Subject: Re: mmap() of device
To: Robert Black <>
From: Chris G. Demetriou <>
List: tech-kern
Date: 08/05/1997 16:46:19
> I need to map some physical pages controlled by a device driver into user
> space. The obvious way to do this is to use the mmap entry point, however I
> need to be able to forcibly change this mapping (to a different area of memory)
> from the driver at a later time. The mmap interface does not seem to be
> flexible enough to achieve this so I guess I am going to have to use an ioctl.
> Any comments/suggestions?

The first thing that comes to mind is the old standby: Why do you
think you want to do this?

Other ports have used ioctls which map device space in the past, and
over time they've only caused problems.  What is your so-special
application that it needs to change user mappings under their noses?