DMA

Panagiotis Issaris panagiotis.issaris at mech.kuleuven.ac.be
Sun Oct 17 17:36:35 CEST 2004


Hi,


On Sat, Oct 16, 2004 at 03:00:31PM -0700 or thereabouts, MJ_RT wrote:
> Hi Panagiotis.
> How I can Disable DMA in Linux? I can't find it in menu-config Linux
> installation. It is need or optional (I do any think that explained in
> installation manual).
By using "hdparm" you can check whether DMA is enabled, and disable it.

For example:

* To show information about your harddrive:
  /sbin/hdparm /dev/hda

* To disable DMA for the first IDE controller master disk:
  /sbin/hdparm -d0 /dev/hda

The Linux kernelconfiguration does give you the option of compiling
in DMA support -both in general and for specific IDE controllers- or 
leaving it out.

> Once I installed RTX5 demo in XP on my PC, it's test shows less than 7
> us latency with my poor hardware that has 2ms latency in RTAI! Who this
> can happen?
Check that you also disabled powermanagement in the Linux kernel configuration.

 
> Please guide me to good reference.
> 
> Excuse me for simple question, I am new to RTAI.
> Regards.

With friendly regards,
Takis

-- 
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Panagiotis Issaris
Katholieke Universiteit Leuven
Division Production Engineering,
Machine Design and Automation
Celestijnenlaan 300B              panagiotis.issaris at mech.kuleuven.ac.be
B-3001 Leuven Belgium                 http://www.mech.kuleuven.ac.be/pma
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