LFS第6.18章gcc-pass2编译失败：x86_64-lfs-linux-gnu-gcc未找到

问题描述 #

我在进行LFS（Linux From Scratch）stable-systemd版本第6.18章的gcc-pass2编译时，执行x86_64-lfs-linux-gnu-gcc -dumpspecs > tmp-specs命令时提示x86_64-lfs-linux-gnu-gcc: command not found，最终导致make执行失败。

错误日志 #

g++ -fno-PIE -c -g -O2 -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -DHAVE_CONFIG_H -I. -I. -I../.././gcc -I../.././gcc/. -I../.././gcc/../include -I../.././gcc/../libcpp/include -I../.././gcc/../libcody -I/mnt/lfs/sources/gcc-12.2.0/host-x86_64-lfs-linux-gnu/gmp -I/mnt/lfs/sources/gcc-12.2.0/gmp -I/mnt/lfs/sources/gcc-12.2.0/host-x86_64-lfs-linux-gnu/mpfr/src -I/mnt/lfs/sources/gcc-12.2.0/mpfr/src -I/mnt/lfs/sources/gcc-12.2.0/mpc/src -I../.././gcc/../libdecnumber -I../.././gcc/../libdecnumber/dpd -I../libdecnumber -I../.././gcc/../libbacktrace -o insn-recog.o -MT insn-recog.o -MMD -MP -MF ./.deps/insn-recog.TPo insn-recog.cc
x86_64-lfs-linux-gnu-gcc -dumpspecs > tmp-specs
/bin/sh: line 1: x86_64-lfs-linux-gnu-gcc: command not found
make[2]: *** [Makefile:2185: specs] Error 127 
make[2]: *** Waiting for unfinished jobs.... 
rm gcc.pod 
make[2]: Leaving directory '/mnt/lfs/sources/gcc-12.2.0/host-x86_64-lfs-linux-gnu/gcc'
make[1]: *** [Makefile:4621: all-gcc] Error 2
make[1]: Leaving directory '/mnt/lfs/sources/gcc-12.2.0'
make: *** [Makefile:1036: all] Error 2

编译函数 #

function gcc2() {
    export BUILD_DIR=/mnt/lfs/sources ## This si usualy at top of file but added it for this examples sake.
    #https://linuxfromscratch.org/lfs/view/stable-systemd/chapter06/gzip.html
    cd $BUILD_DIR && tar -vxkf gcc-12.2.0.tar.xz && cd gcc-12.2.0
    $BUILD_DIR/gcc-12.2.0/contrib/download_prerequisites
    rm -rf $BUILD_DIR/gcc-12.2.0/isl*
    case $(uname -m) in
        x86_64)
            sed -e '/m64=/s/lib64/lib/' -i.orig $BUILD_DIR/gcc-12.2.0/gcc/config/i386/t-linux64
        ;;
    esac
    sed '/thread_header =/s/@.*@/gthr-posix.h/' -i $BUILD_DIR/gcc-12.2.0/libgcc/Makefile.in libstdc++-v3/include/Makefile.in
    if ! [[ -d "$BUILD_DIR/gcc-12.2.0/build" ]]; then
        mkdir $BUILD_DIR/gcc-12.2.0/build && cd $BUILD_DIR/gcc-12.2.0/build
    fi
    $BUILD_DIR/gcc-12.2.0/build/../configure --build=$(../config.guess) --host=$LFS_TGT --target=$LFS_TGT LDFLAGS_FOR_TARGET=-L$PWD/$LFS_TGT/libgcc --prefix=/usr --with-build-sysroot=$LFS --enable-initfini-array --disable-nls --disable-multilib --disable-decimal-float --disable-libatomic --disable-libgomp --disable-libquadmath --disable-libssp --disable-libvtv --enable-languages=c,c++
    make && make DESTDIR=$LFS install && ln -sv gcc $LFS/usr/bin/cc
}

环境变量 #

lfs:/mnt/lfs/sources/gcc-12.2.0$ env
PWD=/mnt/lfs/sources/gcc-12.2.0
HOME=/home/lfs
MAKEFLAGS=-j8
TERM=screen
SHLVL=1
PS1=\u:\w\$
LFS_TGT=x86_64-lfs-linux-gnu
LC_ALL=POSIX
LFS=/mnt/lfs
CONFIG_SITE=/mnt/lfs/usr/share/config.site
PATH=/mnt/lfs/tools/bin:/usr/bin
_=/usr/bin/env
OLDPWD=/mnt/lfs/sources/gcc-12.2.0/build
lfs:/mnt/lfs/sources/gcc-12.2.0$

问题原因及解决方法 #

核心原因 #

交叉编译器x86_64-lfs-linux-gnu-gcc未被系统找到，要么是gcc-pass1未正确安装到/mnt/lfs/tools/bin目录，要么是编译过程中路径逻辑存在问题。

排查与修复步骤 #

1. 检查交叉编译器是否存在
   执行以下命令确认/mnt/lfs/tools/bin下是否有目标编译器：

   ls -l /mnt/lfs/tools/bin/x86_64-lfs-linux-gnu-gcc
   

   如果输出不存在，说明gcc-pass1编译安装失败，需回到LFS第5章重新完成gcc-pass1的编译与安装。

2. 修正编译函数的路径逻辑
   原函数中，若build目录已存在，不会执行cd命令，导致后续configure在错误路径执行。修改为强制进入build目录：

   mkdir -p $BUILD_DIR/gcc-12.2.0/build && cd $BUILD_DIR/gcc-12.2.0/build
   

   （mkdir -p确保目录存在，无论是否已创建）

3. 清理后重新编译
   清理现有build目录，重新执行configure和make：

   rm -rf $BUILD_DIR/gcc-12.2.0/build
   mkdir -p $BUILD_DIR/gcc-12.2.0/build && cd $_
   ../configure --build=$(../config.guess) --host=$LFS_TGT --target=$LFS_TGT LDFLAGS_FOR_TARGET=-L$PWD/$LFS_TGT/libgcc --prefix=/usr --with-build-sysroot=$LFS --enable-initfini-array --disable-nls --disable-multilib --disable-decimal-float --disable-libatomic --disable-libgomp --disable-libquadmath --disable-libssp --disable-libvtv --enable-languages=c,c++
   make
   

内容的提问来源于stack exchange，提问作者Definity