Query Hard Memory Addresses

[Greg KH]

On Thu, Oct 22, 2015 at 03:13:31PM -0400, Kenneth Adam Miller wrote:
> So, previously it was discussed that /dev/mem could be used to mmap a specific
> hardware memory into a process. Now I need to unit test some userland code that
> does exactly that, but I need to make sure that the unit test selects a small
> page that is always free in kernel land. How can I query mem to just grab the
> location of a free page?

You can't know this from userspace, and even if you could, what would
guarantee that 1 second later the kernel wouldn't grab that page to do
something else with it?

sorry,

greg k-h