Re: [PATCH v2 3/7] iommu/arm-smmu: Add dependency on io-pgtable format modules

[isaacm]

On 2020-12-23 05:05, Robin Murphy wrote:
> On 2020-12-22 19:49, isaacm@xxxxxxxxxxxxxx wrote:
> > On 2020-12-22 11:27, Robin Murphy wrote:
> > > On 2020-12-22 00:44, Isaac J. Manjarres wrote:
> > > > The SMMU driver depends on the availability of the ARM LPAE and
> > > > ARM V7S io-pgtable format code to work properly. In preparation
> > >
> > > Nit: we don't really depend on v7s - we *can* use it if it's
> > > available, address constraints are suitable, and the SMMU
> > > implementation actually supports it (many don't), but we can still
> > > quite happily not use it even so. LPAE is mandatory in the
> > > architecture so that's our only hard requirement, embodied in the
> > > kconfig select.
> > >
> > > This does mean there may technically still be a corner case involving
> > > ARM_SMMU=y and IO_PGTABLE_ARM_V7S=m, but at worst it's now a runtime
> > > failure rather than a build error, so unless and until anyone
> > > demonstrates that it actually matters I don't feel particularly
> > > inclined to give it much thought.
> > >
> > > Robin.
> > Okay, I'll fix up the commit message, as well as the code, so that it
> > only depends on io-pgtable-arm.
>
> Well, IIUC it would make sense to keep the softdep for when the v7s
> module *is* present; I just wanted to clarify that it's more of a
> nice-to-have rather than a necessity.
>
> Robin.
Understood, I will keep it there and reword the commit msg. I just tried 
it out in an environment
where the io-pgtable-arm-v7s module isn't present, and I didn't see any
warnings or error messages, and the SMMU driver module was loaded 
properly,
so yes, it's good to have it.

Thanks,
Isaac
> > Thanks,
> > Isaac
> > > > for having the io-pgtable formats as modules, add a "pre"
> > > > dependency with MODULE_SOFTDEP() to ensure that the io-pgtable
> > > > format modules are loaded before loading the ARM SMMU driver module.
> > > >
> > > > Signed-off-by: Isaac J. Manjarres <isaacm@xxxxxxxxxxxxxx>
> > > > ---
> > > >   drivers/iommu/arm/arm-smmu/arm-smmu.c | 1 +
> > > >   1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c 
> > > > b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > > index d8c6bfd..a72649f 100644
> > > > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > > @@ -2351,3 +2351,4 @@ MODULE_DESCRIPTION("IOMMU API for ARM 
> > > > architected SMMU implementations");
> > > >   MODULE_AUTHOR("Will Deacon <will@xxxxxxxxxx>");
> > > >   MODULE_ALIAS("platform:arm-smmu");
> > > >   MODULE_LICENSE("GPL v2");
> > > > +MODULE_SOFTDEP("pre: io-pgtable-arm io-pgtable-arm-v7s");
> > >
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