Subject: Re: 2.6.37-git17 virtual IO boot failure

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 19 Jan 2011 17:06:18 +1100

On Tue, 2011-01-18 at 16:48 -0800, Nishanth Aravamudan wrote:
> 
> Ben, if you're ok with waiting to see if Milton or Sonny have any
> ideas,
> I'd like to hold off on asking for a revert. In the case they do, I'll
> be able to test and send out any proposed fix rapidly. 

I don't believe this specific error is causing the lockup, I think we
only hit a spurrious message on devices that don't have DMA capabilities
in the first place. (But I may be wrong, I'll wait for you guys to dig
more or I'll have a look myself tomorrow if I manage to get out of
meetings).

So there's another problem with SCSI tho it -could- also be a DMA issue,
hard to tell at this point.

BTW. I'm not too happy with those defaults set to 64-bit. Probably not
an issue until your other patches go in, but some devices like veth
cannot do 64-bit DMA. I think we should default to 32-bit in the VIO
base code and explicitely enable 64-bit DMA from drivers that support it
(in theory vscsi but I haven't verified the implementation).

Cheers,
Ben.