Android编译环 境中应用了out/host/linux-x86/bin/soslim工具进行STRIP

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build/core/product_config.mk:229: WARNING: adding test OTA key

out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/LINKED/helloworld: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped
out/host/linux-x86/bin/acp -fpt out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/helloworld out/target/product/generic/system/bin/helloworld

# prebuilt/linux-x86/toolchain/arm-eabi-4.2.1/bin/arm-eabi-gcc -nostdlib -Bdynamic -Wl,-T,build/core/armelf.x -Wl,-dynamic-linker,/system/bin/linker -Wl,--gc-sections -Wl,-z,nocopyreloc -o out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/LINKED/helloworld -Lout/target/product/generic/obj/lib -Wl,-rpath-link=out/target/product/generic/obj/lib -lc -lm  out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/hello.o out/target/product/generic/obj/lib/crtbegin_dynamic.o -Wl,--no-undefined ./prebuilt/linux-x86/toolchain/arm-eabi-4.2.1/bin/../lib/gcc/arm-eabi/4.2.1/interwork/libgcc.a out/target/product/generic/obj/lib/crtend_android.o
# rm out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/hello.o
0x00000001 (NEEDED)                     Shared library: [libm.so]
这是ARM格局的动态链接可执行文件，运行时须要libc.so和libm.so。“not stripped”
表现它还没被STRIP。嵌入式体系中为节
省空间通常将编译实现的可执行文件或动态库进行STRIP，即去掉其中过剩的符号表信息。在前面“make helloworld showcommands”命令的最后我们也可以看到，Android编译环
境中使用了out/host/linux-x86/bin/soslim工具进行STRIP。
上一篇中（即《编译Native C的helloworld模块》），我们试用了通过尺度的Android.mk文件来编译C模块，下面我们来尝尝如何直接应用gcc命令行来编译，从而懂得Android编译环
境的细节。
target Strip: helloworld (out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/helloworld)
有关Android Toolchain的其余一些内容可参考：Android Toolchain与Bionic Libc

上面的“make clean-$(LOCAL_MODULE)”是Android编译环境提供的make clean的方法。
与Android.mk编译参数比拟，上面重要减少了不用要的-I参数。
Install: out/target/product/generic/system/bin/helloworld
target Non-prelinked: helloworld (out/target/product/generic/symbols/system/bin/helloworld)

out/host/linux-x86/bin/soslim --strip --shady --quiet out/target/product/generic/symbols/system/bin/helloworld --outfile out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/helloworld
天生的可履行程序可用file跟readelf命令来查看一下：

# file out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/LINKED/helloworld

我们可以应用上面的编译命令，稍加简化来手工编译helloworld程序。先手工删除上次编
译得到的helloworld程序：

# rm out/target/product/generic/system/bin/helloworld
# make clean-helloworld
接下来生成可执行文件：
# prebuilt/linux-x86/toolchain/arm-eabi-4.2.1/bin/arm-eabi-gcc -I bionic/libc/arch-arm/include -I bionic/libc/include -I bionic/libc/kernel/common   -I bionic/libc/kernel/arch-arm -c  -fno-exceptions -Wno-multichar -march=armv5te -mtune=xscale -msoft-float -fpic -mthumb-interwork -ffunction-sections -funwind-tables -fstack-protector -D__ARM_ARCH_5__ -D__ARM_ARCH_5T__ -D__ARM_ARCH_5E__ -D__ARM_ARCH_5TE__ -include system/core/include/arch/linux-arm/AndroidConfig.h -DANDROID -fmessage-length=0 -W -Wall -Wno-unused -DSK_RELEASE -DNDEBUG -O2 -g -Wstrict-aliasing=2 -finline-functions -fno-inline-functions-called-once -fgcse-after-reload -frerun-cse-after-loop -frename-registers -DNDEBUG -UDEBUG -mthumb -Os -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64      -MD -o out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/hello.o development/hello/hello.c
这里值得留心的是参数“-Wl,-dynamic-linker,/system/bin/linker”，它指定了Android专用的动态链接器/system/bin/linker，而不是通常所用的ld.so。
Android编译环
境供给了”showcommands”选项来显示编译命令行，咱们能够通过翻开这个选项来查看一些编译时的细节。当然，在这之前要把上一篇中的helloworld模块clean:
target thumb C: helloworld <= development/hello/hello.c
#  readelf -d out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/LINKED/helloworld |grep NEEDED
out/host/linux-x86/bin/acp -fpt out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/LINKED/helloworld out/target/product/generic/symbols/system/bin/helloworld

接下来应用showcommands选项从新编译helloworld:

prebuilt/linux-x86/toolchain/arm-eabi-4.2.1/bin/arm-eabi-g++ -nostdlib -Bdynamic -Wl,-T,build/core/armelf.x -Wl,-dynamic-linker,/system/bin/linker -Wl,--gc-sections -Wl,-z,nocopyreloc -o out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/LINKED/helloworld -Lout/target/product/generic/obj/lib -Wl,-rpath-link=out/target/product/generic/obj/lib -lc -lstdc++ -lm  out/target/product/generic/obj/lib/crtbegin_dynamic.o         out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/hello.o       -Wl,--no-undefined prebuilt/linux-x86/toolchain/arm-eabi-4.2.1/bin/../lib/gcc/arm-eabi/4.2.1/interwork/libgcc.a out/target/product/generic/obj/lib/crtend_android.o
0x00000001 (NEEDED)                     Shared library: [libc.so]
# make helloworld showcommands
target Executable: helloworld (out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/LINKED/helloworld)
prebuilt/linux-x86/toolchain/arm-eabi-4.2.1/bin/arm-eabi-gcc  -I system/core/include   -I hardware/libhardware/include   -I hardware/ril/include   -I dalvik/libnativehelper/include   -I frameworks/base/include   -I external/skia/include   -I out/target/product/generic/obj/include   -I bionic/libc/arch-arm/include   -I bionic/libc/include   -I bionic/libstdc++/include   -I bionic/libc/kernel/common   -I bionic/libc/kernel/arch-arm   -I bionic/libm/include   -I bionic/libm/include/arch/arm   -I bionic/libthread_db/include   -I development/hello   -I out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates  -c  -fno-exceptions -Wno-multichar -march=armv5te -mtune=xscale -msoft-float -fpic -mthumb-interwork -ffunction-sections -funwind-tables -fstack-protector -D__ARM_ARCH_5__ -D__ARM_ARCH_5T__ -D__ARM_ARCH_5E__ -D__ARM_ARCH_5TE__ -include system/core/include/arch/linux-arm/AndroidConfig.h -DANDROID -fmessage-length=0 -W -Wall -Wno-unused -DSK_RELEASE -DNDEBUG -O2 -g -Wstrict-aliasing=2 -finline-functions -fno-inline-functions-called-once -fgcse-after-reload -frerun-cse-after-loop -frename-registers -DNDEBUG -UDEBUG -mthumb -Os -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64      -MD -o out/target/product/generic/obj/EXECUTABLES/helloworld_intermediates/hello.o development/hello/hello.c
再用gcc编译，生成目的文件：
从上面的命令行可以看到，Android编译环
境所用的穿插编译工具链是prebuilt/linux-x86/toolchain/arm-eabi-4.2.1/bin/arm-eabi-gcc，-I和-L参数指定了所用的C库头文件和动态库文件门路分辨是bionic/libc/include 和out/target/product/generic/obj/lib，其他还包含良多编译选项以及-D所定义的预编译宏。