Cisco 3725 Software Configuration Guide - Page 185

Appendix C Using the ROM Monitor Entering the ROM Monitor Mode - upgrade rom-monitor preference-Selects the version of ROMMON to be loaded the next time the router is reloaded. This command is used in the Cisco IOS exec mode. - rommon-pref-Used in ROMMON command mode. Provides the same information as upgrade rom-monitor preference command in the Cisco IOS exec mode. Debugging Commands Most debugging commands are functional only when Cisco IOS software has crashed or is aborted. 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, can not proceed." • stack or k-Produces a stack trace. • context-Displasy processor context. • frame-Displays an individual stack frame. • sysret-Displays return information from the last booted system image. This information includes the reason for terminating the image, a stack dump of up to eight frames, and, if an exception is involved, the address where the exception occurred. For example: 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 virtual configuration register resides in NVRAM. You can display or modify the virtual configuration register from either the ROM monitor or the operating system software. To change the virtual configuration register from the ROM monitor, enter the confreg command by itself for menu mode, or enter the new value of the register in hexadecimal. • confreg [hexnum]-Changes the virtual configuration register to the value specified. The value is always interpreted as hexadecimal. Note Entering confreg without an argument displays the contents of the virtual configuration register and prompts you to alter the contents by describing the meaning of each bit. In either case, the new virtual configuration register value is written into NVRAM, but is not effective until you reset or power-cycle the router. The following display shows an example of the confreg command: rommon 7 > confreg Configuration Summary enabled are: OL-1957-04 Software Configuration Guide for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers C-5