Hi Conor,
On Thu, Feb 23, 2023 at 10:05:46PM +0000, Conor Dooley wrote:
From: Conor Dooley conor.dooley@microchip.com
Quoting the llvm docs:
Between versions 2.0 and 2.1 of the base I specification, a backwards incompatible change was made to remove selected instructions and CSRs from the base ISA. These instructions were grouped into a set of new extensions, but were no longer required by the base ISA. (snip) LLVM currently implements version 2.0 of the base specification. Thus, instructions from these extensions are accepted as part of the base ISA.
There is therefore no need (at present!) to carry out a $cc-option check, and instead just gate presence of zicsr and zifencei in march on the version of binutils that commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38") highlights as the introduction of the requirement.
In fact, the status quo creates some issues with mixed llvm/binutils builds, specifically building with llvm-17 and ld from binutils-2.35. Odd combo you may think, but this is what tuxsuite's debian stable uses while testing 5.10 stable kernels as doesn't support LLD.
CC: stable@vger.kernel.org # needs RISC-V: move zicsr/zifencei spec version check to Kconfi
I think it would be better to drop this comment and just mark patch 1 for stable directly. However, if it remains, 'Kconfi' -> 'Kconfig' :)
Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Link: https://lore.kernel.org/all/CA+G9fYt9T=ELCLaB9byxaLW2Qf4pZcDO=huCA0D8ug2V2+i... Suggested-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Conor Dooley conor.dooley@microchip.com
Reviewed-by: Nathan Chancellor nathan@kernel.org
Thanks for helping getting down to the bottom of this!
arch/riscv/Kconfig | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 4eb0ef8314b3..c6902f4c5650 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -291,8 +291,7 @@ endchoice config TOOLCHAIN_NEEDS_SPEC_20191213 bool default y
- depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zicsr_zifencei)
- depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zicsr_zifencei)
- 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
-- 2.39.1