Core Issue
When the image decompresses into memory and hits a bad spot in the memory, the checksum is thrown off and the error is produced. This may occur after a Cisco IOS upgrade to a larger Cisco IOS image than was previously running on the router. Other error messages, such as *** System received a Software forced crash *** and *** System received a Bus Error exception *** often accompany the checksum error.
This is a sample output of the error message:
Self decompressing the image :
####################################################################################################
################[OK]
Error : pre and post compression image sizes disagree
*** System received a Software forced crash ***
signal= 0x17, code= 0x8, context= 0x0
PC = 0x800080d4, Cause = 0x20, Status Reg = 0x3040d003
System Bootstrap, Version 12.0(20000211:194150) [dperez-cosmos_e_ecc
106], DEVELOPMENT SOFTWARE
Copyright (c) 1994-2000 by cisco Systems, Inc.
C7200 platform with 131072 Kbytes of main memory
Self decompressing the image :
####################################################################################################
#################[OK]
Restricted Rights Legend
Use, duplication, or disclosure by the Government is
subject to restrictions as set forth in subparagraph
(c) of the Commercial Computer Software - Restricted
Rights clause at FAR sec. 52.227-19 and subparagraph
(c) (1) (ii) of the Rights in Technical Data and Computer
Software clause at DFARS sec. 252.227-7013.
cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134-1706
Cisco Internetwork Operating System Software
IOS (tm) 7200 Software (C7200-JS-M), Version 12.2(3), RELEASE SOFTWARE
(fc1)
Copyright (c) 1986-2001 by cisco Systems, Inc.
Compiled Wed 18-Jul-01 10:50 by pwade
Image text-base: 0x600089C0, data-base: 0x61704000
signal= 0xA, code= 0x8, context= 0x62554F60
=== Flushing messages () ===
-Traceback= 616FF3A0 605F549C 605344F0 60534930 605D3CCC 605D3CB8
*** System received a Bus Error exception ***
signal= 0xa, code= 0x8, context= 0x62554f60
PC = 0x6060132c, Cause = 0x20, Status Reg = 0x34008002
Resolution
If the checksum error is displayed, perform these steps:
- If the router is in a boot loop, enter a break sequence (ctrl-break with Hyperterminal) to get the router to the rommon> prompt.
- At the rommon> prompt, issue the dir device: command to see the image on Flash and to verify the image size, as shown in this example:
rommon 1 > dir flash:
program load complete, entry point: 0x80008000, size: 0xb2a0
Directory of flash:
2 6821196 -rw- c3725-i-mz.122-8.T5.bin
- Verify that the image is the correct size.
In this example, the size of the file is 6,821,196 bytes. The size should agree exactly with the size shown when downloading the image at Cisco Downloads.
- Verify that the router has sufficient DRAM to support the image. Issue the meminfo command at the rommon> prompt, as shown in this example:
rommon 1 > meminfo
-------------------------------------------------
Current Memory configuration is:
Dimm0: Size = 128 MB : Start Addr = 0x00000000
-----Bank 0 128 MB
-----Bank 1 0 MB
Dimm1: Size = 128 MB : Start Addr = 0x08000000
-----Bank 0 128 MB
-----Bank 1 0 MB
-------------------------------------------------
Main memory size: 256 MB in 64 bit mode.
Available main memory starts at 0xa000e000, size 262088KB
IO (packet) memory size: 25 percent of main memory.
IO memory is configured by user
NVRAM size: 32KB
rommon 2 >
This example shows that the router has 256 MB of DRAM.
- If the Cisco IOS image is valid and the router has enough memory to support the image, yet the Error : pre and post compression image sizes disagree error message still occurs, replace the DRAM.
- If the issue only arose after a Cisco IOS upgrade, use a temporary workaround to get the router running again. This workaround is to load the previous image back on to the Flash until the replacement memory is installed. The reason the previous image may load is that if it is smaller (and therefore does not get to the defective part of DRAM when the image is decompressed), it loads the image correctly.
- Another way to determine whether the DRAM is defective is to issue the show region command. This determines whether the address in the bus error message is pointing to memory.
For more information, refer to Troubleshooting Bus Error Crashes.
Crash Types
Software forced crash
When Problem Occurs
Continuously
After software upgrade
Error Messages and Warnings
*** System received a Bus Error exception ***
*** System received a Software forced crash ***
Error : compressed image checksum is incorrect
Error : pre and post compression image sizes disagree
