Re: [PATCH v15 03/11] riscv/Kconfig: make direct map manipulation options depend on MMU

[Palmer Dabbelt]

On Sat, 23 Jan 2021 03:00:41 PST (-0800), rppt@xxxxxxxxxx wrote:
> On Fri, Jan 22, 2021 at 08:12:30PM -0800, Palmer Dabbelt wrote:
> > On Wed, 20 Jan 2021 10:06:04 PST (-0800), rppt@xxxxxxxxxx wrote:
> > > From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> > >
> > > ARCH_HAS_SET_DIRECT_MAP and ARCH_HAS_SET_MEMORY configuration options have
> > > no meaning when CONFIG_MMU is disabled and there is no point to enable them
> > > for the nommu case.
> > >
> > > Add an explicit dependency on MMU for these options.
> > >
> > > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > ---
> > >  arch/riscv/Kconfig | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > index d82303dcc6b6..d35ce19ab1fa 100644
> > > --- a/arch/riscv/Kconfig
> > > +++ b/arch/riscv/Kconfig
> > > @@ -25,8 +25,8 @@ config RISCV
> > >  	select ARCH_HAS_KCOV
> > >  	select ARCH_HAS_MMIOWB
> > >  	select ARCH_HAS_PTE_SPECIAL
> > > -	select ARCH_HAS_SET_DIRECT_MAP
> > > -	select ARCH_HAS_SET_MEMORY
> > > +	select ARCH_HAS_SET_DIRECT_MAP if MMU
> > > +	select ARCH_HAS_SET_MEMORY if MMU
> > >  	select ARCH_HAS_STRICT_KERNEL_RWX if MMU
> > >  	select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
> > >  	select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
> >
> > Reviewed-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
> > Acked-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
> >
> > LMK if you want this to go in via the RISC-V tree, otherwise I'm going to
> > assume it's going in along with the rest of these.  FWIW I see these in other
> > architectures without the MMU guard.
>
> Except arm, they all always have MMU=y and arm selects only
> ARCH_HAS_SET_MEMORY and has empty stubs for those when MMU=n.

OK, maybe I just checked ARM, then.  I was just making sure.

> Indeed I might have been over zealous adding ARCH_HAS_SET_MEMORY dependency
> on MMU, as riscv also has these stubs, but I thought that making this
> explicit is a nice thing.

It seems reasonable to me.

Thanks!