From: Andi Kleen <ak@suse.de>
To: Jens Axboe <axboe@suse.de>
Subject: Re: PCI-DMA: Out of IOMMU space on x86-64 (Athlon64x2), with solution
Date: Thu, 2 Mar 2006 15:35:35 +0100
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On Thursday 02 March 2006 15:14, Jens Axboe wrote:

[...]

Ok great we agree on everything then.

> > > 
> > > I would not want to call wake_up() unless I have to. Would a
> > > 
> > >         smp_mb();
> > >         if (waitqueue_active(&iommu_wq))
> > >                 ...
> > > 
> > > not be sufficient?
> > 
> > Probably, but one would need to be careful to not miss events this way.
> 
> Definitely, as far as I can see the above should be enough...

Ok - you just need to give me a wait queue then and I would be happy
to add the wakeups to the low level code

(or you can just do it yourself	if you prefer, shouldn't be very difficult ... - just
needs to be done for both swiotlb and GART iommu. The other architectures
can follow then. At the beginning using an ARCH_HAS_* ifdef might be a good
idea for easier transition for everybody) 

-Andi
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