Re: [PATCH] Add support for usbfs zerocopy.

[Christoph Hellwig]

On Wed, Jan 06, 2016 at 03:45:12PM +0100, Steinar H. Gunderson wrote:
> On Tue, Jan 05, 2016 at 10:49:49PM -0800, Christoph Hellwig wrote:
> > This is a completely broken usage of the mmap interface.  if you use
> > mmap on a device file you must use the actual mmap for the data
> > transfer.
> 
> Really? V4L does exactly the same thing, from what I can see. It's just a way
> of allocating memory with specific properties, roughly similar to hugetlbfs.

V4l is generally speaking never an example for good practices.