That was what I was based my code on :-)
I assume it works ok for frame buffers as reading from them doesn't
cause any harm. The kernel never looks at what data it gets, so as
long as the device can honour a read of the first word in each page
all is OK. The problem comes when we mmap a device which gets upset at
having its memory gratuitously read like this.
Surely there are other devices out there that are sensitive to
unexpected reads?
Andrew