GCC 降级 / 版本选择

为为为什么

发布于 2024-09-07 13:18:39

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发布于 2024-09-07 13:18:39

文章被收录于专栏：又见苍岚

不同应用可能需要不同版本的 gcc，而且可能遇到gcc 某些版本无法安装的情况，本文记录相关内容。

背景

安装cuda开发库之后，使用gcc编译会可能会报错要求gcc版本，如下表

CUDA version	max supported GCC version
11.1, 11.2, 11.3	10
11	9
10.1, 10.2	8
9.2, 10.0	7
9.0, 9.1	6
8	5.3
7	4.9
5.5, 6	4.8
4.2, 5	4.6
4.1	4.5
4.0	4.4

我当前 gcc 的版本为 11.4, 但是需要安装 gcc 7的版本，但是安装时报错：

> sudo apt install gcc-7 g++-7

Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package g++-7 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

Package gcc-7 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'gcc-7' has no installation candidate
E: Package 'g++-7' has no installation candidate

而且同时我需要兼容保留多个 gcc 版本.

gcc 版本降级

遇到上述错误，原因为：使用的apt镜像库没有这个软件。

解决方案

添加 apt 库

sudo vim /etc/apt/sources.list

在最后添加

# stable add by , in order to install g++7
deb [arch=amd64] http://archive.ubuntu.com/ubuntu focal main universe

更新 apt 库

sudo apt update

重新安装 gcc g++

sudo apt install gcc-7 g++-7

此时已经可以安装了

gcc 版本维护

使用 update-alternatives 设置 gcc 和 g++

update-alternatives 是ubuntu系统中专门维护系统命令链接符的工具，通过它可以很方便的设置系统默认使用哪个命令、哪个软件版本。

查看当前 gcc g++ 版本

ll /usr/bin/gcc*
lrwxrwxrwx 1 root root  6 Aug  5  2021 /usr/bin/gcc -> gcc-11
lrwxrwxrwx 1 root root 23 May 13  2023 /usr/bin/gcc-11 -> x86_64-linux-gnu-gcc-11
lrwxrwxrwx 1 root root 23 May 13  2023 /usr/bin/gcc-12 -> x86_64-linux-gnu-gcc-12
lrwxrwxrwx 1 root root 22 Mar 26  2020 /usr/bin/gcc-7 -> x86_64-linux-gnu-gcc-7
lrwxrwxrwx 1 root root  9 Aug  5  2021 /usr/bin/gcc-ar -> gcc-ar-11
lrwxrwxrwx 1 root root 26 May 13  2023 /usr/bin/gcc-ar-11 -> x86_64-linux-gnu-gcc-ar-11
lrwxrwxrwx 1 root root 26 May 13  2023 /usr/bin/gcc-ar-12 -> x86_64-linux-gnu-gcc-ar-12
lrwxrwxrwx 1 root root 25 Mar 26  2020 /usr/bin/gcc-ar-7 -> x86_64-linux-gnu-gcc-ar-7
lrwxrwxrwx 1 root root  9 Aug  5  2021 /usr/bin/gcc-nm -> gcc-nm-11
lrwxrwxrwx 1 root root 26 May 13  2023 /usr/bin/gcc-nm-11 -> x86_64-linux-gnu-gcc-nm-11
lrwxrwxrwx 1 root root 26 May 13  2023 /usr/bin/gcc-nm-12 -> x86_64-linux-gnu-gcc-nm-12
lrwxrwxrwx 1 root root 25 Mar 26  2020 /usr/bin/gcc-nm-7 -> x86_64-linux-gnu-gcc-nm-7
lrwxrwxrwx 1 root root 13 Aug  5  2021 /usr/bin/gcc-ranlib -> gcc-ranlib-11
lrwxrwxrwx 1 root root 30 May 13  2023 /usr/bin/gcc-ranlib-11 -> x86_64-linux-gnu-gcc-ranlib-11
lrwxrwxrwx 1 root root 30 May 13  2023 /usr/bin/gcc-ranlib-12 -> x86_64-linux-gnu-gcc-ranlib-12
lrwxrwxrwx 1 root root 29 Mar 26  2020 /usr/bin/gcc-ranlib-7 -> x86_64-linux-gnu-gcc-ranlib-7

gcc 已经安装的版本为 12, 11, 7

> ll /usr/bin/g++*
lrwxrwxrwx 1 root root  6 Aug  5  2021 /usr/bin/g++ -> g++-11
lrwxrwxrwx 1 root root 23 May 13  2023 /usr/bin/g++-11 -> x86_64-linux-gnu-g++-11
lrwxrwxrwx 1 root root 23 May 13  2023 /usr/bin/g++-12 -> x86_64-linux-gnu-g++-12
lrwxrwxrwx 1 root root 22 Mar 26  2020 /usr/bin/g++-7 -> x86_64-linux-gnu-g++-7

g++ 已经安装的版本为 12, 11, 7

配置 gcc g++ 的版本优先级

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-12 40 --slave /usr/bin/g++ g++ /usr/bin/g++-12
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-11 50 --slave /usr/bin/g++ g++ /usr/bin/g++-11
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 60 --slave /usr/bin/g++ g++ /usr/bin/g++-7

其中40 ，50 ，60是优先级数值可以自己设定，–slave 能保证 gcc 和 g++ 保持相同的版本。

update-alternatives 配置 gcc 版本

sudo update-alternatives --config gcc

There are 3 choices for the alternative gcc (providing /usr/bin/gcc).

  Selection    Path             Priority   Status
------------------------------------------------------------
* 0            /usr/bin/gcc-7    60        auto mode
  1            /usr/bin/gcc-11   50        manual mode
  2            /usr/bin/gcc-12   40        manual mode
  3            /usr/bin/gcc-7    60        manual mode

Press <enter> to keep the current choice[*], or type selection number:

此时查看 gcc 的版本，可以看到已经变成 7.5.0 的版本

> gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.5.0-6ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-7 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.5.0 (Ubuntu 7.5.0-6ubuntu2)

版本切换

sudo update-alternatives --config gcc

命令执行后，选择 1, 2, 或 3 可以选定当前使用的 gcc g++ 版本，比如我选择了 1

1 的前面会多个星星 *

  Selection    Path             Priority   Status
------------------------------------------------------------
  0            /usr/bin/gcc-7    60        auto mode
* 1            /usr/bin/gcc-11   50        manual mode
  2            /usr/bin/gcc-12   40        manual mode
  3            /usr/bin/gcc-7    60        manual mode

此时 gcc 版本为 11

> gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.4.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-11 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-gcn/usr --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04)

g++ 版本也为 11

> g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.4.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-11 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-gcn/usr --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04)