Re: [microblaze-uclinux] Need some pool memory

[George Smith <gesmith@xxxxxxxxxxxxxxxxxx>]

hi
  The linux.ld script has 0x02000000 as the length. So the memory size
didn't get there...


 I'm using the older bsp and tools so  MAIN_MEMORY_OFFSET is ignored in
my BSP package. 

 I'm going to add a uncached address attribute to my sdram controller...

Thanks
gesmith

On Wed, 2005-11-16 at 21:22, John Williams wrote:
> Hi George,
> 
> George Smith wrote:
> 
> >  I need some "pool" memory - memory that linux won't touch and I can use
> > external dma into it. So I tried the: 
> >  PARAMETER MAIN_MEMORY_SIZE = 0x01f00000
> >  in my system.mss. 
> > 
> > That sets auto-config.in:
> > # MAIN_MEMORY Settings
> > define_hex CONFIG_XILINX_ERAM_START 0x80000000
> > define_hex CONFIG_XILINX_ERAM_SIZE 0x01f00000
> 
> How much memory does the kernel report in the boot log?
> 
> > Which seems to me that linux would not touch about 
> > 0x81efffff (or mod 4 of that).
> > But when uclinux comes up I find memory from there up to the 32MB
> > boundry has been painted with zeros. 
> 
> Hmm..  I wonder if it's not a power-of-two issue in the initial boot mem
> allocator.
> 
> > So the question is how to get pool memory. Have I done something
> > incorrect? Should I place it at the bottom of memory, which was the
> > standard back in the old unix days??
> 
> You could try the MSS parameter MAIN_MEMORY_OFFSET that is supported in
> recent versions of the uClinux BSP packages
> 
> MAIN_MEMORY_OFFSET = 0x100000
> MAIN_MEMORY_SIZE = 0x1F00000
> 
> see if that works any better.
> 
> John
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-- 
George Smith
VP Engineering
Linear Acoustic, Inc

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