[Bug] Cannot find -lxml2 when linking libtvm.so on Ubuntu 22.04 (WSL2)

[930727fre]

Expected behavior

TVM should successfully compile and link libtvm.so without missing -lxml2.

Actual behavior

The build fails with a linker error stating that -lxml2 cannot be found:

[100%] Building CXX object CMakeFiles/tvm_objs.dir/src/target/llvm/llvm_instance.cc.o
[100%] Building CXX object CMakeFiles/tvm_objs.dir/src/target/llvm/llvm_module.cc.o
/home/fre930727/tvm/src/target/tag.cc: In function ‘void __static_initialization_and_destruction_0(int, int)’:
/home/fre930727/tvm/src/target/tag.cc:462:1: note: variable tracking size limit exceeded with ‘-fvar-tracking-assignments’, retrying without
  462 | }  // namespace tvm
      | ^
[100%] Built target tvm_objs
[100%] Linking CXX shared library libtvm.so
[100%] Linking CXX shared library libtvm_allvisible.so
/usr/bin/ld: cannot find -lxml2: /usr/bin/ld: cannot find -lxml2: No such file or directory
No such file or directory
collect2: error: ld returned 1 exit status
collect2: error: ld returned 1 exit status
gmake[2]: *** [CMakeFiles/tvm.dir/build.make:1408: libtvm.so] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:208: CMakeFiles/tvm.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....
gmake[2]: *** [CMakeFiles/tvm_allvisible.dir/build.make:1408: libtvm_allvisible.so] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:309: CMakeFiles/tvm_allvisible.dir/all] Error 2
gmake: *** [Makefile:136: all] Error 2

Environment

• OS: Ubuntu 22.04 (WSL2)
• CPU: Intel i5-12400
• TVM Version: 12e72c2

Steps to reproduce

1. Follow the instructions in the [TVM installation guide](https://tvm.apache.org/docs/install/from_source.html).

2. Execute the following shell script:

   # make sure to start with a fresh environment
   conda env remove -n tvm-build-venv
   # create the conda environment with build dependency
   conda create -n tvm-build-venv -c conda-forge \
       "llvmdev>=15" \
       "cmake>=3.24" \
       git \
       python=3.11
   # enter the build environment
   conda activate tvm-build-venv

   git clone --recursive https://github.com/apache/tvm tvm
   

   cd tvm
   rm -rf build && mkdir build && cd build
   # Specify the build configuration via CMake options
   cp ../cmake/config.cmake .

   # controls default compilation flags (Candidates: Release, Debug, RelWithDebInfo)
   echo "set(CMAKE_BUILD_TYPE RelWithDebInfo)" >> config.cmake
   
   # LLVM is a must dependency for compiler end
   echo "set(USE_LLVM \"llvm-config --ignore-libllvm --link-static\")" >> config.cmake
   echo "set(HIDE_PRIVATE_SYMBOLS ON)" >> config.cmake
   
   # GPU SDKs, turn on if needed
   echo "set(USE_CUDA   OFF)" >> config.cmake
   echo "set(USE_METAL  OFF)" >> config.cmake
   echo "set(USE_VULKAN OFF)" >> config.cmake
   echo "set(USE_OPENCL OFF)" >> config.cmake
   
   # cuBLAS, cuDNN, cutlass support, turn on if needed
   echo "set(USE_CUBLAS OFF)" >> config.cmake
   echo "set(USE_CUDNN  OFF)" >> config.cmake
   echo "set(USE_CUTLASS OFF)" >> config.cmake

   cmake .. && cmake --build . --parallel $(nproc)

3. The build fails with the above linker error.

Troubleshooting Attempts

• Added debugging options:

  echo "set(CMAKE_BUILD_TYPE Debug)" >> config.cmake
  echo "set(USE_ALTERNATIVE_LINKER OFF)" >> config.cmake
  echo "set(USE_LIBBACKTRACE On)" >> config.cmake
  

• Installed libxml2 via Conda:

  conda install -c conda-forge libxml2
  

Questions

• Is libxml2 required to be installed via apt rather than Conda for TVM to find it?
• Are there specific CMake flags I should set to properly link against libxml2?
• Any recommendations for debugging linker issues in this context?

Triage

• needs-triage

Any help would be greatly appreciated. Thanks!

[ShihengCao]

hello, i encoutered the same problem and i resolved it. My solution is use the path of xml2 to replace the -lxml2 in link.txt.
use bash:~$ find $CONDA_PREFIX/lib -name "libxml2*" to get the path of lxml2.
I get a path like /$HOME/miniconda3/envs/tvm-build-venv/lib/libxml2.so, then use "/$HOME/miniconda3/envs/tvm-build-venv/lib/libxml2.so" to replace "-lxml2" in tvm/build/CMakeFiles/tvm_allvisible.dir/link.txt and tvm/build/CMakeFiles/tvm.dir/link.txt.
Hope this can work for you.

[930727fre]

Hi, I've tried your solution (thanks for providing so much information). However, it still failed in the process. What comes to my mind after that is conda's environment path and WSL's path may probably lead to wrong path, so I re-create a Ubuntu 22.04 VM on virtual box without using conda then all the hassle were cleared. Thanks for your help again!