Prepare and Boot an Alternate Kernel

A good strategy to avoid rendering a system inoperable is to make a copy of the kernel and associated binaries, and to boot that instead of the default kernel. To do so, make a copy of the drivers in /platform/* as follows:

# cp -r /platform/'uname -i'/kernel /platform/'uname -i'/kernel.test

When developing your driver, place it in /platform/`uname -i`/kernel.test/drv and boot that kernel instead of the default kernel:

# reboot -- kernel.test/unix

or from the PROM:

ok boot kernel.test/unix

This results in the test kernel and drivers being booted:

Rebooting with command: boot kernel.test/unix
Boot device: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@0,0:a  File and args:
kernel.test/unix
SunOS Release 5.8 Version Generic 32-bit
Copyright 1983-2000 Sun Microsystems, Inc.  All rights reserved.
...

Alternately, the module path can be changed by booting with the ask (-a) option:

ok boot -a

This results in a series of prompts which you can use to configure the way the kernel boots:

Rebooting with command: boot -a
Boot device: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@0,0:a  File and args: -a
Enter filename [kernel/sparcv9/unix]: kernel.test/sparcv9/unix
Enter default directory for modules
[/platform/sun4u/kernel.test /kernel /usr/kernel]: <CR>
Name of system file [etc/system]: <CR>
SunOS Release 5.8 Version Generic 64-bit
Copyright 1983-2000 Sun Microsystems, Inc.  All rights reserved.
root filesystem type [ufs]: <CR>
Enter physical name of root device
[/sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@0,0:a]: <CR>