SMART Embedded Computing MVME2502, Installation And User Manual

Page: 123 / 150

Boot System
MVME2502 Installation and Use (6806800R96L) 123
run vxboot
6.4 Using the Persistent Memory Feature
The persistent memory means that the RAM's memory is not deleted during a reset. Power
cycling, or by temporarily removing the power and then powering up the blade again, will
delete the memory content. The persistent memory feature is enabled by default.
This feature is used in many situations, which includes:

Analyzing kernel logs after a Linux kernel panic

Defining a particular memory region for the persistent storage of application
specific data
Analyzing Kernel Log Files after a Kernel Panic
When a board that is running the Linux OS indicates a kernel panic, issue a reset (for
example, through the faceplate button) to analyze the cause, then subsequently analyze
kernel log files. The persistent memory feature keeps the log files available in the memory.
To analyze the kernel log files:
1. Issue a reset.
2. Connect to U-Boot. For more information, see
Accessing U-Boot on page 119
.
3. Enter the following command to obtain memory addresses of the kernel log
files:
.locate_kernel_log (1)
The memory addresses of any found kernel log files will be displayed.
4. Enter the following command to display the kernel logfile at any of these memory
addresses:
.printf (<memory address>)
The persistent memory is useful in application-specific data storage. The standard U-Boot
variable
pram
is used to reserve a memory region at the end of the physical memory to
prevent it from being overwritten. U-Boot reports less memory to the Linux kernel through
the
mem
parameter, indicating that the operating system should not use it either.