[PATCH 2/2] Makefile: Don't enable V-extension using -march option

[Xiang W]

在 2024-12-11三的 02:58 +0000，Jessica Clarke写道：
> On 11 Dec 2024, at 02:41, Xiang W <wxjstz at 126.com> wrote:
> > 
> > 在 2024-12-10二的 10:46 +0530，Anup Patel写道：
> > > On Tue, Dec 10, 2024 at 10:35 AM Xiang W <wxjstz at 126.com> wrote:
> > > > 
> > > > 在 2024-12-10二的 09:46 +0530，Anup Patel写道：
> > > > > Enabling V-extension using -march option causes OpenSBI boot-time
> > > > > hang with LLVM compiler.
> > > > > 
> > > > > As a work-around, don't enable V-extension using -march option and
> > > > > instead use a custom OpenSBI specific define inform availability of
> > > > > V-extension to lib/sbi/sbi_trap_v_ldst.c.
> > > > > 
> > > > > Fixes: c2acc5e5b0d8 ("lib: sbi_misaligned_ldst: Add handling of vector load/store")
> > > > > Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> > > > > ---
> > > > >  Makefile                  | 8 ++++----
> > > > >  lib/sbi/sbi_trap_v_ldst.c | 5 +++--
> > > > >  2 files changed, 7 insertions(+), 6 deletions(-)
> > > > > 
> > > > > diff --git a/Makefile b/Makefile
> > > > > index 5ac95a0f..7e0a1399 100644
> > > > > --- a/Makefile
> > > > > +++ b/Makefile
> > > > > @@ -190,7 +190,7 @@ CC_SUPPORT_STRICT_ALIGN := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) -nostdlib
> > > > >  CC_SUPPORT_ZICSR_ZIFENCEI := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) -nostdlib -march=rv$(OPENSBI_CC_XLEN)imafd_zicsr_zifencei -x
> > > > > c
> > > > > /dev/null -o /dev/null 2>&1 | grep -e "zicsr" -e "zifencei" > /dev/null && echo n || echo y)
> > > > > 
> > > > >  # Check whether the assembler and the compiler support the Vector extension
> > > > > -CC_SUPPORT_VECT := $(shell echo | $(CC) -dM -E -march=rv$(OPENSBI_CC_XLEN)gv - | grep -q riscv.*vector && echo y || echo n)
> > > > > +CC_SUPPORT_VECT := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) -nostdlib -march=rv$(OPENSBI_CC_XLEN)gv -dM -E -x c /dev/null 2>&1 |
> > > > > grep
> > > > > -q
> > > > > riscv.*vector && echo y || echo n)
> > > > > 
> > > > >  ifneq ($(OPENSBI_LD_PIE),y)
> > > > >  $(error Your linker does not support creating PIEs, opensbi requires this.)
> > > > > @@ -298,9 +298,6 @@ endif
> > > > >  ifndef PLATFORM_RISCV_ISA
> > > > >    ifneq ($(PLATFORM_RISCV_TOOLCHAIN_DEFAULT), 1)
> > > > >      PLATFORM_RISCV_ISA := rv$(PLATFORM_RISCV_XLEN)imafdc
> > > > > -    ifeq ($(CC_SUPPORT_VECT), y)
> > > > > -      PLATFORM_RISCV_ISA := $(PLATFORM_RISCV_ISA)v
> > > > > -    endif
> > > > >      ifeq ($(CC_SUPPORT_ZICSR_ZIFENCEI), y)
> > > > >        PLATFORM_RISCV_ISA := $(PLATFORM_RISCV_ISA)_zicsr_zifencei
> > > > >      endif
> > > > > @@ -363,6 +360,9 @@ GENFLAGS  +=      $(firmware-genflags-y)
> > > > >  CFLAGS               =       -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -ffunction-sections
> > > > > -
> > > > > fdata-
> > > > > sections
> > > > >  CFLAGS               +=      -fno-omit-frame-pointer -fno-optimize-sibling-calls
> > > > >  # Optionally supported flags
> > > > > +ifeq ($(CC_SUPPORT_VECT),y)
> > > > > +CFLAGS               +=      -DOPENSBI_CC_SUPPORT_VECT -fno-tree-vectorize
> > > > > +endif
> > > > Suggest adding an else branch to add $(warning) to indicate that the toolchain needs to be updated.
> > > 
> > > I don't think such a warning is needed. The Linux kernel also does not
> > > warn about it.
> > If the warning is not added to the makefile, it can only be used to generateOPENSBI_CC_SUPPORT_VECT macros in place of the __riscv_vector
> > macros, which
> > only adds to the complexity. It is recommended to remove the detection of the
> > v extension from the makefile and revert to using __riscv_vector in 
> > sbi_trap_v_ldst.c.
> 
> Without V enabled you won’t get __riscv_vector defined. Enabling V
> outside of code that’s explicitly expecting to use vectors is wrong, as
> discussed before. Defining __riscv_vector manually would also be wrong,
> and could break compiler headers. The only correct approach is to have
> a different macro defined, with V not in the default -march.
> 
Thank for the reply

Regards,
Xiang W
> Jess
> 
> > Xiang W
> > > 
> > > Regards,
> > > Anup
> > > 
> > > > 
> > > > Regards,
> > > > Xiang W
> > > > >  ifeq ($(CC_SUPPORT_SAVE_RESTORE),y)
> > > > >  CFLAGS               +=      -mno-save-restore
> > > > >  endif
> > > > > diff --git a/lib/sbi/sbi_trap_v_ldst.c b/lib/sbi/sbi_trap_v_ldst.c
> > > > > index 9929215c..75b79baa 100644
> > > > > --- a/lib/sbi/sbi_trap_v_ldst.c
> > > > > +++ b/lib/sbi/sbi_trap_v_ldst.c
> > > > > @@ -17,7 +17,8 @@
> > > > >  #include <sbi/sbi_unpriv.h>
> > > > >  #include <sbi/sbi_trap.h>
> > > > > 
> > > > > -#ifdef __riscv_vector
> > > > > +#ifdef OPENSBI_CC_SUPPORT_VECT
> > > > > +
> > > > >  #define VLEN_MAX 65536
> > > > > 
> > > > >  static inline void set_vreg(ulong vlenb, ulong which,
> > > > > @@ -340,4 +341,4 @@ int sbi_misaligned_v_st_emulator(int wlen, union sbi_ldst_data in_val,
> > > > >  {
> > > > >       return 0;
> > > > >  }
> > > > > -#endif /* __riscv_vector  */
> > > > > +#endif /* OPENSBI_CC_SUPPORT_VECT  */
> > > > > --
> > > > > 2.43.0
> > > > > 
> > > > > 
> > > > 
> > 
> > 
> > 
> > -- 
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>