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Re: Linux Boot RAM Determination

Subject: Re: Linux Boot RAM Determination
From: Florian Fainelli <>
Date: Tue, 17 Jun 2008 20:15:43 +0200
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Hello Sean,

Le Tuesday 17 June 2008 19:45:01 Sean Parker, vous avez écrit :
> Hello -
>   We're developing a PMC-Sierra RM9000 system, and when Linux boots it
> seems to only see 256M RAM (cat /proc/meminfo -> MemTotal=256M), despite a
> Crucial 1GB double-sided SODIMM card.
>   The boot code is PMON, and it recognizes all 1GB (dimm0:2 Ranks each
> 512MB) and prints as much when it's done.
>   Is there a setting in the Linux source (we're using a single elf image
> with ramfs integrated) that might be limiting the MemTotal/RAM size found
> by Linux? I couldn't find anywhere in the Linux code (patched by PMC) that
> mentions reading the DDR DCR's to inspect what the configured RAM
> sizes/offsets are. Any ideas?

Did you check the code which reserves memory for ther kernel ? Most boards 
will set this in either prom or setup code :

pmc-sierra/msp71xx/msp_prom.c:          add_memory_region(base, size, type);
pmc-sierra/yosemite/setup.c:    add_memory_region(0x00000000, 0x10000000, 

If your code is based on yosemite, it seems like it should get the memsize 
parameter from the bootloader, instead of hardcoding it to 256Mb like it 
currently does.

Hope it helps you.
Cordialement, Florian Fainelli

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