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之前已经在MacOS下搭建好了OpenWrt的编译环境，没想到更新到最新的官方Trunk之后，噩梦就此开始。现将思考过程以及应对方法做个记录。
OpenWrt推荐用MacPorts来搭建MacOS中的相关工具。MacOS自带了gcc，版本信息如下：
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn) Target: x86_64-apple-darwin13.4.0 Thread model: posix如果安装了mp-gcc49，则会在/opt/local/bin目录下创建gcc，其版本信息如下：
gcc (MacPorts gcc49 4.9.2_1) 4.9.2 Copyright (C) 2014 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.在搭建编译环境时，可能需要两个gcc切换（一个出错以后，切换另一个使用）。
sudo port install coreutils e2fsprogs ossp-uuid asciidoc binutils bzip2 fastjar flex getopt gtk2 intltool jikes hs-zlib openssl p5-extutils-makemaker python26 subversion rsync ruby sdcc unzip gettext libxslt bison gawk autoconf wget gmake ncurses findutils gnutar mpfr libmpc gcc49说明：mpfr libmpc非必须，系统在编译gcc时，会自动从源码编译这两个库，但如果用llvm-gcc编译时，可能会出现如下错误：
checking for the correct version of the gmp/mpfr/mpc libraries... no configure: error: Building GCC requires GMP 4.2+, MPFR 2.4.0+ and MPC 0.8.0+. Try the --with-gmp, --with-mpfr and/or --with-mpc options to specify
Undefined symbols for architecture x86_64:
"_iconv", referenced from:
convert_using_iconv(void*, unsigned char const*, unsigned long, _cpp_strbuf*) in libcpp.a(charset.o)
(maybe you meant: __Z14cpp_init_iconvP10cpp_reader, __cpp_destroy_iconv )
"_iconv_close", referenced from:
__cpp_destroy_iconv in libcpp.a(charset.o)
__cpp_convert_input in libcpp.a(charset.o)
"_iconv_open", referenced from:
init_iconv_desc(cpp_reader*, char const*, char const*) in libcpp.a(charset.o)
ld: symbol(s) not found for architecture x86_64http://stackoverflow.com/questions/12619600/libiconv-and-macos
macports的libiconv与mac系统的不一致，此时需要做如下修改：
1.切换到mac系统的gcc
2.进入staging_dir/host/usr，创建并进入lib目录，建立/opt/local/lib/中所有libiconv开头的符号链接
Undefined symbols for architecture x86_64:
"_ERR_remove_thread_state", referenced from:
_rsa_sign in rsa-sign.o
ld: symbol(s) not found for architecture x86_64这个问题最为奇怪，网上没有任何地方有对此问题的说明，经过仔细检查错误信息，发现在错误信息之前，有一个
HOSTLDFLAGS=“”
在mkimage的Makefile中，修改
#HOSTLDFLAGS="$(HOST_STATIC_LINKING)" define Host/Compile <span style="white-space:pre"> </span>$(MAKE) -C $(HOST_BUILD_DIR) defconfig <span style="white-space:pre"> </span>$(MAKE) -C $(HOST_BUILD_DIR) <span style="white-space:pre"> </span>HOSTLDFLAGS="-L/opt/local/lib" <span style="white-space:pre"> </span>tools-only endef
ifneq ($(HOST_OS),Darwin)
ifeq ($(CONFIG_BUILD_STATIC_TOOLS),y)
HOST_STATIC_LINKING = -static
endif
endiifneq ($(HOST_OS),Darwin)
ifeq ($(CONFIG_BUILD_STATIC_TOOLS),y)
HOST_STATIC_LINKING = -static
endif
else
HOST_STATIC_LINKING = -L/opt/local/lib
endif在第二个问题的处理上纠缠了很久。看来在MacOS下搭建OpenWrt的编译环境确实是一个比较“蛋疼”的举动
Mac OS下搭建OpenWrt编译环境记录（针对官方最新2015.01.20之trunk）
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原文地址：http://blog.csdn.net/manfeel/article/details/43088363
