Peter Smith via llvm-dev
2016-Nov-02 09:52 UTC
[llvm-dev] Cross-compiling for ARM on x86 with llvm/Clang
Hello, Without going into too much detail I think the basic problem is that when you use gcc as the linker driver you are using the linker from aarch64-linux-gnu which will include the GNU linker supporting aarch64 and the aarch64 libraries. When you set the sysroot to arm-linux-gnueabi you are using the aarch32 sysroot which won't include the libraries and linker needed for aarch64. It will be worth finding out the sysroot that aarch64-linux-gnu-gcc is using and use that instead. Peter On 2 November 2016 at 07:49, via llvm-dev <llvm-dev at lists.llvm.org> wrote:> Hello list > > I have some problems when using x86 cross-compile the arm progress. > > > > First I know a way to get aarch64 binary in x86 with llvm/clang. > > There need two things prepared for cross-compile. > > 1. GUN ARM toolchain à apt-get install gcc-arm-linux-gnueabi > > 2. Clang/llvm compile à http://clang.llvm.org/get_started.html > > > > clang -emit-llvm -target aarch64 helloworld.c -I > /usr/aarch64-linux-gnu/include -c > > (can get helloworld.bc) > > llc helloworld.bc -o helloworld.s > > aarch64-linux-gnu-gcc helloworld.s -o helloworld > > > > From the cmd above, I can get the aarch64 binary which is function well in > aarch64 machine. > > But, Is there other way that I can get aarch64 without gcc. > > > > When I try to use below: > > clang -v -target arm-linux-gnueabi --sysroot=/usr/arm-linux-gnueabi/ > helloworld.c -o hello > > > > I get: > > Obfuscator-LLVM clang version 3.6.1 (tags/RELEASE_361/final) (based on > Obfuscator-LLVM 3.6.1) > > Target: arm--linux-gnueabi > > Thread model: posix > > "/usr/local/bin/clang-3.6" -cc1 -triple armv4t--linux-gnueabi -emit-obj > -mrelax-all -disable-free -disable-llvm-verifier -main-file-name arm.c > -mrelocation-model static -mthread-model posix -mdisable-fp-elim > -fmath-errno -masm-verbose -mconstructor-aliases -target-cpu arm7tdmi > -target-feature +soft-float-abi -target-abi aapcs-linux -mfloat-abi soft -v > -dwarf-column-info -resource-dir /usr/local/bin/../lib/clang/3.6.1 -isysroot > /usr/arm-linux-gnueabi/ -internal-isystem > /usr/arm-linux-gnueabi//usr/local/include -internal-isystem > /usr/local/bin/../lib/clang/3.6.1/include -internal-externc-isystem > /usr/arm-linux-gnueabi//include -internal-externc-isystem > /usr/arm-linux-gnueabi//usr/include -fdebug-compilation-dir > /home/zyj/Desktop -ferror-limit 19 -fmessage-length 80 -mstackrealign > -fno-signed-char -fobjc-runtime=gcc -fdiagnostics-show-option > -fcolor-diagnostics -o /tmp/helloworld-6b36a6.o -x c helloworld.c > > clang -cc1 version 3.6.1 based upon Obfuscator-LLVM 3.6.1 default target > i386-pc-linux-gnu > > ignoring nonexistent directory "/usr/arm-linux-gnueabi//usr/local/include" > > ignoring nonexistent directory "/usr/arm-linux-gnueabi//usr/include" > > #include "..." search starts here: > > #include <...> search starts here: > > /usr/local/bin/../lib/clang/3.6.1/include > > /usr/arm-linux-gnueabi//include > > End of search list. > > "/usr/local/bin/ld" --sysroot=/usr/arm-linux-gnueabi/ -z relro -X > --hash-style=gnu --build-id --eh-frame-hdr -m armelf_linux_eabi > -dynamic-linker /lib/ld-linux.so.3 -o hello > /usr/arm-linux-gnueabi//lib/../lib/crt1.o > /usr/arm-linux-gnueabi//lib/../lib/crti.o crtbegin.o > -L/usr/arm-linux-gnueabi//lib/../lib -L/usr/arm-linux-gnueabi//lib > /tmp/helloworld-6b36a6.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc > --as-needed -lgcc_s --no-as-needed crtend.o > /usr/arm-linux-gnueabi//lib/../lib/crtn.o > > /usr/local/bin/ld: unrecognised emulation mode: armelf_linux_eabi > > Supported emulations: elf_i386 i386linux elf32_x86_64 elf_x86_64 elf_l1om > elf_k1om i386pep i386pe > > clang-3.6: error: linker command failed with exit code 1 (use -v to see > invocation) > > > > This seems that linker is wrong, so I change the ld point to > /usr/arm-linux-gnueabi/bin/ld > > (using: ln -s /usr/arm-linux-gnueabi/bin/ld ld) > > > > But I get anther question > > > > Obfuscator-LLVM clang version 3.6.1 (tags/RELEASE_361/final) (based on > Obfuscator-LLVM 3.6.1) > > Target: arm--linux-gnueabi > > Thread model: posix > > "/usr/local/bin/clang-3.6" -cc1 -triple armv4t--linux-gnueabi -emit-obj > -mrelax-all -disable-free -disable-llvm-verifier -main-file-name arm.c > -mrelocation-model static -mthread-model posix -mdisable-fp-elim > -fmath-errno -masm-verbose -mconstructor-aliases -target-cpu arm7tdmi > -target-feature +soft-float-abi -target-abi aapcs-linux -mfloat-abi soft -v > -dwarf-column-info -resource-dir /usr/local/bin/../lib/clang/3.6.1 -isysroot > /usr/arm-linux-gnueabi/ -internal-isystem > /usr/arm-linux-gnueabi//usr/local/include -internal-isystem > /usr/local/bin/../lib/clang/3.6.1/include -internal-externc-isystem > /usr/arm-linux-gnueabi//include -internal-externc-isystem > /usr/arm-linux-gnueabi//usr/include -fdebug-compilation-dir > /home/zyj/Desktop -ferror-limit 19 -fmessage-length 80 -mstackrealign > -fno-signed-char -fobjc-runtime=gcc -fdiagnostics-show-option > -fcolor-diagnostics -o /tmp/helloworld-fa5b7f.o -x c helloworld.c > > clang -cc1 version 3.6.1 based upon Obfuscator-LLVM 3.6.1 default target > i386-pc-linux-gnu > > ignoring nonexistent directory "/usr/arm-linux-gnueabi//usr/local/include" > > ignoring nonexistent directory "/usr/arm-linux-gnueabi//usr/include" > > #include "..." search starts here: > > #include <...> search starts here: > > /usr/local/bin/../lib/clang/3.6.1/include > > /usr/arm-linux-gnueabi//include > > End of search list. > > "/usr/local/bin/ld" --sysroot=/usr/arm-linux-gnueabi/ -z relro -X > --hash-style=gnu --build-id --eh-frame-hdr -m armelf_linux_eabi > -dynamic-linker /lib/ld-linux.so.3 -o hello > /usr/arm-linux-gnueabi//lib/../lib/crt1.o > /usr/arm-linux-gnueabi//lib/../lib/crti.o crtbegin.o > -L/usr/arm-linux-gnueabi//lib/../lib -L/usr/arm-linux-gnueabi//lib > /tmp/helloworld-fa5b7f.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc > --as-needed -lgcc_s --no-as-needed crtend.o > /usr/arm-linux-gnueabi//lib/../lib/crtn.o > > /usr/local/bin/ld: cannot find crtbegin.o: No such file or directory > > /usr/local/bin/ld: cannot find -lgcc > > /usr/local/bin/ld: cannot find -lgcc_s > > /usr/local/bin/ld: cannot find /usr/arm-linux-gnueabi/lib/libc.so.6 inside > /usr/arm-linux-gnueabi/ > > /usr/local/bin/ld: cannot find /usr/arm-linux-gnueabi/lib/libc_nonshared.a > inside /usr/arm-linux-gnueabi/ > > /usr/local/bin/ld: cannot find /usr/arm-linux-gnueabi/lib/ld-linux.so.3 > inside /usr/arm-linux-gnueabi/ > > clang-3.6: error: linker command failed with exit code 1 (use -v to see > invocation) > > > > From above message I am confused about the: > > /usr/local/bin/ld: cannot find crtbegin.o: No such file or directory > > /usr/local/bin/ld: cannot find -lgcc > > /usr/local/bin/ld: cannot find -lgcc_s > > /usr/local/bin/ld: cannot find /usr/arm-linux-gnueabi/lib/libc.so.6 inside > /usr/arm-linux-gnueabi/ > > /usr/local/bin/ld: cannot find /usr/arm-linux-gnueabi/lib/libc_nonshared.a > inside /usr/arm-linux-gnueabi/ > > /usr/local/bin/ld: cannot find /usr/arm-linux-gnueabi/lib/ld-linux.so.3 > inside /usr/arm-linux-gnueabi/ > > > > While all these lib is at the right location, why error says ld cannot find > them. > > If you need more imformation from me, please let me know. > > Thanks > > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >