[英]Linking multiple static libraries
首先让我说这是我第一次真正干预 GCC,所以如果这个问题不是很有建设性或以前已经回答过,我深表歉意。
我有两个 static 库:
“L1.h”
void __attribute__((weak)) Logger_Init(void) { // Invalid... }
“L2.h”
void Logger_Init(void);
“L2.c”
void Logger_Init(void)
{
// Do stuff...
}
我的目标是让某些可执行文件在编译过程中包含“L2”并覆盖“L1”的Logger_Init
实现。
我在这里读到你不能链接两个 static 库,但我会检查是否在运行时调用Logger_Init
,所以我需要在编译期间声明 function。
在可执行项目中,有一个添加库路径和名称的选项,我在其中添加了这两个库。 我的第一个问题是,这里的顺序重要吗? 我在下面使用了这两个命令,没有任何区别(它们被修剪了很多,但我认为这是相关部分)。
gcc -L(L1_PATH) -L(L2_PATH) -l(L1_NAME) -l(L2_NAME)
gcc -L(L2_PATH) -L(L1_PATH) -l(L2_NAME) -l(L1_NAME)
不过,我的主要问题是,如何告诉链接器(?)在另一个 static 库中存在对 function 的强定义,或者类似的东西?
我还读到使用__attribute__((weak))
对 static 库不是很有帮助,但我不太明白为什么,它似乎完全符合我的目标。
我可以在这里编译和运行所有内容,但是不会调用Logger_Init
的“L2”实现。
我在嵌入式环境中工作,所以使用动态/共享库是不可能的。
编辑:
根据请求,Bodo,这里是命令的完整列表。 我不是在编写这些命令,它们都是由 Vitis 自动生成的。 这是我运行我的代码的地方。 我打开详细,让它撕裂。 超过一半的东西对我来说都是胡言乱语,我为臃肿感到抱歉。 最底层是有用的东西。
make all
make --no-print-directory pre-build
a9-linaro-pre-build-step
' '
make --no-print-directory main-build
'Building file: ../src/main.c'
'Invoking: ARM v7 gcc compiler'
arm-none-eabi-gcc -Wall -O0 -g3 -c -fmessage-length=0 -MT"src/main.o"
-mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard -v -IC:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bspinclude/include
-MMD -MP -MF"src/main.d" -MT"src/main.o" -o "src/main.o" "../src/main.c"
Using built-in specs.
COLLECT_GCC=C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\x86_64-oesdk-mingw32\usr\bin\arm-xilinx-eabi\arm-xilinx-eabi-gcc.exe
Target: arm-xilinx-eabi
Configured with: ../../../../../../work-shared/gcc-9.2.0-r0/gcc-9.2.0/configure
--build=x86_64-linux --host=x86_64-oesdk-mingw32 --target=arm-xilinx-eabi --prefix=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr --exec_prefix=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr
--bindir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi
--sbindir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi
--libexecdir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/libexec/arm-xilinx-eabi
--datadir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/share
--sysconfdir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/etc --sharedstatedir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/com
--localstatedir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/var
--libdir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/lib/arm-xilinx-eabi
--includedir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/us r/include
--oldincludedir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/include
--infodir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/share/info --mandir=/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/share/man
--disable-silent-rules --disable-dependency-tracking --with-libtool-sysroot=/scratch/mhatle/baremetal-toolchains/20200708-172230/build/aarch32-tc-x86_64-mingw32/work/x86_64-nativesdk-mingw32-oesdk-mingw32/gcc-cross-canadian-arm/9.2.0-r0/recipe-sysroot
--enable-clocale=generic --with-gnu-ld --enable-shared --enable-languages=c,c++ --enable-threads=posix --enable-multilib --enable-c99 --enable-long-long --enable-libstdcxx-pch --program-prefix=arm-xilinx-eabi- --without-local-prefix --enable-lto --disable-libssp --enable-libitm --disable-bootstrap --disable-libmudflap --with-system-zlib --enable-linker-build-id --with-ppl=no --with-cloog=no --enable-checking=release --enable-cheaders=c_global --without-isl --with-gxx-include-dir=/not/exist/usr/include/c++/9.2.0 --wi th-build-time-tools=/scratch/mhatle/baremetal-toolchains/20200708-172230/build/aarch32-tc-x86_64-mingw32/work/x86_64-nativesdk-mingw32-oesdk-mingw32/gcc-cross-canadian-arm/9.2.0-r0/recipe-sysroot-native/usr/arm-xilinx-eabi/bin
--with-build-sysroot=/scratch/mhatle/baremetal-toolchains/20200708-172230/build/aarch32-tc-x86_64-mingw32/work/x86_64-nativesdk-mingw32-oesdk-mingw32/gcc-cross-canadian-arm/9.2.0-r0/recipe-sysroot
--enable-poison-system-directories --disable-nls --enable-initfini-array --without-headers --with-newlib --disable-libstdcxx-pch --with-newlib --disable-threads --enable-plugins --with-gnu-as --disable-libitm --with-multilib-list=aprofile --enable-multilib --disable-nls --enable-mingw-wildcard --with-sysroot=/not/exist
Thread model: single
gcc version 9.2.0 (GCC)
COLLECT_GCC_OPTIONS='--sysroot=C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\aarch32-xilinx-eabi' '-Wall' '-O0' '-g3' '-c' '-fmessage-length=0' '-MT' 'src/main.o' '-mcpu=cortex-a9' '-mfpu=vfpv3' '-mfloat-abi=hard' '-v' '-I' 'C:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bspinclude/include' '-MMD' '-MP' '-MF' 'src/main.d' '-MT' 'src/main.o' '-o' 'src/main.o' '-marm' '-march=armv7-a+mp+sec+vfpv3'
c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi/../../libexec/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/cc1.exe
-quiet -v -I C:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bspinclude/include
-imultilib thumb/v7-a+fp/hard -iprefix c:\xilinx\vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\x86_64-oesdk-mingw32\usr\bin\arm-xilinx-eabi\../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/
-isysroot C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\aarch32-xilinx-eabi
-MMD src/main.d -MF src/main.d -MP -MT src/main.o -MT src/main.o -dD -D__USES_INITFINI__ ../src/main.c -quiet -dumpbase main.c -mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard -marm -march=armv7-a+mp+sec+vfpv3 -auxbase-strip src/main.o -g3 -O0 -Wall -version -fmessage-length=0 -o C:\Users\M257B~1.BLA\AppData\Local\Temp\ccOuqloW.s
GNU C17 (GCC) version 9.2.0 (arm-xilinx-eabi)
compiled by GNU C version 9.2.0, GMP version 6.1.2, MPFR version
4.0.2, MPC version 1.1.0, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "c:\xilinx\vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\x86_64-oesdk-mingw32\usr\bin\arm-xilinx-eabi\../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/../../../../../arm-xilinx-eabi/include"
ignoring duplicate directory "c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/lib/arm-xilinx-eabi/gcc/../../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/include"
ignoring nonexistent directory "C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\aarch32-xilinx-eabi/usr/lib/arm-xilinx-eabi/9.2.0/include"
ignoring nonexistent directory "C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\aarch32-xilinx-eabi/usr/local/oecore-x86_64/sysroots/x86_64-oesdk-mingw32/usr/lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/../../../../include"
ignoring duplicate directory "c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/lib/arm-xilinx-eabi/gcc/../../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/include-fixed"
ignoring nonexistent directory "c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/lib/arm-xilinx-eabi/gcc/../../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/../../../../../arm-xilinx-eabi/include"
#include "..." search starts here:
#include <...> search starts here:
C:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bspinclude/include
c:\xilinx\vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\x86_64-oesdk-mingw32\usr\bin\arm-xilinx-eabi\../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/include
c:\xilinx\vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\x86_64-oesdk-mingw32\usr\bin\arm-xilinx-eabi\../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/include-fixed
C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\aarch32-xilinx-eabi/usr/include
End of search list.
GNU C17 (GCC) version 9.2.0 (arm-xilinx-eabi)
compiled by GNU C version 9.2.0, GMP version 6.1.2, MPFR version
4.0.2, MPC version 1.1.0, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 2516cb1a757555b312b0344a413e7d9c
COLLECT_GCC_OPTIONS='--sysroot=C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\aarch32-xilinx-eabi' '-Wall' '-O0' '-g3' '-c' '-fmessage-length=0' '-MT' 'src/main.o' '-mcpu=cortex-a9' '-mfpu=vfpv3' '-mfloat-abi=hard' '-v' '-I' 'C:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bspinclude/include' '-MMD' '-MP' '-MF' 'src/main.d' '-MT' 'src/main.o' '-o' 'src/main.o' '-marm' '-march=armv7-a+mp+sec+vfpv3'
c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi/../../libexec/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/as.exe
-v -I C:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bspinclude/include
-march=armv7-a+mp+sec -mfloat-abi=hard -mfpu=vfpv3 -meabi=5 -o src/main.o C:\Users\M257B~1.BLA\AppData\Local\Temp\ccOuqloW.s
GNU assembler version 2.32.0 (arm-xilinx-eabi) using BFD version (GNU Binutils) 2.32.0.20190204
COMPILER_PATH=c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi/../../libexec/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/;c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi/../../libexec/arm-xilinx-eabi/gcc/
LIBRARY_PATH=C:/Xilinx/Vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/bin//../aarch32-xilinx-eabi/usr/lib/thumb/v7-a+fp/hard/;c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi/../../lib/arm-xilinx-eabi/gcc/arm-xilinx-eabi/9.2.0/;c:/xilinx/vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/x86_64-oesdk-mingw32/usr/bin/arm-xilinx-eabi/../../lib/arm-xilinx-eabi/gcc/;C:/Xilinx/Vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/bin//../aarch32-xilinx-eabi/usr/lib/arm-xilinx-eabi/9.2.0/;C:/Xilinx/Vitis/2020.2/gnu/aarch32/nt/gcc-arm-none-eabi/bin//../aarch32-xilinx-eabi/usr/lib/
COLLECT_GCC_OPTIONS='--sysroot=C:\Xilinx\Vitis\2020.2\gnu\aarch32\nt\gcc-arm-none-eabi\bin\\..\aarch32-xilinx-eabi' '-Wall' '-O0' '-g3' '-c' '-fmessage-length=0' '-MT' 'src/main.o' '-mcpu=cortex-a9' '-mfpu=vfpv3' '-mfloat-abi=hard' '-v' '-I' 'C:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bspinclude/include' '-MMD' '-MP' '-MF' 'src/main.d' '-MT' 'src/main.o' '-o' 'src/main.o' '-marm' '-march=armv7-a+mp+sec+vfpv3'
'Finished building: ../src/main.c'
' '
'Building target: PicoZed_Main.elf'
'Invoking: ARM v7 gcc linker'
arm-none-eabi-gcc
-L"C:\Projects\Xilinx\Experiment\PicoZed\PicoZed.vitis\Library1\Debug" -L"C:\Projects\Xilinx\Experiment\PicoZed\PicoZed.vitis\Library2\Debug" -mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard -Wl,-build-id=none -specs=Xilinx.spec -Wl,-T -Wl,../src/lscript.ld -LC:/Projects/Xilinx/Experiment/PicoZed/PicoZed.vitis/PicoZed/export/PicoZed/sw/PicoZed/standalone_domain/bsplib/lib
-o "PicoZed_Main.elf" ./src/main.o -lLibrary1 -lLibrary2 -Wl,--start-group,-lxil,-lgcc,-lc,--end-group
'Finished building target: PicoZed_Main.elf'
' '
'Invoking: ARM v7 Print Size'
arm-none-eabi-size PicoZed_Main.elf |tee "PicoZed_Main.elf.size"
text data bss dec hex filename
18736 1144 22568 42448 a5d0 PicoZed_Main.elf
'Finished building: PicoZed_Main.elf.size'
' '
我的第一个问题是,这里的顺序重要吗?
是的,从字面上看来自gcc 文档:
-l 库
...
在命令中编写此选项的位置有所不同; linker按照指定的顺序搜索和处理库和 object 文件。 因此,“foo.o -lz bar.o”在文件 foo.o 之后但在 bar.o 之前搜索库“z”。 如果 bar.o 引用 'z' 中的函数,则可能不会加载这些函数。
如何告诉链接器(?)在另一个 static 库中存在对 function 的强定义,或者类似的东西?
通常在现代嵌入式中:
-Wl,--whole-archive -l(L1_NAME) -l(L2_NAME) -Wl,--no-whole-archive
另一种方法是解压缩这两个库并将 object 文件传递给 gcc。
但我不太明白为什么
Linker 搜索直到库中的第一个符号,按顺序。 所以无论你先放哪个——弱库或强库——都将使用该符号,并且将忽略所有后续相同的符号。
我可以在这里编译和运行所有内容,但是不会调用 Logger_Init 的“L2”实现。
这很奇怪,因为您帖子中的-l(L2_NAME) -l(L1_NAME)
应该会导致调用 l2 实现。 一个 MCVE:
cat >Makefile <<EOF
all: l1.a l2.a main.o
gcc main.o l1.a l2.a
./a.out
gcc main.o l2.a l1.a
./a.out
l2.a: l2.o
ar rcs $@ $<
l1.a: l1.o
ar rcs $@ $<
EOF
cat >main.c <<EOF
int main() {
void Logger_Init();
Logger_Init();
}
EOF
cat >l1.c <<EOF
void __attribute__((weak)) Logger_Init(void) {
puts("I am weak");
}
EOF
cat >l2.c <<EOF
void Logger_Init(void)
{
puts("I am strong");
}
EOF
结果是:
$ make
...
gcc main.o l1.a l2.a
./a.out
I am weak
gcc main.o l2.a l1.a
./a.out
I am strong
IE。 先到先得。 我也用-L. -ll2 -ll1
-L. -ll2 -ll1
并将库重命名为libl*.a
- 结果相同。 我怀疑你的检查方法有缺陷。
马克已经44岁了,是个留着长胡子的爷爷。 使用现代的东西,比如 cmake。
使用weak
属性可能会导致非常糟糕的意大利面条代码,以后很难修复和重构。 考虑只使用带有 get/set 访问器的 function 指针。
你能告诉我们更多关于为什么你认为弱函数不好的原因吗? @Bktero
基于意见:
缺点:
--whole-archive
来解决。 因为它依赖于顺序,所以它可能会令人惊讶,有时有效,有时无效,从而导致令人惊讶和意想不到的错误,因为您只更改库和 oops 的顺序 - 您的应用程序不起作用。 与全局变量类似的问题。 基本上与信号相同的问题。 与信号相同的解决方案 - 使用 function 指针。 就像使用SA_SIGINFO
和sigaction
一样,允许通过自定义的void *context
指针传递自定义的 function 指针。
优点:
有什么经验可以分享吗?
好吧,我使用并研究了弱(或未定义)函数作为库中的回调,它导致代码难以合并且难以重构。
STM32 HAL 库是用弱函数实现的,它们稍后可以选择启用 function 指针,现在它们的源中有一个#if (USE_HAL_*_REGISTER_CALLBACKS == 1)
东西,请参阅 ex stm32l0xx_hal_uart.h#L248
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