[LinuxBIOS] DIMM Page Size
segher at kernel.crashing.org
Wed Jul 11 18:42:35 CEST 2007
>>> 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 Addresses)
>>> 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.
2**9 * 64 = 512 * 64 = 32k bits = 4kB.
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