kernel driver access application memory

[Mandeep Sandhu]

On Wed, Jan 15, 2014 at 11:45 PM, m silverstri <
michael.j.silverstri at gmail.com> wrote:

> Hi,
>
> If my application allocate memory for input and output buffers,  and
> pass the pointer to a kernel driver (via v4l2 queue buffer operation),
> can the kernel driver access it? Do I need to setup DMA before teh
> kernel driver can read/write to it?
>

You can transfer data to & from kernelspace/userspace by using
copy_to/from_user() API.

However, for DMA I think you might also want to lock the user pages in
memory so that they are not invalidated when the owning process is
scheduled out. This is a very high-level gist, but there a lot of resources
out there which show how this can be done.

HTH,
-mandeep



>
> Thank you.
>
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