svn commit: r188350 - in head/sys: amd64/amd64 arm/arm dev/usb2/core i386/i386 ia64/ia64 sys

[John Baldwin]

On Monday 09 February 2009 12:37:53 am Marcel Moolenaar wrote:
> 
> On Feb 8, 2009, at 5:00 PM, Scott Long wrote:
> 
> > Busdma allows you to request bouncing for realignment.
> 
> How exactly?

The 'align' parameter to bus_dma_tag_create().  If your hardware needs buffers 
to be aligned on a 4-byte boundary and you bus_dmamap_load() a buffer 
where 'addr % 4 != 0', then the buffer is bounced.  Since by default the new 
buffer starts on a page boundary, it satifies the 'addr % 4'.

-- 
John Baldwin