On Mon, Feb 27, 2023 at 08:40:46AM -0500, Darius Rad wrote: > On Mon, Feb 27, 2023 at 10:18:34AM +0000, Conor Dooley wrote: > > On Fri, Feb 24, 2023 at 05:01:18PM +0000, Andy Chiu wrote: > > > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > > > > > This patch adds a config which enables vector feature from the kernel > > > space. > > > > > > Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > > Co-developed-by: Greentime Hu <greentime.hu@xxxxxxxxxx> > > > Signed-off-by: Greentime Hu <greentime.hu@xxxxxxxxxx> > > > Suggested-by: Vineet Gupta <vineetg@xxxxxxxxxxxx> > > > Suggested-by: Atish Patra <atishp@xxxxxxxxxxxxxx> > > > Signed-off-by: Andy Chiu <andy.chiu@xxxxxxxxxx> > > > > At this point, you've basically re-written this patch and should be > > listed as a co-author at the very least! > > > > > --- > > > arch/riscv/Kconfig | 18 ++++++++++++++++++ > > > arch/riscv/Makefile | 3 ++- > > > 2 files changed, 20 insertions(+), 1 deletion(-) > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > index 81eb031887d2..19deeb3bb36b 100644 > > > --- a/arch/riscv/Kconfig > > > +++ b/arch/riscv/Kconfig > > > @@ -418,6 +418,24 @@ config RISCV_ISA_SVPBMT > > > > > > If you don't know what to do here, say Y. > > > > > > +config TOOLCHAIN_HAS_V > > > + bool > > > + default y > > > + depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64iv) > > > + depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32iv) > > > + depends on LLD_VERSION >= 140000 || LD_VERSION >= 23800 > > > + > > > +config RISCV_ISA_V > > > + bool "VECTOR extension support" > > > + depends on TOOLCHAIN_HAS_V > > > + select DYNAMIC_SIGFRAME > > > > So, nothing here makes V depend on CONFIG_FPU... > > > > > + default y > > > + help > > > + Say N here if you want to disable all vector related procedure > > > + in the kernel. > > > + > > > + If you don't know what to do here, say Y. > > > + > > > config TOOLCHAIN_HAS_ZBB > > > bool > > > default y > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > > > index 76989561566b..375a048b11cb 100644 > > > --- a/arch/riscv/Makefile > > > +++ b/arch/riscv/Makefile > > > @@ -56,6 +56,7 @@ riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima > > > riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima > > > riscv-march-$(CONFIG_FPU) := $(riscv-march-y)fd > > > > ...but march only contains fd if CONFIG_FPU is enabled... > > > > > riscv-march-$(CONFIG_RISCV_ISA_C) := $(riscv-march-y)c > > > +riscv-march-$(CONFIG_RISCV_ISA_V) := $(riscv-march-y)v > > > > > > # Newer binutils versions default to ISA spec version 20191213 which moves some > > > # instructions from the I extension to the Zicsr and Zifencei extensions. > > > @@ -65,7 +66,7 @@ riscv-march-$(toolchain-need-zicsr-zifencei) := $(riscv-march-y)_zicsr_zifencei > > > # Check if the toolchain supports Zihintpause extension > > > riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE) := $(riscv-march-y)_zihintpause > > > > > > -KBUILD_CFLAGS += -march=$(subst fd,,$(riscv-march-y)) > > > +KBUILD_CFLAGS += -march=$(subst fdv,,$(riscv-march-y)) > > > > ...so I think this will not work if !CONFIG_FPU && RISCV_ISA_V. > > IIRC, vector uses some floating point opcodes, but does it (or Linux's > > implementation) actually depend on having floating point support in the > > kernel? > > Yes. > > "The V extension requires the scalar processor implements the F and D > extensions", RISC-V "V" Vector Extension, Section 18.3. V: Vector Extension > for Application Processors. Thanks, I should probably just have gone and read the spec! > > If not, this cannot be done in a oneliner. Otherwise, CONFIG_RISCV_ISA_V > > should explicitly depend on CONFIG_FPU. Since it does depend on F & D, the Kconfig symbol should explicitly depend on CONFIG_FPU. The oneliner like that still doesn't work, as V is added to march after C, leading (for clang-15 allmodconfig) to: -march=rv64imafdcv_zihintpause Doing it as a oneline also breaks the case where CONFIG_FPU && !RISCV_ISA_VECTOR, which ends up with: -march=rv64imafdc_zihintpause. Cheers, Conor.
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