[LinuxBIOS] DIMM Page Size
joe at smittys.pointclark.net
Wed Jul 11 15:41:00 CEST 2007
Quoting Segher Boessenkool <segher at kernel.crashing.org>:
>> Anyone know what the mathmatical calculation is to determine a Dimms
>> "Page Size"?? I found this but it does not seem to work:
>> Page size = (2^col)*bus_width
>> col = number of column address lines (SPD byte 4: Number of Column
>> bus_width = number of data(DQ) lines (???SPD byte 13: SDRAM Device Width???)
> "device width" is the number of data lines per DRAM chip on
> your DIMM. This isn't the same as the number of data lines
> on the DIMM itself; that is 64 usually (not counting the ECC
> bits). This info is in the SPD as well.
Ok, so that must be byte 6: Data Width of Assembly.
It still does not seem to compute though.
col = 9 /* SPD byte 4: Number of Column Addresses */
bus_width = 64 /* SPD byte 6: Data Width of Assembly */
page_size = (2^col)*bus_width
5184 = 81 * 64
Which is not correct because the DIMM has a 4k page size.
(According to it's datasheet).
Thanks - Joe
More information about the coreboot