Problems building latest headless CUDA on linux: can't find acceptable g++ version

Building Blender
#1

Hi folks; I’m trying to build the latest master e4932d1167f on linux WSL Ubuntu 18.04, using the recommended CUDA toolkit v10.2.
I want to build headless with CUDA support for Cycles. So in CMakeLists.txt I turn on WITH_CYCLES_CUDA_BINARIES and run make headless (after removing previous build).
The problem I’m having is related to gcc/g++ versions.

If I use gcc/g++ 7.x or 8.x, I get this error during initial config:

CMake Error at build_files/cmake/platform/platform_unix.cmake:42 (message):
  GCC version must be at least 9.3 for precompiled libraries, found 8.4.0

but if I use gcc/g++ 9.x, I get this error instead, during the build:

/usr/local/cuda-10.2/bin/../targets/x86_64-linux/include/crt/host_config.h:138:2: 
error: -- unsupported GNU version! gcc versions later than 8 are not supported!

Seems like I can’t win! This doc says to use CUDA toolkit 10.1 or 10.2, “later versions may not work” so I didn’t try 11 yet.

I’ve updated my deps (make update), cleaned out everything I can think of. Anyone doing this successfully and have a recipe for me?

#2

Try building Blender with gcc 9 and CUDA with gcc 8.
For Blender, do the usual version switch to gcc 9. For Cuda, change the gcc version only in its CMakeCache.txt file.

Building Blender with CUDA on CentOS - gcc Version?
#3

Thanks – I’m not sure exactly which CMakeCache.txt you mean. I can see one failure is when it’s trying to build intern/cycles/kernel/filter_sm_30.cubin for instance.
I believe that’s built using ../build_linux_headless/intern/cycles/kernel/CMakeFiles/cycles_kernel_cuda.dir/build.make but I don’t see a related cache file for that – I’m not a cmake expert at all (though I’ve done CUDA development for a few years); maybe you can walk me through it?

Right now I’ve set gcc-9 as the default using sudo update-alternatives --config gcc.

#4

I picked that from the third link I posted.

I’m guessing there is an entry for path to Cuda compiler in the CMakeCache.txt file in the build folder. If it points to gcc-9, change the path manually to 8.

If doesn’t work, try the second link (last post in that thread) or the fourth one which use symlink
ln -sf /usr/bin/gcc-8 /usr/local/cuda/bin/gcc

1 Like
#5

The symlink should work I think.

Other possible solutions are to set WITH_CYCLES_CUBIN_COMPILER to ON, or to modify CUDA_NVCC_EXECUTABLE and use the -ccbin argument to point to a specific g++ version.

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#6

The way CUDA_NVCC_EXECUTABLE is set up, you can’t add args to it without causing errors. And WITH_CYCLES_CUBIN_COMPILER gives the same error about gcc version.
But the symlink seems to be working – what a hack, but OK!
Going to try adding Optix next…

qq: is there a build option to see the actual compile/link command lines being executed? A bit hard to debug without those.

#7

It can be seen with Ninja generator by building with ninja -v.

#8

For those having problems with GCC version on Ubuntu 18.04 when compiling:
GCC version must be at least 9.3 for precompiled libraries, found 7.5.0

luckily I found this great tutorial on how to install GCC 9 (PPA currently has GCC 10 version too, but for now 9 version is enough for blender):

You follow all the steps from start to the end (“Compiling a Hello World Example” can be skipped).

Still, “Remove compatibility checks” may be necessary if we have build errors related to CUDA and GCC version:

Blender 2.90 Local build fails