ccd on NATA problem - ata0: FAILURE - oversized DMA transfer attempt 73728 > 65536

[YONETANI Tomokazu]

On Fri, Jul 20, 2007 at 10:12:33AM -0700, Matthew Dillon wrote:
> 
> :Ok, I tried the patched kernel, with a modification to ata-dma.c to
> :reduce max DMA size of the second channel to 16k.  ccd devices span
> :on these two channels, and one of them is used as /usr/obj and another
> :for /home.  I observed no errors during `make -sj3 buildworld'.  I also
> : tried to enlarge the stripe size from 1152 to 64k, but newfs barfed
> :on it (Invalid argument), so I could only use 65535.
> :
> :Cheers.
> 
>     Excellent.
> 
>     64k?  Those numbers are in sectors!  1152 = 576KB. 64K = 32MB stripe
>     size.   I'll check over the CCD code to see why the larger stripe
>     size didn't work, it should be something simple stupid.  Newfs should
>     have had no visibility into the stripe size.

This happens with unpatched kernel, too, and it's not limited to newfs.
 # hd /dev/ccd0s0a | less
displays the same error message, too.

>     Could you explain the modification you made to ata-dma.c to
>     reduce the max DMA size of the second channel?  Does your second
>     channel not work without that?  I'd like to see the patch too.

I made the modification only to see if ccd works with components
with different DMA I/O sizes.  It works with or without the modification.

>     I will commit the strategy fix now.

Thanks!