Share your knowledge at the LQ Wiki.
Go Back > Forums > Linux Forums > Linux - Newbie
User Name
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!


  Search this Thread
Old 07-30-2009, 12:56 AM   #1
LQ Newbie
Registered: Jul 2009
Posts: 29

Rep: Reputation: 0
Making memory uncacheable for a linux kernel module

I'm facing an issue regarding making certain memory
uncacheable when using a linux kernel module.

Here's a brief description of what I'm doing.
Thereís a shared memory between the arm processor(ARM926EJ-S) and an
ASIC. Both processor (kernel module) and asic read and write to this
memory. When asic writes to this memory, say location 0xff00, the
contents of this location are read by arm processor from its cache
instead of from the memory.
Iím trying to make sure processor always reads from memory instead of reading invalid data from its cache.
So I tried using ioremap_nocache to make the whole shared memory as
uncacheable. Though this function returned non-null (signalling a successful return), I found that processor was still reading stale data
from its cache.

My linux version details are as under.

Linux version (root@demo) (gcc version 4.2.1) #1 Thu Jun 25 11:50:35 PDT 2009
Ubuntu 9.04 \n \l

Linux Debian 5.0 ( armv5tejl)

I would like to know if there's a bug in ioremap_nocache for this
particular linux kernel version for the given ARM processor or
there is any other assured way of making memory uncacheable.

Thanks in advance,


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Kernel & Kernel-module memory Usage ascetic angel Linux - Kernel 1 09-14-2008 09:30 PM
POSIX Shared Memory w/ Kernel Module Smoltz Linux - Kernel 0 08-12-2008 02:56 PM
Making kernel module yannifan Programming 1 02-04-2007 09:00 AM
dynamic memory allocation in kernel module appas Programming 4 09-21-2004 07:36 AM
Allocating memory for user program variable from kernel module appas Programming 2 08-12-2004 11:52 PM > Forums > Linux Forums > Linux - Newbie

All times are GMT -5. The time now is 12:58 PM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration