On Jun 28, 2006, at 12:06 PM, Manuel Bouyer wrote:

> On Wed, Jun 28, 2006 at 11:51:31AM -0700, Jason Thorpe wrote:
>>
>> On Jun 28, 2006, at 10:50 AM, Manuel Bouyer wrote:
>>
>>>> Only do this if you vslock the buffer!
>>>
>>> When calling uvm_vslock(), do we also need to PHOLD() the process ?
>>
>> You only need to PHOLD if you going to do DMA to/from the stack.
>
> The kernel stack, I guess ?

Right.


> So to do dma from/to a user-supplied buffer
> only uvm_vslock() is needed, right ?

Right.  Also, make sure you never load in interrupt context (because  
you have to lock the user's pmap to extract the physical addresses.)

>
> -- 
> Manuel Bouyer <bouyer@antioche.eu.org>
>      NetBSD: 26 ans d'experience feront toujours la difference
> --

-- thorpej