Appendix B Using the ROM Monitor
ROM Monitor Command Descriptions
Debugging Commands
Most debugging commands are functional only when Cisco IOS software has crashed or failed to initialize (boot). Debugging commands should normally be entered only under the direction of a Cisco engineer. If you enter a debugging command and Cisco IOS crash information is not available, the following error message appears:
“xxx: kernel context state is invalid, cannot proceed.”
The following ROM monitor debugging commands provide information about software failures:
•stack or
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•
•
rommon 8> sysret
System Return Info:
count: 19, reason: a SegV exception
pc:0x802b1040, error address: 0x802b1040 Stack Trace:
FP: 0x80908398, PC: 0x802b102c
FP: 0x809083b0, PC: 0x802b0b88
FP: 0x809083d8, PC: 0x8017039c
FP: 0x809083e8, PC: 0x8016f764
Configuration Register Commands
The configuration register resides in NVRAM. You can view or modify the configuration register from either the ROM monitor or the operating system software.
For procedures used to change the configuration register from the operating system, and for information about configuration register settings, see Appendix C, “Configuration Register.”
To modify the configuration register from the ROM monitor, you can:
•Enter the confreg command by itself for menu mode. See the “Modifying the Configuration Register in Menu Mode” section below.
•Enter the confreg command plus the new hexidecimal value of the configuration register. See the “Modifying the Configuration Register by Hexidecimal Entry” section on page
In either case, the new configuration register value is written into NVRAM, but is not effective until you reboot (using the ROM monitor reset command) or power cycle the router.
Cisco 3600 Series Routers Hardware Installation Guide
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