytes+72>: 
    br  0xfffffc00009ec700 <db_write_bytes+32>
End of assembler dump.
(gdb) quit
---cut here

Line 255 of db_interface.c is:

		*dst++ = *data++;

Is this related to PR kern/10016 or is it a separate issue?

Pavel