Specifications

D
evice Driver Programming
15-8
• If a system panic is repetitively occurring in a section of driver code, a
breakpoint can be set beforehand in that code in order to halt the processor
and examine the machine state before the kernel panic code is executed.
If you want to set a breakpoint during system boot, the following proce-
dure is used:
• Before booting the system (CP fb or fr /boot command), set bit 8 in pro-
cessor register boot (CP command p boot 100).
• After the boot program loads the kernel, the processor halts twice––once in
the physical memory mode before virtual memory (hereinafter referred to
as VM) is enabled and then again after VM is enabled. Breakpoints can be
set at this time using virtual addresses. The CP r command is used to
resume execution.
Although reading the entire HN6200 Console Reference Manual is highly recommended,
knowledge of the following commands facilitate most driver debugging tasks:
Table 15-1. Console Processor Commands
Command Meaning
a ASCII dump
b breakpoint manipulation
bk clear breakpoint
bt set traced breakpoints
d dump hex
di disassemble memory
e examine/change memory
g general purpose register examine/change
p processor register display/modify
qa query address
qs query stack
qv query virtual address translation
r execute run
rr run to return address
s search memory
z single step
? help