[Trac #151] 256 Meg RAM support

[Zarro Boogs per Child]

#151: 256 Meg RAM support
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 Reporter:  jg           |        Owner:  wmb at firmworks.com
     Type:  enhancement  |       Status:  assigned         
 Priority:  blocker      |    Milestone:  BTest-1          
Component:  linuxbios    |   Resolution:                   
 Keywords:               |  
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Comment (by wmb at firmworks.com):

 I made the change in my private tree and tested it on both a 128 MB Btest
 board and a 256 MB Btest board.  Both work.  On the 256M board, 256MB of
 memory (less that used by  SMM and video) is indeed available and
 accessible.

 The change was simple because the chips are high compatible.  The only
 significant difference is the number of column address bits.  The changed
 boiled down to changing two fields - DIMM0 Size and DIMM0 Page Size - in
 the MC_CF07_DATA MSR.  The code first reads the value of GPIO bit 2 to
 determine which values to use.

 I'm not going to release a new firmware image with this change today.
 Since I have the only 256 MB board, who would test it?

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Ticket URL: <http://dev.laptop.org/ticket/151#comment:5>
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