[microblaze-uclinux] DMA and cache

[Jim Van Vorst <jvanvorst@xxxxxxxxx>]

I found an old thread about the

> #if CONFIG_XILINX_UNCACHED_SHADOW
> 	ret = (void *)((unsigned) ret | UNCACHED_SHADOW_MASK);
> #endif

trick so scatter-gather DMA can play nicely with caching.
What is the current status of this?  I saw at least one FIX ME note
in the related code.

From what I understand, if my ram is 64 megs from 0x3000.0000 to 0x33ff.ffff,
when the network driver needs to allocate dma buffers it will get a range
from 0x3400.0000 to 0x37ff.ffff which is our of my cached range (assuming
I'm caching all of ram).  Is this correct?  Is there some value I have to
change in the .mhs file to fake out 128 megs?

I'm asking because I can't get scatter-gather to work.  I dies somewhere
in the descriptor_init() function.

Thanks,
Jim

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