On Sat, 2006-06-03 at 17:14 +0200, Sietse Visser wrote: > I reported this before on the devel list, but there was no answer.
You might have better luck on the xen-users list.
> I am trying to use ivtv on a xen0 kernel.
> The module loads, everything works like tuning etc, except that video
> is stuttery - it is playing for about one second, stops half a second,
> and then plays again one second.
> On a non-Xen kernel, everything is fine.
>
> When loading the ivtv module, the following is reported
> in /var/log/messages (note the PCI-DMA messages):
> Jun 3 16:59:01 marvin kernel: PCI-DMA: Out of SW-IOMMU space for 5460
> bytes at device 0000:00:05.0
Xen dom0 always uses swiotlb and I think it defaults to a 2M region if
you have <2G RAM and 64M otherwise. There should be a message in dmesg
about it when it initialises.
IVTV must use a lot of DMA memory since it appears to be running out.
You can increase the amount of space reserved with e.g. swiotlb=32M on
the dom0 kernel command line.
You might also need to restrict the amount of memory given to dom0 in
the first place so there is more left over for DMA buffers. You can do
this by using the dom0_mem Xen command line option:
/*
* dom0_mem:
* If +ve:
* * The specified amount of memory is allocated to domain 0.
* If -ve:
* * All of memory is allocated to domain 0, minus the specified
amount.
* If not specified:
* * All of memory is allocated to domain 0, minus 1/16th which is
reserved
* for uses such as DMA buffers (the reservation is clamped to
128MB).
*/
Something like dom0_mem=-128M would be a good start I suppose.
Ian.
--
Ian Campbell
We don't care how they do it in New York.
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