Subject: Re: SCSI Scatter-Gather buffer command
To: Dante Profeta <dante@mclink.it>
From: Jason Thorpe <thorpej@nas.nasa.gov>
List: tech-kern
Date: 07/02/1998 10:59:41
On Thu, 02 Jul 1998 14:02:01 +0200
Dante Profeta <dante@mclink.it> wrote:
> Jason Thorpe wrote:
> > Is that as clear as mud? :-)
>
> :-) It's very clear to me, thank you.
*whew* Ok, good ... sometimes it's hard to explain things (you take for
granted background info that the other person might not know...)
> There is no such a thing in my Linux code.
> So, have I to translate linear buffers into DMA segments? Why?
Well... because linear buffers in virtual space are not necessary
linear in DMA space...
In any case, it's easy... you call bus_dmamap_load() with the linear
buffer, and it places the DMA segments into the dmamap... the code
in bha.c that does this is in bha_scsi_cmd(), starting at line 1450
(assuming version 1.23 of the file).
Jason R. Thorpe thorpej@nas.nasa.gov
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