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关于gcc的默认搜索路径问题

2013年10月12日 ⁄ 综合 ⁄ 共 9180字 ⁄ 字号 小 中 大 ⁄ 评论关闭
总结下来就一句话：
gcc编译时指定-v参数就能显示详细的信息了。
如：
qj@king:~/test$
qj@king:~/test$ arm-unknown-linux-gnueabi-gcc -o hello hello.c -Wl,-dynamic-linker=/data/app/ld-linux.so.3 -v
Using built-in specs.
Target: arm-unknown-linux-gnueabi
Configured with: /home/qj/crosstool_ng/.build/src/gcc-4.3.2/configure --build=x86_64-build_unknown-linux-gnu --host=x86_64-build_unknown-linux-gnu --target=arm-unknown-linux-gnueabi --prefix=/home/qj/x-tools/arm-unknown-linux-gnueabi --with-sysroot=/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot
--enable-languages=c,c++,fortran,java --with-float=soft --with-pkgversion='crosstool-NG 1.17.0' --disable-sjlj-exceptions --enable-__cxa_atexit --disable-libmudflap --disable-libgomp --disable-libssp --with-gmp=/home/qj/crosstool_ng/.build/arm-unknown-linux-gnueabi/buildtools
--with-mpfr=/home/qj/crosstool_ng/.build/arm-unknown-linux-gnueabi/buildtools --enable-threads=posix --enable-target-optspace --disable-nls --disable-multilib --with-local-prefix=/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot
--enable-c99 --enable-long-long
Thread model: posix
gcc version 4.3.2 (crosstool-NG 1.17.0)
COLLECT_GCC_OPTIONS='-o' 'hello' '-v' '-mfloat-abi=soft'
 /home/qj/x-tools/arm-unknown-linux-gnueabi/libexec/gcc/arm-unknown-linux-gnueabi/4.3.2/cc1 -quiet -v hello.c -quiet -dumpbase hello.c -mfloat-abi=soft -auxbase hello -version -o /tmp/ccNZjE6a.s
ignoring nonexistent directory "/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/include
 /home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/include-fixed
 /home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/../../../../arm-unknown-linux-gnueabi/include
 /home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/usr/include
End of search list.
GNU C (crosstool-NG 1.17.0) version 4.3.2 (arm-unknown-linux-gnueabi)
        compiled by GNU C version 4.6.1, GMP version 4.3.2, MPFR version 2.4.2-p2.
GGC heuristics: --param ggc-min-expand=98 --param ggc-min-heapsize=127776
Compiler executable checksum: f9533e5b1327a97ebc9d3c6220f86781
COLLECT_GCC_OPTIONS='-o' 'hello' '-v' '-mfloat-abi=soft'
 /home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/../../../../arm-unknown-linux-gnueabi/bin/as -mfloat-abi=soft -meabi=4 -o /tmp/ccdGFya4.o /tmp/ccNZjE6a.s
COMPILER_PATH=/home/qj/x-tools/arm-unknown-linux-gnueabi/libexec/gcc/arm-unknown-linux-gnueabi/4.3.2/:/home/qj/x-tools/arm-unknown-linux-gnueabi/libexec/gcc/arm-unknown-linux-gnueabi/4.3.2/:/home/qj/x-tools/arm-unknown-linux-gnueabi/libexec/gcc/arm-unknown-linux-gnueabi/:/home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/:/home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/:/home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/../../../../arm-unknown-linux-gnueabi/bin/
LIBRARY_PATH=/home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/:/home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/../../../../arm-unknown-linux-gnueabi/lib/:/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/lib/:/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/usr/lib/
COLLECT_GCC_OPTIONS='-o' 'hello' '-v' '-mfloat-abi=soft'
 /home/qj/x-tools/arm-unknown-linux-gnueabi/libexec/gcc/arm-unknown-linux-gnueabi/4.3.2/collect2 --sysroot=/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot --eh-frame-hdr -dynamic-linker /lib/ld-linux.so.3 -X -m armelf_linux_eabi
-o hello /home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/usr/lib/crt1.o /home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/usr/lib/crti.o /home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/crtbegin.o
-L/home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2 -L/home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/../../../../arm-unknown-linux-gnueabi/lib -L/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/lib
-L/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/usr/lib /tmp/ccdGFya4.o -dynamic-linker=/data/app/ld-linux.so.3 -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /home/qj/x-tools/arm-unknown-linux-gnueabi/lib/gcc/arm-unknown-linux-gnueabi/4.3.2/crtend.o
/home/qj/x-tools/arm-unknown-linux-gnueabi/arm-unknown-linux-gnueabi/sysroot/usr/lib/crtn.o
----------------------------------------------------------------------------------------------------------------------------------------------------
关于头文件的问题 (2011-05-06 16:49)
分类： 嵌入式Linux

在LINUX程序设计当中，经常会遇到头文件包含的问题，那么这些头文件到底在哪个路径下？具体的头文件路径依赖于程序性质(应用程序还是和内核相关的程序)和编译器，下面分别叙述。

机器环境如下：UBUNTU10.04LTS，自己另外安装的LINUX内核源码目录为/usr/src/kernel，交叉链接器arm-linux-gcc安装目录为/usr/lcoal/arm/2.95.3/

【1.如果是应用程序，并且使用GCC进行普通编译】，如果编译时没有使用-I选项指定包含目录的话，那么默认的头文件目录在/usr/include下，可以在shell下输入如下命令

echo 'main(){}'|gcc
-E -v
-

看到如下输出内容


Using built-in specs.
Target: i486-linux-gnu
Configured with:
../src/configure
-v --with-pkgversion='Ubuntu
4.4.3-4ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++
--prefix=/usr
--enable-shared
--enable-multiarch
--enable-linker-build-id
--with-system-zlib
--libexecdir=/usr/lib
--without-included-gettext
--enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.4
--program-suffix=-4.4
--enable-nls
--enable-clocale=gnu
--enable-libstdcxx-debug
--enable-plugin
--enable-objc-gc
--enable-targets=all
--disable-werror
--with-arch-32=i486
--with-tune=generic
--enable-checking=release
--build=i486-linux-gnu
--host=i486-linux-gnu
--target=i486-linux-gnu
Thread model: posix
gcc version 4.4.3
(Ubuntu 4.4.3-4ubuntu5)

COLLECT_GCC_OPTIONS='-E'
'-v' '-mtune=generic'
'-march=i486'
/usr/lib/gcc/i486-linux-gnu/4.4.3/cc1
-E -quiet
-v - -D_FORTIFY_SOURCE=2
-mtune=generic
-march=i486
-fstack-protector
ignoring nonexistent directory "/usr/local/include/i486-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../i486-linux-gnu/include"
ignoring nonexistent directory "/usr/include/i486-linux-gnu"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/usr/lib/gcc/i486-linux-gnu/4.4.3/include
/usr/lib/gcc/i486-linux-gnu/4.4.3/include-fixed
/usr/include
End of search list.
# 1 "<stdin>"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "<stdin>"
main(){}
COMPILER_PATH=/usr/lib/gcc/i486-linux-gnu/4.4.3/:/usr/lib/gcc/i486-linux-gnu/4.4.3/:/usr/lib/gcc/i486-linux-gnu/:/usr/lib/gcc/i486-linux-gnu/4.4.3/:/usr/lib/gcc/i486-linux-gnu/:/usr/lib/gcc/i486-linux-gnu/4.4.3/:/usr/lib/gcc/i486-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/i486-linux-gnu/4.4.3/:/usr/lib/gcc/i486-linux-gnu/4.4.3/:/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../:/lib/:/usr/lib/:/usr/lib/i486-linux-gnu/
COLLECT_GCC_OPTIONS='-E'
'-v' '-mtune=generic'
'-march=i486'

这就是内定的include文件搜索路径

#include
"..." search starts here:
#include <...> search starts here:
/usr/local/include
/usr/lib/gcc/i486-linux-gnu/4.4.3/include
/usr/lib/gcc/i486-linux-gnu/4.4.3/include-fixed
/usr/include
End of search list.

实际上，这些内定的include文件搜索路径，是存放在specs文件中

【2.如果是应用程序，采用交叉编译】，编译时没有使用-I选项指定包含目录的话，那么默认的头文件搜索路径为/usr/local/arm/2.95.3/arm-linux/include，即交叉编译器的安装目录下的include目录，执行如下命令



echo 'main(){}'|arm-linux-gcc
-E -v
-

看到如下输出内容

Reading specs from
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/specs
gcc version 2.95.3 20010315
(release)
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/cpp0
-lang-c
-v -D__GNUC__=2
-D__GNUC_MINOR__=95
-Dunix -D__arm__
-Dlinux -D__ELF__
-D__unix__ -D__arm__
-D__linux__ -D__ELF__
-D__unix -D__linux
-Asystem(unix)
-Asystem(posix)
-Acpu(arm)
-Amachine(arm)
-D__CHAR_UNSIGNED__
-D__ARM_ARCH_3__ -D__APCS_32__
-
GNU CPP version 2.95.3 20010315
(release)
(ARM GNU/Linux
with ELF)
#include "..." search starts here:
#include <...> search starts here:
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/include
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/../../../../arm-linux/sys-include
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/../../../../arm-linux/include
End of search list.
The following default directories have been omitted from the search
path:
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/../../../../include/g++-3
End of omitted list.
# 1 ""
main(){}

这就是内定的include文件搜索路径

#include
"..." search starts here:
#include <...> search starts here:
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/include
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/../../../../arm-linux/sys-include
/usr/local/arm/2.95.3/lib/gcc-lib/arm-linux/2.95.3/../../../../arm-linux/include
End of search list.

即在采用交叉编译时，应用程序所包含的头文件是在交叉编译器的安装目录下。


【3.如果是和内核相关的程序】,比如驱动程序，那么所包含的头文件是在内核源码的安装目录下，即/usr/src/kernel/include，这时一般要在Makefile文件中指定内核源码目录，在编译时指定INCLUDE目录，可参考“http://blogold.chinaunix.net/u3/119151/showart_2342316.html文章中Makefile文件内容

【4.总结】：
nclude的header文件,连结数据库，系统定义，总共有下列来源指定编译器去那找。
当初在编译时指定的(在~gcc/gcc/collect2.c:locatelib() ，写在specs内的
后来用-D -I -L指定的
gcc环境变量设定(编译的时候)
ld.so的环境变量(这是run time的时候）

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