Build error

[dingrui37]

I have cloned the latest version of p4c, then install all dependencies. However, when building the project, it always gives an error.

mkdir build
cd build
cmake ..     // cmake error

The command console outputs as follows,

..........
-- Using the GNU gold linker.
-- Available extensions
-- Added 307 tests to 'bmv2' (8 xfails)
-- Added 4 tests to 'bmv2' (4 xfails)
CMake Warning at backends/ebpf/CMakeLists.txt:99 (MESSAGE):
  Kernel version 4.13.0 too small, expected 4.15.0.  Ignoring ebpf kernel
  tests...

CMake Error at /usr/share/llvm-3.8/cmake/LLVMConfig.cmake:178 (include):
  include could not find load file:

    /usr/share/llvm/cmake/LLVMExports.cmake
Call Stack (most recent call first):
  backends/ebpf/CMakeLists.txt:108 (find_package)


CMake Error at /usr/share/llvm-3.8/cmake/LLVMConfig.cmake:181 (include):
  include could not find load file:

    /usr/share/llvm/cmake/LLVM-Config.cmake
Call Stack (most recent call first):
  backends/ebpf/CMakeLists.txt:108 (find_package)

-- Found LLVM 3.8.0
-- Added 13 tests to 'ebpf-bcc' (0 xfails)
-- Added 13 tests to 'ebpf' (0 xfails)
-- Added 154 tests to 'p4' (0 xfails)
-- Added 440 tests to 'p4' (1 xfails)
-- Added 195 tests to 'p14_to_16' (0 xfails)
-- CTest parallel: -j 12
-- Configuring incomplete, errors occurred!
See also "/home/workspace/p4lang/p4c/build/CMakeFiles/CMakeOutput.log".
See also "/home/workspace/p4lang/p4c/build/CMakeFiles/CMakeError.log".

CMakeError.log:

/usr/bin/cc       CMakeFiles/cmTC_f12d2.dir/CheckSymbolExists.c.o  -o cmTC_f12d2 -rdynamic
CMakeFiles/cmTC_f12d2.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text+0x16): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_f12d2.dir/build.make:97: recipe for target 'cmTC_f12d2' failed
make[1]: *** [cmTC_f12d2] Error 1
make[1]: Leaving directory '/home/workspace/p4lang/p4c/build/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_f12d2/fast' failed
make: *** [cmTC_f12d2/fast] Error 2

File /home/workspace/p4lang/p4c/build/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef pthread_create
  return ((int*)(&pthread_create))[argc];
#else
  (void)argc;
  return 0;
#endif
}

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/workspace/p4lang/p4c/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_1a26c/fast"
/usr/bin/make -f CMakeFiles/cmTC_1a26c.dir/build.make CMakeFiles/cmTC_1a26c.dir/build
make[1]: Entering directory '/home/workspace/p4lang/p4c/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_1a26c.dir/CheckFunctionExists.c.o
/usr/bin/cc    -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_1a26c.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.5/Modules/CheckFunctionExists.c
Linking C executable cmTC_1a26c
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_1a26c.dir/link.txt --verbose=1
/usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create    CMakeFiles/cmTC_1a26c.dir/CheckFunctionExists.c.o  -o cmTC_1a26c -rdynamic -lpthreads
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_1a26c.dir/build.make:97: recipe for target 'cmTC_1a26c' failed
make[1]: *** [cmTC_1a26c] Error 1
make[1]: Leaving directory '/home/workspace/p4lang/p4c/build/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_1a26c/fast' failed
make: *** [cmTC_1a26c/fast] Error 2

BTW: I can call pthread_create successfully in my local environment.(e.g. gcc -o test test.c -lpthreads)

[hesingh]

Ding,

Did you do a “sudo apt-get install llvm” on your machine? New p4c has added a llvm dependency. I downloaded latest p4c right now and ‘cmake ..’ runs fine for me. My machine is using a 4.15.0 kernel and I use Ubuntu 18.04. Your kernel is 4.13.0 and I also see some llvm issues in your log.

Hemant

[mihaibudiu]

This is probably the same as #1376.
This is quite annoying, but I don't know what other workarounds to propose than the ones in that issue.

[cc10512]

How about turning off the EBPF backend by default until you solve these issues? (Set ENABLE_EBPF to OFF in CMakeLists.txt:34)

[dingrui37]

@mbudiu-vmw I have solved the problem temporarily according to Antonin's method. But it does not seem like a perfect solution.
cmake .. -DENABLE_EBPF=OFF