ATA + DMA still giving repeatable freezes

Robert Watson rwatson at
Tue Jan 6 11:47:56 PST 2004

On Wed, 24 Dec 2003, Kirk Strauser wrote:

> At 2003-12-20T00:17:00Z, Robert Watson <rwatson at> writes:
> > FYI, I had this problem on a notebook and foudn that disabling "device
> > apic" made things clear up.  Try it and see if it helps, and if it does,
> > post as much.  I'm busy testing to make sure my observation is right on my
> > system.  I also saw fairly frequent hangs starting or leaving XWindows,
> > and John Baldwin hypothesized there was an interaction between DRM and the
> > interrupt code.
> Robert, I wanted to get in some more testing before reporting back.  I
> cvsup'ed again and built world and kernel.  This time, I started with
> plain GENERIC and made minor changes until I could reproduce the hangs. 
> Basically, commenting out "options WITNESS" and "options
> WITNESS_SKIPSPIN"  was enough to trigger the problem; I'm guessing that
> these options slow down the system enough that timing issues disappear. 
> After adding this to my /boot/loader.conf.local:
>     hw.ata.ata_dma="0"
>     hint.acpi.0.disabled="1"
> I no longer get system hangs, although I do get these messages at random
> intervals during heavy ATA IO:
>     ad0: TIMEOUT - READ_MUL retrying (2 retries left)
>     ata0: resetting devices ..
>     done

Not sure if you misread, but it looks like you're disabling ACPI rather
than apic (confusing, eh? :-).  I'm currently in a situation on my Dell
Notebook where leaving the new ACPI enable but "device apic" disabled
seems to get me to full functionality.  I discovered a BIOS upgrade on the
Dell web site, and need to try installing that to see if it helps.  I also
haven't tried plugging and playing DRI as yet. 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at      Senior Research Scientist, McAfee Research

More information about the freebsd-current mailing list