Re: [PATCH 01/13] driver core: Add iommu_group tracking to structdevice

From: Alex Williamson
Date: Fri May 11 2012 - 19:58:28 EST

On Fri, 2012-05-11 at 16:38 -0700, Greg KH wrote:
> On Fri, May 11, 2012 at 04:55:35PM -0600, Alex Williamson wrote:
> > IOMMU groups allow IOMMU drivers to represent DMA visibility
> > and isolation of devices. Multiple devices may be grouped
> > together for the purposes of DMA. Placing a pointer on
> > struct device enable easy access for things like streaming
> > DMA programming and drivers like VFIO.
> >
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Can't you get this today from the iommu_ops pointer that is on the bus
> that the device is associated with? Or can devices on a bus have
> different iommu_group pointers?

The latter, each device on a bus might be it's own group. This is often
the case on x86 unless PCIe-to-PCI bridges obscure the device
visibility. Thanks,


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at