[LinuxBIOS] SPD Logical and Physical Banks

joe at smittys.pointclark.net joe at smittys.pointclark.net
Tue May 15 19:48:13 CEST 2007


Quoting Uwe Hermann <uwe at hermann-uwe.de>:

> On Tue, May 15, 2007 at 04:45:53AM -0400, Corey Osgood wrote:
>> joe at smittys.pointclark.net wrote:
>> > Hello,
>> > Can someone please explain to me the difference between Logical and
>> > Physical Banks on SDRAM? I am looking for a quick and dirty way to
>> > determine if the SDRAM module is single sided or double sided through
>> > SPD. Would I use the Logical (SPD Byte 17) or Physical (SPD Byte 5)
>> > Bank for that?
>> >
>> > Thanks - Joe
>> >
>>
>> Well, in the best case, neither. Read the Intel SPD standard
>> (http://www.intel.com/design/chipsets/memory/spdsd12a.pdf), I've checked
>> several PC66, 100, and 133 dimms, and all of them so far support it.
>> Check out bytes 126 and 127. If that doesn't work out though, you're
>> looking for byte 5.
>
> Just to prevent unnecessary duplicated work: please don't write
> SPD-related functions for 440BX. I'm about to finish a patch which moves
> all generic SPD-related functions into src/sdram/spd.c where all
> chipsets can use them.
>
> The SPD-only stuff should be chipset-independent, only the
> chipset-specific stuff should be handled in the respective raminit.c.
>

Uwe, This is for the intel 82830 chipset I have been working on. It is  
for raminit.c, it think it would be much eaisier to setup the DRB  
register if you could determine if the SDRAM module is single sided or  
double sided through SPD.

Thanks - Joe




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