Re: [Xen-devel] [PATCH 2/2] arm/xen: Don't use xen DMA ops when the device is protected by an IOMMU

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

CC'ing Greg.

On Thu, 20 Feb 2014, Ian Campbell wrote:
> On Thu, 2014-02-20 at 16:21 +0000, Julien Grall wrote:
> > Only Xen is able to know if a device can safely avoid to use xen-swiotlb.
> > This patch introduce a new property "protected-devices" for the hypervisor
> > node which list device which the IOMMU are been correctly programmed by Xen.
> > 
> > During Linux boot, Xen specific code will create an hash table which
> > contains all these devices. The hash table will be used in need_xen_dma_ops
> > to check if the Xen DMA ops needs to be used for the current device.
> 
> Is it out of the question to find a field within struct device itself to
> store this e.g. in struct device_dma_parameters perhaps and avoid the
> need for a hashtable lookup.
> 
> device->iommu_group might be another option, if we can create our own
> group?

I agree that a field in struct device would be ideal.
Greg, get_maintainer.pl points at you as main maintainer of device.h, do
you have an opinion on this?

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