WDMA mode won't enable? Old machine...

[Nathan Kinkade]

On Tue, Oct 19, 2004 at 10:18:18PM +0100, Mark Cullen wrote:
> I have a rather old machine acting as a home server. According to dmesg 
> it has a:
> 
> --
> atapci0: <Intel PIIX WDMA2 controller> port 
> 0xffa0-0xffaf,0x376,0x170-0x177,0x3f6,0x1f0-0x1f7 at device 7.1 on pci0
> --
> 
> However, both hard disks attached are running in PIO mode.
> 
> --
> ad0: 4103MB <ST34321A> [8894/15/63] at ata0-master BIOSPIO
> ad2: 6194MB <IBM-DADA-26480> [13424/15/63] at ata1-master BIOSPIO
> --
> 
> I tried running the following, but as you can see the end result is that 
> they are still running BIOSPIO.
> 
> --
> (root|bone)/home/mrboo# atacontrol mode 0 WDMA2 WDMA2
> Master = BIOSPIO
> Slave  = BIOSPIO
> --
> 
> Any suggestions as to how I might enable some sort of DMA on these 
> drives? Since the machine is rather slow (133MHz) and it's currently 
> using polled IO I am sure it will likely benefit me, even if it isn't 
> quite UDMA :)

You should check out the following sysctl variables:

hw.ata.ata_dma
hw.ata.atapi_dma

These are readonly at runtime, so need to be set at boot in the file
/boot/loader.conf.  You can add the them like so:

hw.ata.ata_dma=1
hw.ata.atapi_dma=1

Also, as I understand it, 80 conductor ribbon cables were only
recommended at UDMA modes <=2, but perhaps you might consider using one
just to be safe.

Nathan
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