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Appendix A - Statement of Volatility
Types of Memory
The Raptor contains the following volatile and non-volatile memory:
|MicroSD Flash Card||Non-volatile||Varies, typically 8 GBytes\(1 device)||File system for embedded microprocessor||Yes|
|QSPI Flash||Non-volatile||125 MBytes|
|MPSoC Memory||Volatile||4 GBytes DDR4 attached to processing system|
|MPSoC OCM RAM||Volatile||256 KBytes|
|EEPROM||Non-volatile||32 Kbytes||Static system configuration storage||No|
Volatile memories do not retain their data after the system power has been removed. Non-volatile memories do retain their data after the system power has been removed.
The non-volatile memories on the Raptor board can be write-protected, rendering them read-only memories. When the memories are write-protected, no data can be stored to them. The write protect controls are configured with the SW1 DIP switch (see Figure A.2).
The EEPROM is write-protected when position 3 of the DIP switch is ON. The EEPROM is write- enabled when postion 3 of the DIP switch is OFF. This switch should only be toggled when the unit is powered off.
The microSD flash card is write-protected when position 4 of the DIP switch is ON. When position 4 of the DIP switch is OFF, the microSD FLASH card is write- enabled.
Because the microSD flash card contains the file-system for the embedded microprocessor, care must be taken to mount the file system as read-only before write-protecting the flash card.
To write-protect the file-system:
- Log-in to the system as root.
- Issue the command: mount –o remount,ro /
- Issue the command: shutdown
- Power-off the system once shutdown has completed.
- Change the DIP switch to the write-protected position.
- Power-on the system.
To write-enable the system:
- Power down the system.
- Change the DIP switch to the write-enabled position.
- Power-on the system.
A signal can also be applied to the write-protect header to control the write- protect state of the microSD flash card remotely. Consult the factory for details on using this signal.
To verify the microSD flash card is write-protected, issue the following mount command to attempt to mount the microSD flash card as read-write.
mount -o remount,rw /
The following error message will be returned:
mount: cannot remount /dev/root read-write, is write-protected