[uClinux-dev] I/O from userspace

Greg Ungerer gerg at snapgear.com
Wed Nov 24 19:23:23 EST 2010

Hi Philip,

On 23/11/10 08:27, Philip Nye wrote:
> I'm trying to port some applications from an old kernel 2.4.x project to
> an up-to-date kernel 2.6.x build - all running on Coldfire with no MMU.
> One of these applications accesses some coldfire IO registers directly
> from userspace and it doesn't seem to be working after the port.
> Is it still the case that on a m68knommu system it is possible to simply
> read or write anywhere from userspace? or has some rudimentary
> protection been implemented?

Which ColdFire part are you using?

Although the kernel doesn't specifically limit userspace accesses
some ColdFire parts have "System Access Control Units" or similar
mechanisms for limiting/protecting acceses. (I know the 523x parts
have one for example).

It could just be that this is/was set in the 2.4.x code and is not
set the way you want in the 2.6.x code.


Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

More information about the uClinux-dev mailing list