[LinuxBIOS] DIMM Page Size
myles at pel.cs.byu.edu
Wed Jul 11 16:50:22 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
> >> where,
> >> 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
> > "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.
> > Segher
> 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
2^9 = 512
> 5184 = 81 * 64
512 * 64 = 32K
> Which is not correct because the DIMM has a 4k page size.
> (According to it's datasheet).
> Please Help.
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