I'm currently using this to compile with LLVM AR=/usr/lib/llvm-13/bin/llvm-ar \ RANLIB=/usr/lib/llvm-13/bin/llvm-ranlib \ CC=/usr/lib/llvm-13/bin/clang \ CFLAGS="-fuse-ld=/usr/lib/llvm-13/bin/ld.lld --rtlib=compiler-rt --target=armv7a-linux-eabihf -mcpu=cortex-a8" \ LIBCC=-lcompiler_rt \ ./configure \ --prefix=$PREFIX/usr \ --syslibdir=$PREFIX/lib \ --target=armv7a-linux-eabihf \ && make \ && make install This is the output from ./configure checking for C compiler... /usr/lib/llvm-13/bin/clang checking whether C compiler works... yes checking whether compiler accepts -Werror=unknown-warning-option... yes checking whether compiler accepts -Werror=unused-command-line-argument... yes checking whether compiler accepts -Werror=ignored-optimization-argument... yes checking whether linker accepts -Werror=unknown-warning-option... yes checking whether linker accepts -Werror=unused-command-line-argument... yes checking for C compiler family... clang checking for toolchain wrapper to build... clang checking target system type... armv7a-linux-eabihf checking whether compiler accepts -std=c99... yes checking whether compiler accepts -nostdinc... yes checking whether compiler accepts -ffreestanding... yes checking whether compiler accepts -fexcess-precision=standard... no checking whether compiler accepts -frounding-math... yes checking whether compiler needs attribute((may_alias)) suppression... no checking whether compiler accepts -Wa,--noexecstack... yes checking whether compiler accepts -fno-stack-protector... yes checking whether compiler accepts -fno-tree-loop-distribute-patterns... no checking whether we should preprocess assembly to add debugging information... no checking for optimization settings... using defaults checking whether compiler accepts -Os... yes components to be optimized for speed: internal malloc string checking whether compiler accepts -pipe... yes checking whether compiler accepts -fomit-frame-pointer... yes checking whether compiler accepts -fno-unwind-tables... yes checking whether compiler accepts -fno-asynchronous-unwind-tables... yes checking whether compiler accepts -ffunction-sections... yes checking whether compiler accepts -fdata-sections... yes checking whether compiler accepts -w... yes checking whether compiler accepts -Wno-pointer-to-int-cast... yes checking whether compiler accepts -Werror=implicit-function-declaration... yes checking whether compiler accepts -Werror=implicit-int... yes checking whether compiler accepts -Werror=pointer-sign... yes checking whether compiler accepts -Werror=pointer-arith... yes checking whether compiler accepts -Werror=int-conversion... yes checking whether compiler accepts -Werror=incompatible-pointer-types... yes checking whether compiler accepts -Werror=discarded-qualifiers... no checking whether compiler accepts -Werror=discarded-array-qualifiers... no checking whether compiler accepts -Qunused-arguments... yes checking whether compiler accepts -Waddress... yes checking whether compiler accepts -Warray-bounds... yes checking whether compiler accepts -Wchar-subscripts... yes checking whether compiler accepts -Wduplicate-decl-specifier... yes checking whether compiler accepts -Winit-self... yes checking whether compiler accepts -Wreturn-type... yes checking whether compiler accepts -Wsequence-point... yes checking whether compiler accepts -Wstrict-aliasing... yes checking whether compiler accepts -Wunused-function... yes checking whether compiler accepts -Wunused-label... yes checking whether compiler accepts -Wunused-variable... yes checking preprocessor condition __PIC__... false checking whether linker accepts -Wl,--sort-section,alignment... yes checking whether linker accepts -Wl,--sort-common... yes checking whether linker accepts -Wl,--gc-sections... yes checking whether linker accepts -Wl,--hash-style=both... yes checking whether linker accepts -Wl,--no-undefined... yes checking whether linker accepts -Wl,--exclude-libs=ALL... yes checking whether linker accepts -Wl,--dynamic-list=./dynamic.list... yes using compiler runtime libraries: -lcompiler_rt checking preprocessor condition __thumb2__... false checking preprocessor condition __ARMEB__... false checking preprocessor condition __ARM_PCS_VFP... true checking whether clang's vfp asm constraints work... yes configured for arm variant: armhf checking whether compiler's long double definition matches float.h... yes checking preprocessor condition __FAST_MATH__... false creating config.mak... done but now I get this error when compiling ld.lld: error: unable to find library -lcompiler_rt Have I made an error in the way I'm calling ./configure? Just to reiterate, I'm trying to use LLVM to cross compile from x86_64 Linux to armv7a-linux-eabihf. On Tue, Oct 12, 2021 at 5:09 PM Nagakamira wrote: > You can pass --unwindlib=libunwind and rtlib, they are both link options > > On Tue, Oct 12, 2021, 8:55 AM Matt Andrews wrote: > >> > --rtlib=compiler-rt >> >> Is that a compiler option or a linker option? I used it in both places, >> but still get the same error. >> >> On Tue, Oct 12, 2021 at 4:00 PM Nagakamira wrote: >> >>> --rtlib=compiler-rt >>> >>> On Tue, Oct 12, 2021, 7:58 AM Matt Andrews >>> wrote: >>> >>>> > -fuse-ld=lld >>>> >>>> I actually used >>>> >>>> -fuse-ld=ld.lld >>>> >>>> That did the trick, but has unlocked another error >>>> >>>> ld.lld: error: unable to find library -lgcc >>>> ld.lld: error: unable to find library -lgcc_eh >>>> >>>> I thought musl compiles with it's own headers? >>>> >>>> On Tue, Oct 12, 2021 at 3:54 PM Nagakamira >>>> wrote: >>>> >>>>> -fuse-ld=lld >>>>> >>>>> On Tue, Oct 12, 2021, 3:26 AM Jeffrey Walton >>>>> wrote: >>>>> >>>>>> On Mon, Oct 11, 2021 at 7:55 PM Matt Andrews >>>>>> wrote: >>>>>> > >>>>>> > >> How do I specify which linker to use? >>>>>> > > >>>>>> > >LD. Also see >>>>>> https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html >>>>>> . >>>>>> > >>>>>> > Looking at the ./configure for musl (which is not based on autoconf >>>>>> according to the docs), there is no mention of LD. Setting LD for >>>>>> ./configure and/or the call to make still results in the error. >>>>>> > >>>>>> > Who calls the linker? The compiler or make? Shouldn't clang know >>>>>> where it's linker is? How to tell clang which linker to use? >>>>>> >>>>>> You can have the compiler driver call the linker for you by specifying >>>>>> -o with an output file name. In that case, $CC or $CXX will drive the >>>>>> link. And in this case, your LDFLAGS should prefix options with -Wl to >>>>>> tell the compiler driver the option is for the linker. >>>>>> >>>>>> Jeff >>>>>> >>>>>