confreg

To change the configuration register settings while in ROM Monitor mode, use the config-register ROM Monitor command.

confreg [value]

Syntax Description

Default

Refer to your platform documentation for the default configuration register value.

Command Mode

ROM Monitor

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Not all versions in the ROM Monitor support this command. Refer to your platform documentation for more information on ROM Monitor mode.

If you use this command without specifying the configuration register value, the router prompts for each bit of the configuration register.

The lowest four bits of the configuration register (bits 3, 2, 1, and 0) form the boot field. The boot field determines if the router boots manually, from ROM, or from Flash or the network. To change the boot field value and leave all other bits set to their default values, follow these guidelines:

• If you set the configuration register boot field to 0x0, you must boot the operating system manually with the boot command.
• If you set the configuration register boot field to 0x1, the router boots using the default ROM software.
• If you set the configuration register boot field to any value from 0x2 to 0xF, the router uses the boot field value to form a default boot filename for booting from a network server.

For more information about the configuration register bit settings and default filenames, see the appropriate router hardware installation guide.

Examples

In the following example, the configuration register is set to boot the system image from Flash memory:

rommon 2 > confreg 0x210F

In the following example, no configuration value is entered, so the system prompt for each bit in the register:

rommon 7 > confreg
   
   Configuration Summary
   enabled are:
   console baud: 9600
   boot: the ROM Monitor
   
   do you wish to change the configuration? y/n [n]: y
   enable "diagnostic mode"? y/n [n]: y
   enable "use net in IP bcast address"? y/n [n]: 
   enable "load rom after netboot fails"? y/n [n]: 
   enable "use all zero broadcast"? y/n [n]: 
   enable "break/abort has effect"? y/n [n]: 
   enable "ignore system config info"? y/n [n]: 
   change console baud rate? y/n [n]: y
   enter rate: 0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400 [0]: 0
   change the boot characteristics? y/n [n]: y
   enter to boot:
   0 = ROM Monitor
   1 = the boot helper image
   2-15 = boot system
   [0]: 0
   
   Configuration Summary
   enabled are:
   diagnostic mode
   console baud: 9600
   boot: the ROM Monitor
   
   do you wish to change the configuration? y/n [n]: 
   You must reset or power cycle for new config to take effect.
   rommon 8>