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3.5.2 User Flash
The 8 MBytes of Boot Flash appears at the top of the User Flash area, with the four
boot images appearing in their physical locations unaffected by the state of links P2
1-2 and 3-4 (see above). The remainder of the Flash array is available as User Flash
and appears as a contiguous block below this. This Flash area is intended to hold
user application code or data.
3.5.3 Flash Sector Protection
The Spansion S29GL512P Flash devices provide advanced methods of sector
protection to ensure the integrity of code data contained in the Flash array.
Protection is available for each 128 KByte sector. Locked sectors cannot be erased or
programmed; they may only be read.
Hardware provides no Flash write protection; software must be used to configure
the Flash devices to protect against corruption of Flash data. The following types of
protection are provided:
1. Persistent sector protection provides non-volatile protection that remains in place
2. Non-persistent protection may also be used. This protection is only present until
The IMP2B boot software uses the non-persistent protection method to lock the
sectors in the Boot or User Flash areas depending on the state of the
Flash Write Enable Links (P3 3-4 and
compatible with existing hardware (where Flash write protection was provided by
hardware mechanisms).
For further details of these protection mechanisms, refer to the Spansion data sheet.
20 IMP2B 3U cPCI Single Board Computer
when a board is power-cycled or reset. Each Flash sector may be set as locked
(write-protected) or unlocked (write-enabled) by writing to configuration
registers within the Flash. The configuration of this protection is only possible
when the
Flash Protection Password Unlock Link (P3 1-2)
fitted on this link, the software is unable to change the sector protection and
those sectors that are locked may not be erased or reprogrammed under any
circumstances.
a power cycle or hardware reset occurs and may be modified by user software.
NOTE
Sectors that are locked using the Persistent mode may not be unlocked using this mechanism.
NOTE
Do not rely on non-persistent protection, as it may be subsequently altered by software. If further
protection is required, use the Persistent protection method.
LINK
http://www.spansion.com/support/technical_documents/flash_datasheets.html
5-6). This provides a protection mode
is fitted. If no jumper is
Boot and User
Publication No. IMP2B-0HH/5
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