Why is ATAPI DMA disabled by default ?

[Soeren Schmidt]

It seems Maxim Konovalov wrote:
> 
> > I use 5.1-current and have found that by default FreeBSD disables ATAPI's
> > support for DMA transfers and thus uses CPU hungry PIO modes.
> > It even makes sysctl used to change this read-only.
> > I had changed the default value of atapi_dma to 1 in dev/ata/atapi-all.c to 1
> > and it worked fine for me.
> 
> Hint: put hw.ata.atapi_dma="1" in /boot/loader.conf.

Or just use atacontrol to change the mode once the system is running...

-Søren