Re: [PATCH] iommu/io-pgtable: Make IOMMU_IO_PGTABLE_DART invisible

[Robin Murphy]

On 2022-09-27 15:48, Geert Uytterhoeven wrote:
> Hi Robin,
>
> On Tue, Sep 27, 2022 at 4:15 PM Robin Murphy <robin.murphy@xxxxxxx> wrote:
> > On 2022-09-27 14:36, Geert Uytterhoeven wrote:
> > > There is no point in asking the user about both "Apple DART Formats" and
> > > "Apple DART IOMMU Support", as the former is useless without the latter,
> > > and the latter auto-selects the former.
> > >
> > > Fixes: 745ef1092bcfcf3b ("iommu/io-pgtable: Move Apple DART support to its own file")
> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > > ---
> > > Should IOMMU_IO_PGTABLE_LPAE and IOMMU_IO_PGTABLE_ARMV7S be made
> > > invisible, too?
> > > Are there users that do not select them?
> >
> > The aim was for formats to be independently selectable for COMPILE_TEST
> > coverage. The Arm formats are manually selectable for the sake of their
> > runtime self-tests, which are self-contained, but since DART format
> > doesn't do anything by itself I'd agree there's no need to prompt when
> > !COMPILE_TEST here.
>
> IOMMU_IO_PGTABLE_LPAE and IOMMU_IO_PGTABLE_ARMV7S are
> selected by other symbols that can be enabled when compile-testing, so
> the tests can still be enabled in those cases, too

Sure, but when you want to compile-test a thing, what would you rather 
do: enable the thing, or go hunting to find some other thing that 
happens to select the thing you actually want, then potentially have to 
figure out *that* thing's dependencies, and so on?

Coverage isn't solely about whether it's technically possible to ever 
reach somewhere at all, it's just as much about how easily and/or often 
you can get there in practice. I don't see who benefits from making 
COMPILE_TEST harder to use :/

Thanks,
Robin.