Understanding The Rom Monitor; Understanding The Configuration Register - Cisco WS-X6066-SLB-APC - Content Switching Module Software Manual

Understanding How the Switch Boot Configuration Works
Two user-configurable parameters determine how the switch boots: the configuration register and the
BOOT environment variable. The configuration register is described in the
Configuration Register" section on page
"Understanding the BOOT Environment Variable" section on page

Understanding the ROM Monitor

The ROM-monitor code executes upon switch power up, reset, or when a fatal exception occurs. The
system enters ROM-monitor mode if the switch does not find a valid system image, if the NVRAM
configuration is corrupted, or if the configuration register is set to enter ROM-monitor mode. From
ROM-monitor mode, you can manually load a system image from Flash memory, from a network server
file, or from bootflash.
You can enter ROM-monitor mode by restarting the switch and then pressing the Break key during the
first 60 seconds of startup. If you are connected through a terminal server, you can escape to the Telnet
prompt and enter the send break command to enter ROM-monitor mode.
The Break key is always enabled for 60 seconds after rebooting the system, regardless of whether
Note
the configuration-register setting has the Break key disabled.
The following functionality is built into the ROM monitor:
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Understanding the Configuration Register

The configuration register determines whether the switch loads an operating system image and where
the system image is stored. The configuration register boot field determines if and how the ROM monitor
loads a supervisor engine system image at startup. You can modify the boot field to force the switch to
boot a particular system image at startup instead of using the default system image.
The lowest four bits (bits 3, 2, 1, and 0) of the 16-bit configuration register form the boot field. The
default boot field value is 0x10F. The possible configuration register boot field settings are as follows:
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Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
23-2
Power-on confidence test
Hardware initialization
Boot capability (allows manual boot and autoboot)
Debug utility and crash analysis
Monitor call interface (EMT calls—the ROM monitor provides information and some functionality
to the running system images via EMT calls)
File system (the ROM monitor knows the simple file system and supports the newly developed file
system through the dynamic linked file system library [MONLIB])
Exception handling
When the boot field equals 0000, the switch does not load a system image. Instead, it enters
ROM-monitor mode from which you can enter ROM-monitor commands to load a system image
manually.
When the boot field equals 0001, the switch loads the first valid system image found in onboard
Flash memory.
Chapter 23
23-2. The BOOT environment variable is described in the
Modifying the Switch Boot Configuration
"Understanding the
23-3.
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