Thread (4 messages) 4 messages, 3 authors, 2005-03-24

Re: question about writing to memory directly from user space in Linux

From: Stefan Nickl <hidden>
Date: 2005-03-24 07:44:14

On Wed, 2005-03-23 at 09:10 -0800, Eugene Surovegin wrote:
On Wed, Mar 23, 2005 at 10:46:45AM +0100, Stefan Nickl wrote:
quoted
On Wed, 2005-03-23 at 14:25 +0530, Vijay Padiyar wrote:
quoted
Can you suggest some kind of a "synchronization" function which I can call
from *user space* which will ensure that all values written to mmaped memory
locations from user space are actually flushed to their physical locations?
I think this might be a potential problem with my code.
Have a look at linux/include/asm-ppc/{io.h,system.h} and
http://www.xml.com/ldd/chapter/book/ch08.html

The eieio instruction doesn't need supervisor rights.
eieio is a nop on 603e core.
Interesting, I was not aware of this.

eieio is handled differently between MPC8245 and MPC8260.

Anyways, it's a non-issue as IO memory should have the right WIMG bits
set to take care of this, and modelling it with a in-kernel i2c bus as
suggested on the list is soo much nicer.

-- 
Stefan Nickl
Kontron Modular Computers
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