> -----Original Message----- > From: [email protected] [mailto:iommu- > [email protected]] On Behalf Of Damian Hobson-Garcia > Sent: Thursday, January 17, 2013 8:51 AM > To: Alex Williamson > Cc: [email protected]; [email protected]; > [email protected]; [email protected] > Subject: Re: [RFC] drivers: iommu: Use of add_device()/remove_device() > outside of IOMMU groups > > I mistakenly sent this with the tag [PATCH] when it should have been > [RFC]. Updated with this reply. > > Hi Alex, > On 2013/01/17 6:47, Alex Williamson wrote: > > On Tue, 2013-01-15 at 19:10 +0900, Damian Hobson-Garcia wrote: > >> We've recently been thinking about the best way to attach platform > >> devices in an IOMMU in a generic way without having to have every > >> platform device register itself at probe time. We've seen that at > >> least on the tegra IOMMU, using the platform_bus notifier seems like > >> a viable option > >> (http://lists.linuxfoundation.org/pipermail/iommu/2012-December/00495 > >> 4.html). We also noticed that the IOMMU ops add_device() function is > called (indirectly) from a similar bus notifier and we're thinking that > using the bus notifier in the common code would be better than us rolling > our own to do basically the same thing. > >> > >> The problem, however, is that add_device() seems to be intended for > >> use with IOMMU groups. i.e. After calling add_device() on a device > >> that is should be in a group, dev->iommu_group should have some > meaningful value. > >> I think though, that if the IOMMU groups requirement can be removed, > >> it should be more versatile. > >> > >> I believe that removing the IOMMU groups dependency can be achieved > >> with the patch below. Currently the intel-iommu seems to be the only > >> implementation using these callbacks. > > > > What stops you from creating a single iommu_group and adding all > > device to it? Thanks, > > > > Alex > Thanks for your comment. > > Nothing stops me, but putting everything in one group doesn't really add > any benefit over not using groups at all, does it? It seems like its > just adding more complexity(i.e code) to the driver without adding any > additional functionality. > Do you intend to use vfio? That's the specific objective of creating iommu groups.
-Varun _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
