[Installation] Fix building using customized TVM path (#1326)

cmake/load_tvm.cmake

@@ -3,12 +3,15 @@
 set(TVM_BUILD_FROM_SOURCE TRUE)
 set(TVM_SOURCE ${CMAKE_SOURCE_DIR}/3rdparty/tvm)
 
-if(DEFINED $ENV{TVM_ROOT})
+if(DEFINED ENV{TVM_ROOT})
   if(EXISTS $ENV{TVM_ROOT}/cmake/config.cmake)
     set(TVM_SOURCE $ENV{TVM_ROOT})
+    message(STATUS "Using TVM_ROOT from environment variable: ${TVM_SOURCE}")
   endif()
 endif()
 
+message(STATUS "Using TVM source: ${TVM_SOURCE}")
+
 set(TVM_INCLUDES
   ${TVM_SOURCE}/include
   ${TVM_SOURCE}/src

docs/get_started/Installation.md

@@ -93,14 +93,16 @@ Some useful CMake options you can toggle while configuring:
 
 (using-existing-tvm)=
 
-### Building with Existing TVM Installation
+### Building with Customized TVM Path
 
-If you already have a compatible TVM installation, use the `TVM_ROOT` environment variable to specify the location of your existing TVM repository when building tilelang:
+If you already have a TVM codebase, use the `TVM_ROOT` environment variable to specify the location of your existing TVM repository when building tilelang:
 
 ```bash
 TVM_ROOT=<your-tvm-repo> pip install . -v
 ```
 
+> **Note**: This will still rebuild the TVM-related libraries (stored in `TL_LIBS`). And this method often leads to some path issues. Check `env.py` to see some environment variables which are not set properly.
+
 (install-using-docker)=
 
 ## Install Using Docker
@@ -197,8 +199,7 @@ Set `NO_TOOLCHAIN_VERSION=ON` to disable this.
 
 ### Run-time environment variables
 
-<!-- TODO: tvm -->
-TODO
+Please refer to the `env.py` file for a full list of supported run-time environment variables.
 
 ## Other Tips
 

tilelang/env.py

@@ -314,9 +314,9 @@ else:
     if tvm_path not in sys.path:
         prepend_pythonpath(tvm_path)
         env.TVM_IMPORT_PYTHON_PATH = tvm_path
-
-    if os.environ.get("TVM_LIBRARY_PATH") is None:
-        os.environ['TVM_LIBRARY_PATH'] = env.TVM_LIBRARY_PATH = os.pathsep.join(TL_LIBS)
+# By default, the built TVM-related libraries are stored in TL_LIBS.
+if os.environ.get("TVM_LIBRARY_PATH") is None:
+    os.environ['TVM_LIBRARY_PATH'] = env.TVM_LIBRARY_PATH = os.pathsep.join(TL_LIBS)
 
 # Initialize CUTLASS paths
 if os.environ.get("TL_CUTLASS_PATH", None) is None: