Re: [Xen-devel] [PATCH v3 07/10] arm: make it possible to disable the SMMU driver

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 23 May 2018, Andrii Anisov wrote:
> Hello Stefano,
> 
> 
> On 23.05.18 03:25, Stefano Stabellini wrote:
> > Introduce a Kconfig option for the ARM SMMUv1 and SMMUv2 driver.
> > 
> > Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > CC: jbeulich@xxxxxxxx
> > 
> > ---
> > Changes in v3:
> > - rename SMMUv2 to ARM_SMMU
> > - improve help message
> > - use if ARM
> > 
> > Changes in v2:
> > - rename HAS_SMMUv2 to SMMUv2
> > - move SMMUv2 to xen/drivers/passthrough/Kconfig
> > ---
> >   xen/drivers/passthrough/Kconfig      | 12 ++++++++++++
> >   xen/drivers/passthrough/arm/Makefile |  2 +-
> >   2 files changed, 13 insertions(+), 1 deletion(-)
> > 
> > diff --git a/xen/drivers/passthrough/Kconfig
> > b/xen/drivers/passthrough/Kconfig
> > index 8d90b67..a3c0649 100644
> > --- a/xen/drivers/passthrough/Kconfig
> > +++ b/xen/drivers/passthrough/Kconfig
> > @@ -1,3 +1,15 @@
> >     config HAS_PASSTHROUGH
> >     bool
> > +
> > +if ARM
> > +config ARM_SMMU
> > +   bool "ARM SMMUv1 and v2 driver"
> > +   default y
> Did you mean here "default n"? So in a platform selecting configs patch you
> silently skipping it for QEMU and RCAR3, but enabling for MPSOC?

I meant "default y" because I am only trying to introduce the options
in this patch series, I am not trying to change the defaults (yet).

In any case, even with "default y" it works as intended if you start
from tiny.config.

1) cp arch/arm/configs/tiny.conf .config
2) make olddefconfig
3) make menuconfig -> select RCAR3

the results is that ARM_SMMU will be disabled because it is already
disabled in tiny.config and CONFIG_RCAR3 won't enable it.


> > +   ---help---
> > +     Support for implementations of the ARM System MMU architecture
> > +     versions 1 and 2.
> > +
> > +     Say Y here if your SoC includes an IOMMU device implementing the
> > +     ARM SMMU architecture.
> > +endif
> > diff --git a/xen/drivers/passthrough/arm/Makefile
> > b/xen/drivers/passthrough/arm/Makefile
> > index f4cd26e..0156431 100644
> > --- a/xen/drivers/passthrough/arm/Makefile
> > +++ b/xen/drivers/passthrough/arm/Makefile
> > @@ -1,2 +1,2 @@
> >   obj-y += iommu.o
> > -obj-y += smmu.o
> > +obj-$(ARM_SMMU) += smmu.o

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