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-rw-r--r--arch/riscv/Kconfig22
-rw-r--r--arch/riscv/Makefile10
2 files changed, 28 insertions, 4 deletions
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index c5e42cc37604..5b182d1c196c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -464,6 +464,28 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zihintpause)
depends on LLD_VERSION >= 150000 || LD_VERSION >= 23600
+config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
+ def_bool y
+ # https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
+ depends on AS_IS_GNU && AS_VERSION >= 23800
+ help
+ Newer binutils versions default to ISA spec version 20191213 which
+ moves some instructions from the I extension to the Zicsr and Zifencei
+ extensions.
+
+config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
+ def_bool y
+ depends on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
+ # https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
+ depends on CC_IS_CLANG && CLANG_VERSION < 170000
+ help
+ Certain versions of clang do not support zicsr and zifencei via -march
+ but newer versions of binutils require it for the reasons noted in the
+ help text of CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. This
+ option causes an older ISA spec compatible with these older versions
+ of clang to be passed to GAS, which has the same result as passing zicsr
+ and zifencei to -march.
+
config FPU
bool "FPU support"
default y
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 4de83b9b1772..b05e833a022d 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -57,10 +57,12 @@ riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima
riscv-march-$(CONFIG_FPU) := $(riscv-march-y)fd
riscv-march-$(CONFIG_RISCV_ISA_C) := $(riscv-march-y)c
-# Newer binutils versions default to ISA spec version 20191213 which moves some
-# instructions from the I extension to the Zicsr and Zifencei extensions.
-toolchain-need-zicsr-zifencei := $(call cc-option-yn, -march=$(riscv-march-y)_zicsr_zifencei)
-riscv-march-$(toolchain-need-zicsr-zifencei) := $(riscv-march-y)_zicsr_zifencei
+ifdef CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC
+KBUILD_CFLAGS += -Wa,-misa-spec=2.2
+KBUILD_AFLAGS += -Wa,-misa-spec=2.2
+else
+riscv-march-$(CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI) := $(riscv-march-y)_zicsr_zifencei
+endif
# Check if the toolchain supports Zihintpause extension
riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE) := $(riscv-march-y)_zihintpause