Messages in this thread | | | Date | Mon, 28 Sep 2009 22:37:27 +0200 | From | Alejandro Riveira Fernández <> | Subject | Re: Disabling DMA with ICH10? |
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El Mon, 28 Sep 2009 23:31:21 +0200 Lennart Baruschka <FunFlyer@gmx.net> escribió:
> Hello, > > I'm new to this list, so please forgive me if this is the wrong place to > ask. I'm trying to build a 2.6.30.5 kernel causing as little DMA traffic > as possible in order to reduce latencies on a real-time system (using > RTAI). > > 1. Is there a way to completely disable DMA usage system-wide? > If not: > 2. My system uses an ICH10 chipset, the harddrive is connected to the > Intel SATA controller. Is there a way to disable DMA and switch back to > PIO? I tried compiling with libata support and without SCSI support, but > the kernel is unable to mount root (no matter if /dev/sda1 > or /dev/hda1), then.
AFAIK libata needs scsi support. To disable dma in libata I get from Documentation/kernel-parameters.txt --> libata.dma = 0
> 3. Another source seems to be the ATL1E driver for ethernet. Is it > possible to either disable DMA for this?
That I dunno
> > If disabling DMA is impossible for some reason for one or both drivers, > is it at least possible to reduce the burst sizes so the bus gets free > for a short time during which I could access it from my real time kernel > module? > > Please point me in the right direction; any suggestion will be greatly > appreciated! > > Cheers, > Lennart
Saludos, Alejandro
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