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

[Xiang W]

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.

Regards,
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
> > > 
> > > 
> >