Reading from physical addresses..

[Aaron J. Grier]

On Thu, May 01, 2003 at 11:24:29PM -0400, Shailesh Hingole wrote:

>  I need to read from a range of physical addresses (for ex.
> 0x000-0x1000) from an application in RTEMS. When I say that, these are
> the actual locations on the physical memory and not on the process
> address space. 

RTEMS is designed for use in embedded environments which may or may not
have memory protection available, and assumes a flat memory map.  on
systems with MMU hardware, some minimal memory protection may be
applied, but there's no virtual memory or per-process memory spaces on
any RTEMS targets as far as I am aware.

I run on MMU-less m68k hardware; perhaps someone else here with more
advanced processor can volunteer more specifics?  ;)

> What is the best way to do it?

this depends on your application...  you could abstract the memory space
and make a formal device driver, or have RTEMS ignore it entirely and
just bang the hardware directly.

> Is it possible to do it from an application?

yes.  the question you need to answer is how far you want to abstract
the memory accesses.

what target hardware you are considering running RTEMS on?

-- 
  Aaron J. Grier  |   Frye Electronics, Tigard, OR   |  aaron at frye.com