[Fwd: Re: ad2: FAILURE - READ_DMA, but CD on slave controller recognized?]

[Pertti Kosunen]

C. Fischer wrote:

>this has started bugging me ever since moving from 4-stable to 5-stable.
>"ad2", which had been recognized no problem on the former, fails on the
>latter.  since i have a multibooter, i can boot 4.10 residing on "ad2" without
>trouble.  4.10 can access "ad0" and "ad1" fine (this is how i got the initial
>install in place), but i used "ad2" for backups and this doesn't work anymore.
>
>the system otherwise works and there are no DMA related hardware errors ever
>reported except for "ad2" not beeing recognized.  this seems to indicate that
>the problem lies in the initial disk checking phase.

It's pretty common problem with 5.3, one solution is to:

Disable DMA for boot.
cat /boot/loader.conf
hw.ata.ata_dma="0"
hw.ata.atapi_dma="0"

And enable first channel DMA later.
cat /etc/rc.local
atacontrol mode 0 udma4 udma4

http://lists.freebsd.org/pipermail/freebsd-stable/
Searchs previous messages for other workarounds. Disabling APIC might help.