[v1] riscv: Implement ARCH_HAS_CC_CAN_LINK

[PATCH] riscv: Implement ARCH_HAS_CC_CAN_LINK

Posted by Thomas Weißschuh 1 month, 2 weeks ago

The generic CC_CAN_LINK detection relies on -m32/-m64 compiler flags.
These are not supported by riscv compilers.

Use architecture-specific logic using -mabi instead.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/riscv/Kconfig | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 6b39f37f769a..b4c1f922eed5 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -25,6 +25,7 @@ config RISCV
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
 	select ARCH_HAS_BINFMT_FLAT
+	select ARCH_HAS_CC_CAN_LINK
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DEBUG_VM_PGTABLE
@@ -1351,6 +1352,16 @@ config PORTABLE
 config ARCH_PROC_KCORE_TEXT
 	def_bool y
 
+config ARCH_CC_CAN_LINK
+	bool
+	default $(cc_can_link_user,-mabi=lp64d) if 64BIT
+	default $(cc_can_link_user,-mabi=ilp32d)
+
+config ARCH_USERFLAGS
+	string
+	default "-mabi=lp64d" if 64BIT
+	default "-mabi=ilp32d"
+
 menu "Power management options"
 
 source "kernel/power/Kconfig"

---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251222-cc-can-link-riscv-dc0304d27cf4

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@linutronix.de>

Re: [PATCH] riscv: Implement ARCH_HAS_CC_CAN_LINK

Posted by Paul Walmsley 3 weeks, 2 days ago

Hi,

On Mon, 22 Dec 2025, Thomas Weißschuh wrote:

> The generic CC_CAN_LINK detection relies on -m32/-m64 compiler flags.
> These are not supported by riscv compilers.
> 
> Use architecture-specific logic using -mabi instead.
> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---
>  arch/riscv/Kconfig | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 6b39f37f769a..b4c1f922eed5 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -25,6 +25,7 @@ config RISCV
>  	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
>  	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
>  	select ARCH_HAS_BINFMT_FLAT
> +	select ARCH_HAS_CC_CAN_LINK
>  	select ARCH_HAS_CURRENT_STACK_POINTER
>  	select ARCH_HAS_DEBUG_VIRTUAL if MMU
>  	select ARCH_HAS_DEBUG_VM_PGTABLE
> @@ -1351,6 +1352,16 @@ config PORTABLE
>  config ARCH_PROC_KCORE_TEXT
>  	def_bool y
>  
> +config ARCH_CC_CAN_LINK
> +	bool
> +	default $(cc_can_link_user,-mabi=lp64d) if 64BIT
> +	default $(cc_can_link_user,-mabi=ilp32d)
> +
> +config ARCH_USERFLAGS
> +	string
> +	default "-mabi=lp64d" if 64BIT
> +	default "-mabi=ilp32d"
> +

Any reason why this patch shouldn't use the non-d ABI variants, as the 
rest of arch/riscv/Kconfig does?  I suspect this may not work for 
!CONFIG_FPU builds.


- Paul

Re: [PATCH] riscv: Implement ARCH_HAS_CC_CAN_LINK

Posted by Thomas Weißschuh 3 weeks, 2 days ago

Hi Paul,

On Thu, Jan 15, 2026 at 09:50:20PM -0700, Paul Walmsley wrote:
> On Mon, 22 Dec 2025, Thomas Weißschuh wrote:
> 
> > The generic CC_CAN_LINK detection relies on -m32/-m64 compiler flags.
> > These are not supported by riscv compilers.
> > 
> > Use architecture-specific logic using -mabi instead.
> > 
> > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> > ---
> >  arch/riscv/Kconfig | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 6b39f37f769a..b4c1f922eed5 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -25,6 +25,7 @@ config RISCV
> >  	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
> >  	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
> >  	select ARCH_HAS_BINFMT_FLAT
> > +	select ARCH_HAS_CC_CAN_LINK
> >  	select ARCH_HAS_CURRENT_STACK_POINTER
> >  	select ARCH_HAS_DEBUG_VIRTUAL if MMU
> >  	select ARCH_HAS_DEBUG_VM_PGTABLE
> > @@ -1351,6 +1352,16 @@ config PORTABLE
> >  config ARCH_PROC_KCORE_TEXT
> >  	def_bool y
> >  
> > +config ARCH_CC_CAN_LINK
> > +	bool
> > +	default $(cc_can_link_user,-mabi=lp64d) if 64BIT
> > +	default $(cc_can_link_user,-mabi=ilp32d)
> > +
> > +config ARCH_USERFLAGS
> > +	string
> > +	default "-mabi=lp64d" if 64BIT
> > +	default "-mabi=ilp32d"
> > +
> 
> Any reason why this patch shouldn't use the non-d ABI variants, as the 
> rest of arch/riscv/Kconfig does?  I suspect this may not work for 
> !CONFIG_FPU builds.

Toolchains tend to only provide a libc for the 'd' ABI variants.
At least the ones I checked in Debian, Arch Linux and
https://toolchains.bootlin.com/. So I'd like to prefer those to increase
the chance of CONFIG_CC_CAN_LINK=y.

I'll add dedicated clauses for FPU=n in the next revision.

It would also be possible to have non-d as a fallback for FPU=y, but it
is slightly more complex to represent and will probably never be used.


Thomas