Starting kadb

In order to start up kadb, the system must be booted with kadb(1M) enabled:

ok boot kadb
...
Rebooting with command: boot kadb
Boot device: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@0,0:a
File and args: kadb
kadb: kernel/sparcv9/unix
Size: 499808+109993+132503 Bytes
/platform/sun4u/kernel/sparcv9/unix loaded - 0x11e000 bytes used
SunOS Release 5.9 Version Generic 64-bit
Copyright 1983-2002 Sun Microsystems, Inc.  All rights reserved
....

By default, kadb(1M) boots (and debugs) kernel/unix, or kernel/sparcv9/unix on a system capable of running a 64-bit kernel. To boot kadb with an alternate kernel, pass the -D flag to boot, as follows:

ok boot kadb -D kernel.test/unix
...
Rebooting with command: boot kadb -D kernel.test/unix
Boot device: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@0,0:a  File
and args: kadb -D kernel.test/unix
kadb: kernel.test/unix
Size: 482384+67201+88883 Bytes
/platform/sun4u/kernel.test/unix loaded - 0xfe000 bytes used
SunOS Release 5.9 Version dacf-fixes:11/13/99 32-bit
Copyright 1983-2002 Sun Microsystems, Inc.  All rights reserved.
...

In this example, the 32-bit version of the alternate kernel kernel.test was booted. Another option is to pass kadb the -d flag, which causes kadb to prompt for the kernel name. The -d flag also causes kadb(1M) to provide a prompt after it has loaded the kernel, so breakpoints can be set.

ok boot kadb -d
...
Rebooting with command: boot kadb -d
Boot device: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@0,0:a  File
and args: kadb -d
kadb: kernel.test/unix
Size: 482384+67201+88883 Bytes
/platform/sun4u/kernel.test/unix loaded - 0xfc000 bytes used
stopped at      _start:         sethi   %hi(0x10006c00), %g1
kadb[0]: 

At this point you can set breakpoints or continue execution with the :c command.

Kernel modules are dynamically loaded. Consequently, driver symbols are not available until the driver is loaded. To set breakpoints in modules that have not been loaded, use deferred breakpoints. For information on deferred breakpoints, refer to Breakpoints.

kadb(1M) passes any kernel flags to the booted kernel. For example, to boot an alternate kernel and pass the -r flag:

ok boot kadb -r -D kernel.test/unix
...
Rebooting with command: boot kadb -r -D kernel.test/unix
Boot device: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@0,0:a
File and args: kadb -r -D kernel.test/unix
kadb: kernel.test/unix
Size: 482384+67201+88883 Bytes
/platform/sun4u/kernel.test/unix loaded - 0xfe000 bytes used
SunOS Release 5.9 Version Generic 32-bit
Copyright 1983-2002 Sun Microsystems, Inc.  All rights reserved.
obpsym: symbolic debugging is available.
Read 208377 bytes from misc/forthdebug
configuring IPv4 interfaces: le0.
Hostname: test
Configuring /dev and /devices

After the system is booted, sending a break passes control to kadb(1M). A break is generated with STOP-A (on the console of SPARC machines), or with F1-A (on the console of IA machines), or by using ~# (if the console is connected through a tip window).

...

The system is ready.

test console login: ~#
stopped at      edd000d8:       ta      %icc,%g0 + 125
kadb[0]: 

The number in brackets is the CPU that kadb(1M) is currently executing on; the remaining CPUs are halted. The CPU number is zero on a uniprocessor system.

Before rebooting or turning off the power, always halt the system cleanly (with init 0 or shutdown). Buffers might not be flushed otherwise. If the shutdown must occur from the boot PROM prompt, make sure to flush buffers using the sync command at the ok prompt.

To return control to the operating system, use :c.

kadb[0]: :c
test console login: