Cisco Systems CSR 1000V manual Accessing Grub Mode, Boot Field, Enable Config-register, 11-2

Chapter 11 Accessing and Using GRUB Mode

Accessing GRUB Mode

Table 11-2describes the boot field, which is the lowest four bits of the configuration register (bits 3, 2, 1, and 0). The boot field setting determines whether the router loads an operating system.

Table 11-2 Boot Field Configuration Register Bit Descriptions

Boot Field
(Bits 3, 2, 1, and 0)	Meaning
0000	At the next power cycle or reload, the router boots to the GRUB (bootstrap
(0x0)	program).
	In GRUB mode, you must manually boot the system image or any other image by
	using the boot command.
0001 - 1111	At the next power cycle or reload, the router sequentially processes each boot
(0x01 - 0x0F)	system command in global configuration mode that is stored in the configuration
	file until the system boots successfully.
	If no boot system commands are stored in the configuration file, or if executing
	those commands is unsuccessful, then the router attempts to boot the first image
	file in flash memory.

Note Use the 0x000 setting to configure the Cisco CSR 1000V to automatically enter GRUB mode when the router boots.

Accessing GRUB Mode

Perform the following step to access GRUB mode:

SUMMARY STEPS

1.enable

2.config-register 0x0000

DETAILED STEPS

	Command or Action	Purpose
Step 1
	enable	Enables privileged EXEC mode.
		• Enter your password if prompted.
	Example:
	Router> enable
Step 2
	config-register 0x0000	Enters the GRUB mode by entering the “0000” value
		(0x0).
	Example:
	Router# config-register 0x0000

	Cisco CSR 1000V Series Cloud Services Router Software Configuration Guide
11-2	OL-27477-07