Binutils-2.38 and GCC-12.1.0 bump[0] default ISA spec to newer version 20191213 which moves some instructions from the I extension to the Zicsr and Zifencei extensions. So if one of the binutils and GCC exceeds that version, we should turn on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI to cope with the new changes.
The case of clang is special[1][2], where older clang versions (<17) need to be rolled back to old ISA spec to fix it. And the less common case, since older GCC versions (<11.1.0) did not support zicsr and zifencei extension for -march, also requires a fallback to cope with it.
For more information, please refer to: commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38") commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils") Link: https://gcc.gnu.org/git/?p=gcc.git%3Ba=commit%3Bh=98416dbb0a62579d4a7a4a76ba... [0] Link: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org [1] Link: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org [2] Link: https://lore.kernel.org/all/20230725170405.251011-1-xingmingzheng@iscas.ac.c... Signed-off-by: Mingzheng Xing xingmingzheng@iscas.ac.cn ---
v2: - Update the Kconfig help text and commit message. - Add considerations for low version gcc case.
Sorry for the formatting error on my mailing list reply.
arch/riscv/Kconfig | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 4c07b9189c86..08afd47de157 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -570,24 +570,27 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI def_bool y # https://sourceware.org/git/?p=binutils-gdb.git%3Ba=commit%3Bh=aed44286efa8ae... - depends on AS_IS_GNU && AS_VERSION >= 23800 + # https://gcc.gnu.org/git/?p=gcc.git%3Ba=commit%3Bh=98416dbb0a62579d4a7a4a76ba... + depends on GCC_VERSION >= 120100 || (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. + Binutils-2.38 and GCC-12.1.0 bump default ISA spec to newer 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/22e199e6afb1263c943c0c0d4498694e... - depends on CC_IS_CLANG && CLANG_VERSION < 170000 + # https://gcc.gnu.org/git/?p=gcc.git%3Ba=commit%3Bh=b03be74bad08c382da47e04800... + depends on (CC_IS_CLANG && CLANG_VERSION < 170000) || \ + (CC_IS_GCC && GCC_VERSION < 110100) 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 + Certain versions of clang (or GCC) 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. + of clang (or GCC) to be passed to GAS, which has the same result as + passing zicsr and zifencei to -march.
config FPU bool "FPU support"