Add Shared Library Build Target

[abetlen]

With the C API now merged it would be very useful to have build targets for make and cmake that produce shared library versions of llama.cpp. This way llama.cpp can just be dynamically linked in other applications.

[thomasantony]

You can already do that by passing in -DLLAMA_STATIC=Off -DBUILD_SHARED_LIBS=On to cmake.

[abetlen]

EDIT: It works but I also needed to add the -DCMAKE_CXX_FLAGS=-fPIC and -DCMAKE_C_FLAGS=-fPIC to avoid the error below.

@thomasantony thanks, I wasn't aware of those flags, however this doesn't seem to be working for me.

Running the following from the llama.cpp root directory

mkdir build
cd build
cmake .. -DLLAMA_STATIC=Off -DBUILD_SHARED_LIBS=On
make

gives me a linking error (maybe I'm missing an additional flag?)

However, if I add a shared library build target to the CMakeLists.txt and run it without the flags everything builds without issue

add_library(llamacpp SHARED
            llama
            ggml)

[Green-Sky]

this is supposed to work, so I'm marking this as a bug.

EDIT: It works but I also needed to add the -DCMAKE_CXX_FLAGS=-fPIC and -DCMAKE_C_FLAGS=-fPIC to avoid the error below.

cmake needs fixing.

you should not need to link against ggml agains here :)

add_library(llamacpp SHARED
            llama
            ggml)

[hanss0n]

I'm still having issues with GLIBC dependencies when compiling this as a library

/usr/bin/ld: CMakeFiles/test-quantize.dir/test-quantize.c.o: undefined reference to symbol 'roundf@@GLIBC_2.2.5' /usr/bin/ld: /lib/x86_64-linux-gnu/libm.so.6: error adding symbols: DSO missing from command line

Any clue if this is also a bug or if I'm missing something? Chain of command is:

mkdir build && cd build
cmake .. -DLLAMA_STATIC=Off -DBUILD_SHARED_LIBS=ON
make

Which fails with this error

[hanss0n]

Seems like something fails with the import of "math.h" intest-quantize

[Green-Sky]

try to link with math (-lm)

[kambo-1st]

Linking with math certainly helps, yet I don't know if this is a proper way:

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 157d733..5767b8b 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,7 +1,7 @@
 function(llama_add_test source)
     get_filename_component(TEST_TARGET ${source} NAME_WE)
     add_executable(${TEST_TARGET} ${source})
-    target_link_libraries(${TEST_TARGET} PRIVATE llama)
+    target_link_libraries(${TEST_TARGET} PRIVATE llama m)
     add_test(NAME ${TEST_TARGET} COMMAND $<TARGET_FILE:${TEST_TARGET}> ${ARGN})
 endfunction()

[Green-Sky]

I wonder why this is only sometimes a problem.

[ghost]

It's worth noting that for me I'm seeing linking issues if using BUILD_SHARED_LIBS with OpenBLAS enabled.

mkdir build && cd build
cmake .. -DLLAMA_STATIC=Off -DBUILD_SHARED_LIBS=ON -DLLAMA_OPENBLAS=ON
make

<REDACTED>:build$ ld libllama.so 
ld: warning: cannot find entry symbol _start; not setting start address
ld: libllama.so: undefined reference to `cblas_sgemm'

OpenBLAS was not linked properly and libllama was not usable. I had to link it in CMakeLists.txt:247 target_link_libraries(llama PRIVATE ggml ${LLAMA_EXTRA_LIBS} openblas) to get libllama.so to properly reference the lib.

[CameronTofer]

I think you need to specify the options before the path. This worked for me:
cmake -DLLAMA_STATIC=Off -DBUILD_SHARED_LIBS=ON -DLLAMA_OPENBLAS=ON ..

[MichaelrMentele]

Dumb question, I'm a C/C++ n00b -- after I run cmake -DLLAMA_STATIC=Off -DBUILD_SHARED_LIBS=ON -DLLAMA_OPENBLAS=ON .. I don't see a library file. How do you statically link an artifact in another project? Trying to link llama.cpp to bindings in an scons project.

[lmbelo]

Dumb question, I'm a C/C++ n00b -- after I run cmake -DLLAMA_STATIC=Off -DBUILD_SHARED_LIBS=ON -DLLAMA_OPENBLAS=ON .. I don't see a library file. How do you statically link an artifact in another project? Trying to link llama.cpp to bindings in an scons project.

The "DBUILD_SHARED_LIBS=ON" option will make it a shared library, so dynamically linked only. If you need to statically link it, set "DBUILD_SHARED_LIBS=OFF" and you'll get a static library file.