Merge pull request 'Add info about E6400 flash size + PCB numbers' (#23) from nic3-14159/lbwww:e6400-spi-sizes into master

Reviewed-on: https://codeberg.org/libreboot/lbwww/pulls/23

site/docs/hardware/e6400.md

@@ -65,9 +65,27 @@ We believe all models with iGPU are GM45 and will work perfectly. We suspect
 that the dGPU models are PM45 and won't work yet, because Libreboot currently
 supports just the iGPU (Intel graphics) on these machines.
 
-There are two possible flash chip sizes for the E6400: 4MiB (32Mbit) or
+There are two possible flash chip sizes for the E6400: 4MiB (32Mbit) or 2+4MiB
-2+4MiB (64Mbit). Libreboot presently supports the 4MiB version, and provides
+(16Mbit+32MBit). Libreboot presently supports the 4MiB version, and provides
-8MiB images for those who upgrade their flash to 8MiB or 16MiB.
+8MiB images for those who upgrade their flash to 8MiB or 16MiB. There appears
+to be several possible mainboard PCBs for the E6400, which we believe mostly
+affects the GPU configuration and the number of available SPI flash footprints:
+
+- LA-3801P: iGPU, possibly dual SPI (however only one may be populated)
+- LA-3803P: dGPU, dual SPI (however only one may be populated)
+- LA-3805P: iGPU, single SPI flash (4MiB)
+- LA-3806P: dGPU, unknown SPI configuration (likely at least 4MiB)
+
+These PCB numbers can be found either under the black plastic in the RAM slots
+on the bottom (CPU side) of the board, the top left corner near the VGA port
+(top side, under the keyboard and palmrest), or near the CPU backplate (only
+requires removal of the keyboard).
+
+We believe that all boards will have at least a single 4MiB flash chip,
+regardless of the number of SPI footprints. This is likely the most common
+configuration on most available systems. The 2+4MiB configuration likely
+would have only been used on systems with full Intel ME firmware with AMT
+functionality, though this configuration has not yet been encountered.
 
 Most people will want to use the 4MiB images.