Motorola MCP750 Specifications download pdf (Page 263)

Driver Testing and Debugging

15-1

The system automatically saves the dump image when it detects an improper shutdown.

By default, when entering multi-user mode, the memory image and the kernel image are

saved to /var/crashfiles.

NOTE

To reduce the amount of memory to be copied to disk at a system

crash, you can reduce the amount of RAM used by the system by

using the MAXPMEM tunable parameter. This parameter is set in

the /etc/conf/mtune.d/kernel ﬁle.

Initializing crash on the Memory Dump 15

To run crash on the core image of memory at the time the system panicked, you must

have saved the core image before rebooting and the file containing the kernel bootable

image (/stand/unix ﬁle by default) that was running at the time of the crash.

If the bootable kernel image is named something other than /stand/unix (either

because it was named something else at the time of the panic or because you copied it to

another name after the panic), use the -n option or the second positional parameter to

specify that file name. If you want the output of crash to be written to a file rather than

your terminal (standard output), use the -w option with the name of the ﬁle. Note that the

output of a speciﬁc crash command can be redirected to a ﬁle even if you do not use the

-w in the crash command line.

Using crash Functions 15

The crash session begins by reporting the dumpfile, namelist, and outfile being used, fol-

lowed by the crash prompt (>). Requests in the crash session have the following stan-

dard format

command [argument...]

where command is one of the supported commands of crash and argument includes any

qualifying data relevant to the requested command. Use the q command to end the crash

session.

See the crash(1M) manual page for a list of supported commands. Note that, while

most crash commands are common to all computers, each system also has unique

commands that relate to speciﬁc devices supported on that machine.

Following is a list of crash commands often useful when debugging a driver.

dis Disassemble from a starting address. Use this information to trace

code flow. However, you have to mentally convert the resulting

assembler code to C programming language statements.

od List memory. Use this command when you suspect that the stack

is corrupted, or to list the contents of memory at a certain address.

If you are listing the contents of the stack, you have to manually

ﬁnd the boundaries of each stack entry, called stack frames. To get

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Motorola MCP750 Specifications Page 263