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Re: [Xen-devel] Xen linux error message: PCI-DMA: Out of SW-IOMMU space

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Xen linux error message: PCI-DMA: Out of SW-IOMMU space for 65536 bytes at device 0000:02:01.0
From: Muli Ben-Yehuda <muli@xxxxxxxxxx>
Date: Sun, 9 Sep 2007 08:21:55 +0300
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Stefan Berger <stefanb@xxxxxxxxxx>, xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
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On Sat, Sep 08, 2007 at 09:57:40AM +0100, Keir Fraser wrote:
> On 7/9/07 20:01, "Stefan Berger" <stefanb@xxxxxxxxxx> wrote:
> >> > You can change to e.g., a 128MB swiotlb by putting ?swiotlb=128¹ on
> >> > you dom0 cmdline.
> > 
> > Not that I find this a good or intuitive solution, but at least now the 
> > error
> > messages have disappeared. Couldn't this swiotlb grow automatically when
> > needed? 
> No, it is allocated at boot time, and creating a larger one by
> default would waste memory on most systems.

I've been toying with the idea of dynamically allocating the swiotlb
aperture to handle cases like this, but the added run-time cost and
complexity may not be worth it for what is supposed to be a


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