How to use the DMA Engine in FreeBSD?

[Hans Petter Selasky]

On 12/13/18 11:04 AM, Rajesh Kumar wrote:
> Hi,
> 
> Is there any good documentation available to understand the existing
> support, API's and how-to use the DMA Engine in FreeBSD?
> 
> I am trying to write a test driver which will use DMA Engine to do the data
> transfer (rather than plain memcpy which involves cpu).  Can anyone point
> to any driver implementation which has similar functions implemented?  I
> see references to SYS_RES_DRQ to allocate DMA channels and play around. But
> that seems to be specific to ISA. Can it be used for PCI drivers as well?

Hi,

What you are looking for is called PCI busmaster.

--HPS