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Altera_Forum
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21 years ago

uClinux .data segment in SDRAM?

For a number of reasons, I'd like to run my kernel in SRAM but allocate data memory (i.e. socket buffers) in SDRAM. This seems possible with a NIOS 'Hello World' application, or the like...
Altera_Forum's avatar
Altera_Forum
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21 years ago

Thanks Wentao, your second idea sounds perfect.

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Can you tell me what problem you foresee?[/b]

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The only real problem I saw with modifying the kernel was the fact that I&#39;m no kernel expert, and it _basically_ works now http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif . But your explanation definitely seems simple enough.

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Currently the DMA zone is empty, you can put all your sdram into that zone and just remember to specify GFP_DMA when your driver wants memory.[/b]

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From cursory inspection of init.c -- where exactly can I tell the kernel that ZONE_DMA begins at 0x0? I see in paging_init where to specify size -- and it works, but gives me chunks of SRAM right now -- I just can&#39;t find where the zone structure offsets are defined.

Thanks again for all the help,

Ryan