| Message ID | 20210514205643.383422-1-raj.khem@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | riscv: Use -mno-relax when using lld linker | expand |
Hi Khem, On 5/14/2021 1:56 PM, Khem Raj wrote: > lld does not implement the RISCV relaxation optimizations like GNU ld > therefore disable it when building with LLVM=1, Also pass it to > assembler when using external GNU assembler ( LLVM_IAS != 1 ), this > ensures that relevant assembler option is also enabled along. if these > options are not used then we see following relocations in objects > > 0000000000000000 R_RISCV_ALIGN *ABS*+0x0000000000000002 > > These are then rejected by lld > ld.lld: error: capability.c:(.fixup+0x0): relocation R_RISCV_ALIGN requires unimplemented linker relaxation; recompile with -mno-relax but the .o is already compiled with -mno-relax > > Signed-off-by: Khem Raj <raj.khem@gmail.com> > Cc: Paul Walmsley <paul.walmsley@sifive.com> > Cc: Palmer Dabbelt <palmer@dabbelt.com> > Cc: Albert Ou <aou@eecs.berkeley.edu> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> Thank you for the patch! I can build a ARCH=riscv defconfig kernel with LLVM=1 now. LLVM_IAS=1 still needs work but we have outstanding issues for that: https://github.com/ClangBuiltLinux/linux/issues/1023 https://github.com/ClangBuiltLinux/linux/issues/1143 Reviewed-by: Nathan Chancellor <nathan@kernel.org> One comment below though. > --- > arch/riscv/Makefile | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > index 3eb9590a0775..519f133e0d53 100644 > --- a/arch/riscv/Makefile > +++ b/arch/riscv/Makefile > @@ -38,6 +38,15 @@ else > KBUILD_LDFLAGS += -melf32lriscv > endif > > +ifeq ($(LLVM),1) ifeq ($(CONFIG_LD_IS_LLD),y) is a better choice so that LD=riscv64-linux-gnu-ld LLVM=1 can still work. > + KBUILD_CFLAGS += -mno-relax > + KBUILD_AFLAGS += -mno-relax > +ifneq ($(LLVM_IAS),1) > + KBUILD_CFLAGS += -Wa,-mno-relax > + KBUILD_AFLAGS += -Wa,-mno-relax > +endif > +endif > + > # ISA string setting > riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima > riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima >
On Fri, May 14, 2021 at 1:57 PM Khem Raj <raj.khem@gmail.com> wrote: > > lld does not implement the RISCV relaxation optimizations like GNU ld > therefore disable it when building with LLVM=1, Also pass it to > assembler when using external GNU assembler ( LLVM_IAS != 1 ), this > ensures that relevant assembler option is also enabled along. if these > options are not used then we see following relocations in objects > > 0000000000000000 R_RISCV_ALIGN *ABS*+0x0000000000000002 > > These are then rejected by lld > ld.lld: error: capability.c:(.fixup+0x0): relocation R_RISCV_ALIGN requires unimplemented linker relaxation; recompile with -mno-relax but the .o is already compiled with -mno-relax This means -mno-relax should emit .option norelax in the assembly. I'll try fixing this in Clang 13. > Signed-off-by: Khem Raj <raj.khem@gmail.com> > Cc: Paul Walmsley <paul.walmsley@sifive.com> > Cc: Palmer Dabbelt <palmer@dabbelt.com> > Cc: Albert Ou <aou@eecs.berkeley.edu> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > --- > arch/riscv/Makefile | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > index 3eb9590a0775..519f133e0d53 100644 > --- a/arch/riscv/Makefile > +++ b/arch/riscv/Makefile > @@ -38,6 +38,15 @@ else > KBUILD_LDFLAGS += -melf32lriscv > endif > > +ifeq ($(LLVM),1) > + KBUILD_CFLAGS += -mno-relax > + KBUILD_AFLAGS += -mno-relax > +ifneq ($(LLVM_IAS),1) > + KBUILD_CFLAGS += -Wa,-mno-relax > + KBUILD_AFLAGS += -Wa,-mno-relax > +endif > +endif > + > # ISA string setting > riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima > riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima > -- > 2.31.1 > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210514205643.383422-1-raj.khem%40gmail.com.
On Fri, 14 May 2021 13:56:43 PDT (-0700), Khem Raj wrote: > lld does not implement the RISCV relaxation optimizations like GNU ld > therefore disable it when building with LLVM=1, Also pass it to > assembler when using external GNU assembler ( LLVM_IAS != 1 ), this > ensures that relevant assembler option is also enabled along. if these > options are not used then we see following relocations in objects > > 0000000000000000 R_RISCV_ALIGN *ABS*+0x0000000000000002 > > These are then rejected by lld > ld.lld: error: capability.c:(.fixup+0x0): relocation R_RISCV_ALIGN requires unimplemented linker relaxation; recompile with -mno-relax but the .o is already compiled with -mno-relax > > Signed-off-by: Khem Raj <raj.khem@gmail.com> > Cc: Paul Walmsley <paul.walmsley@sifive.com> > Cc: Palmer Dabbelt <palmer@dabbelt.com> > Cc: Albert Ou <aou@eecs.berkeley.edu> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > --- > arch/riscv/Makefile | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > index 3eb9590a0775..519f133e0d53 100644 > --- a/arch/riscv/Makefile > +++ b/arch/riscv/Makefile > @@ -38,6 +38,15 @@ else > KBUILD_LDFLAGS += -melf32lriscv > endif > > +ifeq ($(LLVM),1) > + KBUILD_CFLAGS += -mno-relax > + KBUILD_AFLAGS += -mno-relax > +ifneq ($(LLVM_IAS),1) > + KBUILD_CFLAGS += -Wa,-mno-relax > + KBUILD_AFLAGS += -Wa,-mno-relax > +endif > +endif > + > # ISA string setting > riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima > riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima Thanks, this is on fixes.
On Sat, 29 May 2021 11:40:39 PDT (-0700), Palmer Dabbelt wrote: > On Fri, 14 May 2021 13:56:43 PDT (-0700), Khem Raj wrote: >> lld does not implement the RISCV relaxation optimizations like GNU ld >> therefore disable it when building with LLVM=1, Also pass it to >> assembler when using external GNU assembler ( LLVM_IAS != 1 ), this >> ensures that relevant assembler option is also enabled along. if these >> options are not used then we see following relocations in objects >> >> 0000000000000000 R_RISCV_ALIGN *ABS*+0x0000000000000002 >> >> These are then rejected by lld >> ld.lld: error: capability.c:(.fixup+0x0): relocation R_RISCV_ALIGN requires unimplemented linker relaxation; recompile with -mno-relax but the .o is already compiled with -mno-relax >> >> Signed-off-by: Khem Raj <raj.khem@gmail.com> >> Cc: Paul Walmsley <paul.walmsley@sifive.com> >> Cc: Palmer Dabbelt <palmer@dabbelt.com> >> Cc: Albert Ou <aou@eecs.berkeley.edu> >> Cc: Nathan Chancellor <nathan@kernel.org> >> Cc: Nick Desaulniers <ndesaulniers@google.com> >> --- >> arch/riscv/Makefile | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile >> index 3eb9590a0775..519f133e0d53 100644 >> --- a/arch/riscv/Makefile >> +++ b/arch/riscv/Makefile >> @@ -38,6 +38,15 @@ else >> KBUILD_LDFLAGS += -melf32lriscv >> endif >> >> +ifeq ($(LLVM),1) >> + KBUILD_CFLAGS += -mno-relax >> + KBUILD_AFLAGS += -mno-relax >> +ifneq ($(LLVM_IAS),1) >> + KBUILD_CFLAGS += -Wa,-mno-relax >> + KBUILD_AFLAGS += -Wa,-mno-relax >> +endif >> +endif >> + >> # ISA string setting >> riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima >> riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima > > Thanks, this is on fixes. Sorry, replied to the v1 but I merged the v2.
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 3eb9590a0775..519f133e0d53 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -38,6 +38,15 @@ else KBUILD_LDFLAGS += -melf32lriscv endif +ifeq ($(LLVM),1) + KBUILD_CFLAGS += -mno-relax + KBUILD_AFLAGS += -mno-relax +ifneq ($(LLVM_IAS),1) + KBUILD_CFLAGS += -Wa,-mno-relax + KBUILD_AFLAGS += -Wa,-mno-relax +endif +endif + # ISA string setting riscv-march-$(CONFIG_ARCH_RV32I) := rv32ima riscv-march-$(CONFIG_ARCH_RV64I) := rv64ima
lld does not implement the RISCV relaxation optimizations like GNU ld therefore disable it when building with LLVM=1, Also pass it to assembler when using external GNU assembler ( LLVM_IAS != 1 ), this ensures that relevant assembler option is also enabled along. if these options are not used then we see following relocations in objects 0000000000000000 R_RISCV_ALIGN *ABS*+0x0000000000000002 These are then rejected by lld ld.lld: error: capability.c:(.fixup+0x0): relocation R_RISCV_ALIGN requires unimplemented linker relaxation; recompile with -mno-relax but the .o is already compiled with -mno-relax Signed-off-by: Khem Raj <raj.khem@gmail.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> --- arch/riscv/Makefile | 9 +++++++++ 1 file changed, 9 insertions(+)