linux-kernel - [PATCH v2] riscv: Implement ARCH_HAS_CC_CAN

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Message-Id: <20260116-cc-can-link-riscv-v2-1-eaf362d74c90@linutronix.de>
Date: Fri, 16 Jan 2026 07:19:24 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, 
 Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH v2] riscv: Implement ARCH_HAS_CC_CAN_LINK

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.

Prefer the 'd' ABI variant when possible as todays toolchains are most
likely to provide a libc for that one.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
Changes in v2:
- Also handle !FPU case.
- Extend commit message.
- Link to v1: https://lore.kernel.org/r/20251222-cc-can-link-riscv-v1-1-633e39e4a60d@linutronix.de
---
 arch/riscv/Kconfig | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 6b39f37f769a..1c636117b7e4 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 +1352,20 @@ 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 && FPU
+	default $(cc_can_link_user,-mabi=lp64) if 64BIT
+	default $(cc_can_link_user,-mabi=ilp32d) if FPU
+	default $(cc_can_link_user,-mabi=ilp32)
+
+config ARCH_USERFLAGS
+	string
+	default "-mabi=lp64d" if 64BIT && FPU
+	default "-mabi=lp64" if 64BIT
+	default "-mabi=ilp32d" if FPU
+	default "-mabi=ilp32"
+
 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@...utronix.de>