如何在高山上編譯一個32位的hello世界？

Question

給出一個簡單的hello world代碼：

#include <stdio.h>
int main(void){
  puts("hello");
  return 0;
}

在64位alpine linux安裝上，我嘗試將其編譯為64位和32位。 第一個工作正常，但第二個缺少32位庫：

~ # gcc -Wall hello.c 
~ # gcc -Wall -m32 hello.c 
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../libssp_nonshared.a when searching for -lssp_nonshared
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible //usr/lib/libssp_nonshared.a when searching for -lssp_nonshared
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lssp_nonshared
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/libgcc.a when searching for -lgcc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lgcc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../libgcc_s.so when searching for -lgcc_s
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible //usr/lib/libgcc_s.so when searching for -lgcc_s
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lgcc_s
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../libc.so when searching for -lc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../libc.a when searching for -lc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible //usr/lib/libc.so when searching for -lc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible //usr/lib/libc.a when searching for -lc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/libgcc.a when searching for -lgcc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lgcc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../libgcc_s.so when searching for -lgcc_s
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible //usr/lib/libgcc_s.so when searching for -lgcc_s
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lgcc_s
collect2: error: ld returned 1 exit status

因為我沒有找到解決這個問題的明顯方法，所以我將32位版本的gcc，libgcc和musl-dev解​​壓縮到本地目錄並設置了LIBRARY_PATH：

~ # LIBRARY_PATH=usr/lib/gcc/i586-alpine-linux-musl/5.3.0:usr/lib gcc -Wall -m32 hello.c 
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/libgcc.a when searching for -lgcc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/libgcc.a when searching for -lgcc
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: i386:x86-64 architecture of input file `/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/crtbeginS.o' is incompatible with i386 output
/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: i386:x86-64 architecture of input file `/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/crtendS.o' is incompatible with i386 output
collect2: error: ld returned 1 exit status
~ # 

這部分修復了問題，但gcc仍然首先嘗試64位庫，並試圖找到64位crt文件。

那么在alpine linux上編譯32位二進制文​​件的正確方法是什么？

---

為了使最后一個問題更清楚，請看這個：

~ # LIBRARY_PATH=/tmp gcc --verbose -Wall -m32 hello.c 2>&1|grep LIBRARY_PATH
LIBRARY_PATH=/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/:/tmp/:/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/lib/:/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../:/lib/:/usr/lib/

如果我只設置了一些LIBRARY_PATH，編譯器會在內部添加其他目錄。 特別是它還預裝了“錯誤的”系統目錄，其中包含64位庫。 因此它使用了錯誤的crt libs，因此使用了上面的最后一個錯誤。

我要么需要正確的alpine包（而不關心它是如何工作的），要么我需要了解如何更改gcc內部添加的第一條路徑。

Answer 1

根據gcc -v對alpine gcc的編譯沒有multilib支持：

--disable-multilib

在debian上啟用multilib時：

--with-multilib-list=m32,m64,mx32 --enable-multilib

需要Multilib支持才能使-m32可靠地工作。 因此，alpine上的默認編譯器實際上不適合編譯32位二進制文​​件。