Re: Triton DMA

[John Looney]

Ar Fri, Nov 28, 1997 at 07:32:26PM -0500, scriofa linux kernel account:
> On Fri, 28 Nov 1997, mlord wrote:
> > Linux currently does not include full support for UDMA
> > (need to add CRC checking and error handling to do a proper job),
> > so it does not use DMA by default in your case.
> Wow, wait a sec here.. 
> With proper udma support will linux have to compute a crc32 of every block
> transfered???? Are there other stupid things like this with ide? No wonder
> IDE is such a damn cpu eater!

 No. From what I gather, the CRC computation is in hardware, however, the
"proper UDMA support" will have to check a CRC failed bit in a IDE register
to make sure the last block transferred correctly. It's not much of an
overhead, and would probably be the same as the check for the parity bit
currently done..

John

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