Re: [microblaze-uclinux] DMA and cache

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi Jim,

Jim Van Vorst wrote:

> I'm using 2.6 currently.  Am I better off moving to 2.4 until this gets 
> fixed up?

Hard to say - I don't think there's a lot of work to get this going, 
it's just still in the queue.

> Also, does the u-boot or kernel build care about C_BANK0_HIGHADDR, or is 
> that
> just for the bitstream?

Hmm, good question.  I'd have to go digging.  The uncached shadow thing 
was a bit of a hack that I did in 2.4 to try to improve ethernet DMA 
performance (avoiding a big cache invalidate loop after receving each 
packet.

It got copied into 2.6 when lynuxworks hacked out the initial port, but 
I don't think it's ever been tested.

My advice is probably to stick with 2.6, and either debug/test the 
UNCACHED_SHADOW support as is, or put a dcache_invalidate call into your 
driver to make sure the cache is clean.

Regards,

John
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