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Accessing DDR DCR registers in init_mem - PMC RM9000

Subject: Accessing DDR DCR registers in init_mem - PMC RM9000
From: Sean Parker <>
Date: Mon, 14 Jul 2008 06:23:49 -0700 (PDT)
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Hello - 

  We're trying to determine dynamically the DDR DCR register values from within 
setup.c, init_mem(), so that we can remove the hard-coded 256MB RAM size (and 
not rely on cmd-line args) From documentation I've read (not evry clear for a 
MIPS newbie) it appears I need to setup a TLB entry to access phys mem above 
0x80000000. (PMON already sets up a range for Compact Flash)

  I setup a TLB entry for that region ( 0xFF080000, making 3 total entries 
setup in PMON) but I still get an exception in setup.c when I try to read the 
DCR reg.

  Is it as simple as setting up a TLB entry? I can't find examples for how to 
access registeres in various segments of physical memory (in kernel mode) does 
anyone know of a good resource for that kind of stuff?

  Any suggestions?



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