Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Mar 05, 2026 at 03:26:14PM -0800, Jacob Pan wrote:
> Hi Jason,
> 
> On Fri, 27 Feb 2026 20:35:40 -0400
> Jason Gunthorpe <jgg@nvidia.com> wrote:
> 
> > On Sat, Feb 28, 2026 at 08:18:41AM +0800, kernel test robot wrote:
> > > Kconfig warnings: (for reference only)
> > >    WARNING: unmet direct dependencies detected for IOMMU_PT_AMDV1
> > >    Depends on [n]: GENERIC_PT [=y] && IOMMU_PT [=y] &&
> > > !GENERIC_ATOMIC64 [=y] Selected by [y]:
> > >    - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]  
> > 
> > Some kconfig stuff is missing, the iommufd IOMMU would only work with
> > GENERIC_ATOMIC64
> I don't quite understand this dependency on GENERIC_ATOMIC64, or you
> mean the opposite? since we currently have:

Oh, right the inverse.

> config IOMMU_PT_AMDV1
> 	tristate "IOMMU page table for 64-bit AMD IOMMU v1"
> 	depends on !GENERIC_ATOMIC64 # for cmpxchg64
> 
> And I already have noiommu depends on AMDV1 for mock page tables.

I think it is kconfig not being really transitive with select
dependencies. So things like !GENERIC_ATOMIC64 have to be in the
parent that uses select too.

You could also possibly use depends to avoid this, IIRC.

> Anyway, this particular build issue can be fixed by adding
> IOMMU_SUPPORT. i.e.

That feels indirect, but maybe it is needed too..

Jason