On Fri, Mar 05, 2021 at 09:46:49AM +0100, Cornelia Huck wrote:
> On Thu, 4 Mar 2021 21:30:03 -0400
> Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
>
> > VFIO_IOMMU_TYPE1 does not compile with !MMU:
> >
> > ../drivers/vfio/vfio_iommu_type1.c: In function 'follow_fault_pfn':
> > ../drivers/vfio/vfio_iommu_type1.c:536:22: error: implicit declaration of function 'pte_write'; did you mean 'vfs_write'? [-Werror=implicit-function-declaration]
> >
> > So require it.
> >
> > Suggested-by: Cornelia Huck <cohuck@xxxxxxxxxx>
> > Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > drivers/vfio/Kconfig | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
> > index 90c0525b1e0cf4..67d0bf4efa1606 100644
> > +++ b/drivers/vfio/Kconfig
> > @@ -22,7 +22,7 @@ config VFIO_VIRQFD
> > menuconfig VFIO
> > tristate "VFIO Non-Privileged userspace driver framework"
> > select IOMMU_API
> > - select VFIO_IOMMU_TYPE1 if (X86 || S390 || ARM || ARM64)
> > + select VFIO_IOMMU_TYPE1 if MMU && (X86 || S390 || ARM || ARM64)
> > help
> > VFIO provides a framework for secure userspace device drivers.
> > See Documentation/driver-api/vfio.rst for more details.
>
> Actually, I'm wondering how much sense vfio makes on !MMU at all? (And
> maybe just merge this with your patch that switches IOMMU_API from a
> depend to a select, because that is the change that makes the MMU
> dependency required?)
Why does changing depend to select affect MMU vs !MMU? Am I missing
something?
It looks like IOMMU_API can be turned with ARM !MMU here, for
instance:
config MSM_IOMMU
bool "MSM IOMMU Support"
depends on ARM
depends on ARCH_MSM8X60 || ARCH_MSM8960 || COMPILE_TEST
select IOMMU_API
Generally with !MMU I try to ignore it as much as possible unless
things don't compile, as I have no idea what people use it for :)
Jason
