ad0 READ_DMA TIMEOUT errors on install of 7.0-RELEASE

Julian H. Stacey jhs at
Sun Mar 2 19:29:27 UTC 2008

Jeremy Chadwick wrote:
> On Wed, Feb 27, 2008 at 01:20:50PM -0700, Scott Long wrote:
> > I'd like to attack these driver problems.  What I need is to spend a
> > couple of days with an affected system that can reliably reproduce the
> > problem, instrumenting and testing the driver.  I have a number of
> > theories about what might be going wrong, but nothing that I'm
> > definitely sure about.  If you are willing to set up your system with
> > remote power and remote serial, and if we knew a reliable way to
> > reproduce the problem, I could probably have the problem identified and
> > fixed pretty quickly.
> Scott, I just wanted to take a moment to publicly thank you for stepping
> up to the plate on this one.  I have a feeling that most of these
> reports will have to be dealt with on a case-by-case basis, but despite
> that, I really do apprecaite you offering to take this one.  Thank you
> very, very much.
> In regards to my experience with said problem, I haven't been able to
> reproduce the errors I saw on January 25th:
> I do need to get the box in question into our datacenter and set up our
> remaining dev/test box to do nothing but hard I/O between ZFS and UFS
> for hours (or days) on end to see if I can reproduce it.  There's an
> entry in the FreeBSD ZFS wiki about this problem, but there's a
> possibility the issue I saw is different than what another user reported
> (his result was a panic, my result was a machine that locked up hard
> after letting FreeBSD report DMA errors for some time).  That user's
> post is here:

I have 2 laptops running 7
that wont boot without 
	/boot/loader.conf hw.ata.ata_dma="0"

> If you are willing to set up your system with remote power and remote serial
Sorry, I can't offer that easily
	( Would need to remove laptop battery, move laptop
	  & UPS to another site, set up serial of UPS to a net
	  server & prob v. little to no chance of BIOS & serial console)
I could easily test any patches though, made against 7.0-stable
(sorry no current partition on there currently - small disc.)

Julian Stacey: BSDUnixLinux C Prog Admin SysEng Consult Munich
	Mail just Ascii plain text.  HTML & Base64 is spam.

More information about the freebsd-stable mailing list