Functional Description
5.23.2
Flash Descriptor
The maximum size of the Flash Descriptor is 4 KB. If the block/sector size of the SPI
flash device is greater than 4 KB, the flash descriptor will only use the first 4 KB of the
first block. The flash descriptor requires its own block at the bottom of memory
(0x00h). The information stored in the Flash Descriptor can only be written during the
manufacturing process as its read/write permissions must be set to Read only when the
computer leaves the manufacturing floor.
The Flash Descriptor is made up of eleven sections:
Figure 5-17. Flash Descriptor Sections
4KB
OEM Section
Descriptor
Upper MAP
Management
Engine VSCC
Table
Reserved
MCH Soft
Straps
ICH Soft
Straps
Master
Region
Component
Descriptor
MAP
Signature
0
1. The Flash signature selects Descriptor Mode as well as verifies if the flash is
programmed and functioning. The data at the bottom of the flash (offset 0) must be
0FF0A55Ah in order to be in Descriptor mode.
2. The Descriptor map has pointers to the other five descriptor sections as well as the
size of each.
232
Datasheet
INTEL [ INTEL ]
