Artesyn ATCA-8310 Installation and Use (May 2014) - Manual (Page 199)

U-Boot
ATCA-8310 Installation and Use (6806800M72E) 199
6.2.1.15 Troubleshooting
6.2.1.15.1 Recovering from Corrupted Environment Variables
It is theoretically possible to configure the NVRAM variables so that u-boot does not start any
more. This would also make it impossible to repair the bad environment data.
There are two methods to recover from such a scenario:
1. Removing/changing the offending parameter setting by accessing the IPMI boot
parameter storage from extern (e.g. via the shelf manager using the hpibootparameter
command).
2. Certain variables read very early during the boot process (e.g. the "hwconfig" or "baudrate"
variables) can not be altered via the IPMI boot parameter storage.
For that case it is possible to enable a "failsafe" mode by writing to a specific register in the
glue logic FPGA via the IPMI controller (scratch register at offset 0x7c). This register is
evaluated before the first access to the EEPROM, and if u-boot finds the magic value 0xdc
it will ignore the EEPROM contents and boot with the default parameter set.
The IPMI command to enable the recover mode (using the ipmicmd tool from the shelf
manager) is:
ipmicmd -k "0 0 2e 30 cd 65 00 7c 0xdc
where is the ipmb address of the blade to be accessed.
Other supported values for the scratch register are:
 0x09 to perform a memory voltage margin test on DDR3 interface 0 / DIMM0
 0x0a to perform a memory voltage margin test on DDR3 interface 1 / DIMM1
 0x0b to perform a memory voltage margin test on DDR3 interface 1 / DIMM1 and the CPU
interface
 0xcc to perform the DRAM configuration as if it is a power-up