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

[Mike Rapoport]

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.

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.
 
> Thanks!

-- 
Sincerely yours,
Mike.