将 GCC 从 5.2.1 降级到 4.9 Ubuntu 15.10

Question

由于程序兼容性问题，我需要将 GCC 降级到至少 4.9

我该怎么做呢？谢谢。

编辑：该程序是 Blender 并且正在尝试进行 GPU 渲染。控制台踢出的具体错误是

CUDA version 7.5 detected, build may succeed but only CUDA 6.5 is officially supported.
Compiling CUDA kernel ...
"/usr/local/cuda/bin/nvcc" -arch=sm_52 -m64 --cubin "/usr/share/blender/2.76/scripts/addons/cycles/kernel/kernels/cuda/kernel.cu" -o "/home/matthew/.config/blender/2.76/cache/cycles_kernel_sm52_3A157B804910758CA7C526B5EF063D78.cubin" --ptxas-options="-v" --use_fast_math -I"/usr/share/blender/2.76/scripts/addons/cycles/kernel" -DNVCC -D__KERNEL_CUDA_VERSION__=75
In file included from /usr/local/cuda/bin/../targets/x86_64-linux/include/cuda_runtime.h:76:0,
                 from <command-line>:0:
/usr/local/cuda/bin/../targets/x86_64-linux/include/host_config.h:115:2: error: #error -- unsupported GNU version! gcc versions later than 4.9 are not supported!
 #error -- unsupported GNU version! gcc versions later than 4.9 are not supporte
  ^
CUDA kernel compilation failed, see console for details.

Refer to the Cycles GPU rendering documentation for possible solutions:
http://www.blender.org/manual/render/cycles/gpu_rendering.html

Error: CUDA kernel compilation failed, see console for details.`

Answer 1

就像@steeldriver 建议的那样，您需要使用 update-alternatives。正是关于这个问题的第 3 步。由于此时 4.9 是不支持的 4.9.3，因此您需要 4.8。

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 40 --slave /usr/bin/g++ g++ /usr/bin/g++-4.8

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-5 50 --slave /usr/bin/g++ g++ /usr/bin/g++-5

请记住在运行安装程序之前选择 gcc-4.8：

须藤更新替代品 --config gcc

之后，切换回默认使用 gcc-5。

（由于您要安装 CUDA SDK，因此我会补充一点，如果您想测试示例，您可能需要阅读此内容。）