Subject: Re: On the subject of bus_dma(9) (fwd)
To: Matthew Jacob <>
From: Jason R Thorpe <>
List: tech-kern
Date: 03/07/2001 11:18:06
On Wed, Mar 07, 2001 at 10:51:33AM -0800, Matthew Jacob wrote:

 > I think documenting this as:
 > 	If you want to allocate memory that can be mapped without
 > 	the BUS_DMA_COHERENT, use malloc(9) and perform the usual
 > 	bus_dma_map and bus_dma_load functions. Note that you may
 > 	not be able to, in all cases, create a completely byte-coherent
 > 	view of this memory whilst it is mapped for device and CPU
 > 	access at the same time.

No, that would be wrong.  malloc(9) does not allocate DMA safe memory
(e.g. it could allocate memory that contains more than the allowed
number of DMA segments).

Give me a few minutes to digest some of the Solaris stuff, and I'll send
another piece of mail.

        -- Jason R. Thorpe <>