Previously, ATOMIC_OPERATIONS_C was selected for RISC-V whenever the
'A' (atomic) ISA extension (RISCV_ISA_EXT_A) was absent. This caused
a conflict on platforms that lack the 'A' extension but still provide
their own arch-level atomic implementation via ATOMIC_OPERATIONS_ARCH
(e.g. future RISC-V SoCs with custom atomic support).
Add !ATOMIC_OPERATIONS_ARCH to the select condition so that the
generic C fallback (interrupt-locking) is only chosen when neither
the ISA extension nor an arch-specific implementation is available.
This condition creates a Kconfig dependency cycle:
RISCV selects ATOMIC_OPERATIONS_C if !ATOMIC_OPERATIONS_ARCH
=> ATOMIC_OPERATIONS_C depends on !ATOMIC_OPERATIONS_ARCH
=> ATOMIC_OPERATIONS_ARCH depends on SMP (fvp_base_revc_2xaem board)
=> SMP depends on !ATOMIC_OPERATIONS_C
Break the cycle by removing 'depends on !ATOMIC_OPERATIONS_C' from
SMP in kernel/smp/Kconfig. This is safe because ATOMIC_OPERATIONS_C
is now only selected when ATOMIC_OPERATIONS_ARCH is absent, so the
two symbols are mutually exclusive by construction. The existing
BUILD_ASSERT(!IS_ENABLED(CONFIG_SMP)) in lib/os/atomic_c.c provides
a compile-time backstop against any misconfiguration.
Suggested-by: Nicolas Pitre <npitre@baylibre.com>
Signed-off-by: Lingutla Chandrasekhar <lingutla@qti.qualcomm.com>
a5fbcbb12c