bus_dmamem_alloc strangeness

[Mike Silbersack]

On Thu, 17 Feb 2005, Gerald Heinig wrote:

> Hi hackers,
>
> I've come across weird behaviour in bus_dmamem_alloc() whilst trying to
> allocate small memory blocks (less than PAGE_SIZE) which have to be
> aligned to PAGE_SIZE.
> My segment size is 2048, my maximum number of segments is 1 (it MUST be 
> contiguous), my max. total segment size is also 2048 and my alignment 
> constraint is 4k (PAGE_SIZE). However, the DMA memory I'm getting from 
> bus_dmamem_alloc() is NOT aligned to 4k.

You should e-mail Scott Long (scottl at freebsd.org) about this directly.  I 
believe that he has been working on related changes to busdma recently, 
but I'm not sure which branches have received his improvements.

Mike "Silby" Silbersack