Re: Using both memory banks for 256Mb DRAM in AT91SAM9G45

[Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>]

On Mon, Sep 14, 2009 at 04:19:14PM +0200, Sedji Gaouaou wrote:
> Hi,
>
> I've posted a mail with quite the same problem.
> I am working on a board with 2 32M SDRAM at 0x70000000 and 0x90000000,  
> and I don't know how can I declare/access the second SDRAM.
> I tried to add a fixup function in MACHINE_START, but it fails in the  
> function "build_tag_list returning:
> "Warning: bad configuration page, trying to continue"
>
> BTW I have no bootloader since I load my kernel and rootfs with AXD.
>
> Is it the proper way to declare a second bank of memory?
> What am I missing?

mem=32M@0x70000000 mem=32M@0x90000000

If using the standard flatmem memory model, be sure that:

(a) you aren't going to mmap any physical address between these two RAM
    banks without my pfn_valid() patch.
(b) that you have 32MB at 0xc0000000 and 32MB at 0xe0000000 available,
    and nothing mapped between 0xc0000000-(0xe0000000+32M)

Alternatively, use sparsemem, and define NODE_MEM_SIZE_BITS in
your mach/memory.h to be a value between 25 and 29 inclusive.
(29 would seem to make the most sense.)

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