[PATCH] riscv: RISCV_ISA_SV48 and RISCV_ISA_SV57 should depend on MMU

[PATCH] riscv: RISCV_ISA_SV48 and RISCV_ISA_SV57 should depend on MMU

[Geert Uytterhoeven]

These options are irreleant for nommu systems.

Fixes: 36de74049ec8cb1a ("riscv: introduce RISCV_ISA_SV48 and RISCV_ISA_SV57")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 arch/riscv/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 15f6e67c60410a87..15beeb4690aebcc4 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -605,7 +605,7 @@ config RISCV_ISA_SSQOSID
 
 config RISCV_ISA_SV48
 	bool "Page-Based 48-bit Virtual-Memory System"
-	depends on 64BIT
+	depends on 64BIT && MMU
 	default y
 	help
 	  Add support for the Page-Based 48-bit Virtual-Memory System.
@@ -617,7 +617,7 @@ config RISCV_ISA_SV48
 
 config RISCV_ISA_SV57
 	bool "Page-Based 57-bit Virtual-Memory System"
-	depends on 64BIT
+	depends on 64BIT && MMU
 	default y
 	help
 	  Add support for the Page-Based 57-bit Virtual-Memory System.
-- 
2.43.0

Re: [PATCH] riscv: RISCV_ISA_SV48 and RISCV_ISA_SV57 should depend on MMU

[Jisheng Zhang]

On Wed, Oct 14, 2026 at 12:20:39PM +0200, Geert Uytterhoeven wrote:
> These options are irreleant for nommu systems.
> 
> Fixes: 36de74049ec8cb1a ("riscv: introduce RISCV_ISA_SV48 and RISCV_ISA_SV57")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
>  arch/riscv/Kconfig | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 15f6e67c60410a87..15beeb4690aebcc4 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -605,7 +605,7 @@ config RISCV_ISA_SSQOSID
>  
>  config RISCV_ISA_SV48
>  	bool "Page-Based 48-bit Virtual-Memory System"
> -	depends on 64BIT
> +	depends on 64BIT && MMU
>  	default y
>  	help
>  	  Add support for the Page-Based 48-bit Virtual-Memory System.
> @@ -617,7 +617,7 @@ config RISCV_ISA_SV48
>  
>  config RISCV_ISA_SV57
>  	bool "Page-Based 57-bit Virtual-Memory System"
> -	depends on 64BIT
> +	depends on 64BIT && MMU

hmm, I think we also need to make RISCV_ISA_SV57 depend on
RISCV_ISA_SV48. Otherwise, there's a case: RISCV_ISA_SV57 &&
!RISCV_ISA_SV48. Human won't make this wrong combination, but
the random config can.

with that change,
Reviewed-by: Jisheng Zhang <jszhang@kernel.org>

>  	default y
>  	help
>  	  Add support for the Page-Based 57-bit Virtual-Memory System.
> -- 
> 2.43.0
> 

Re: [PATCH] riscv: RISCV_ISA_SV48 and RISCV_ISA_SV57 should depend on MMU

[Geert Uytterhoeven]

Hi Jisheng,

On Thu, 15 Oct 2026 at 01:48, Jisheng Zhang <jszhang@kernel.org> wrote:
> On Wed, Oct 14, 2026 at 12:20:39PM +0200, Geert Uytterhoeven wrote:
> > These options are irreleant for nommu systems.
> >
> > Fixes: 36de74049ec8cb1a ("riscv: introduce RISCV_ISA_SV48 and RISCV_ISA_SV57")
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -605,7 +605,7 @@ config RISCV_ISA_SSQOSID
> >
> >  config RISCV_ISA_SV48
> >       bool "Page-Based 48-bit Virtual-Memory System"
> > -     depends on 64BIT
> > +     depends on 64BIT && MMU
> >       default y
> >       help
> >         Add support for the Page-Based 48-bit Virtual-Memory System.
> > @@ -617,7 +617,7 @@ config RISCV_ISA_SV48
> >
> >  config RISCV_ISA_SV57
> >       bool "Page-Based 57-bit Virtual-Memory System"
> > -     depends on 64BIT
> > +     depends on 64BIT && MMU
>
> hmm, I think we also need to make RISCV_ISA_SV57 depend on
> RISCV_ISA_SV48. Otherwise, there's a case: RISCV_ISA_SV57 &&
> !RISCV_ISA_SV48. Human won't make this wrong combination, but
> the random config can.

Is that really an issue?
If I build a kernel for an SV57-system, do I really need to enable
support for SV48, too? It builds fine without...

> with that change,
> Reviewed-by: Jisheng Zhang <jszhang@kernel.org>

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds