hw.ata.atapi_dma in 5.4-RELEASE-p1

Michael Nottebrock lofi at freebsd.org
Sun May 22 10:34:26 PDT 2005

On Sunday, 22. May 2005 17:29, Janet Sullivan wrote:
> I am unable to get my DVD or CD drives out of PIO4 mode on two machines.
>   One has an ICH3 controller, the other is Nforce2 based.
> When I put hw.ata.atapi_dma="1" in /boot/loader.conf and reboot, I'm
> still stuck in PIO4.  What am I doing wrong?

The drives probably don't support any UDMA modes. WDMA modes aren't enabled 
for atapi devices because there's a very large number of devices which don't 
implement them right or not at all, yet claim to support them.

You can enable whatever DMA modes those drives support with the atacontrol 
utility after the kernel has booted up.

   ,_,   | Michael Nottebrock               | lofi at freebsd.org
 (/^ ^\) | FreeBSD - The Power to Serve     | http://www.freebsd.org
   \u/   | K Desktop Environment on FreeBSD | http://freebsd.kde.org
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