linker - 使用 arm-none-eabi-gcc 编译器为 RaspberryPI2 和 BeableBoneBlack 编译 sqrt 函数时出错
问题描述
我是这种编码的新手，我正在尝试为 Cortex-A 处理器执行一些测试执行裸机软件。我有使用 Cortex-M MCU 的经验，我使用 ARM-Keil 之类的 IDE 和 Nordic 的 SDK 编译了一些 BLE 作业的代码。现在我想尝试更好地了解 Cortex-A 的世界，我将从我在网上找到的一些示例开始以裸机方式学习编码。我有一些使用 Cortex-M 的 freeRTOS 的经验，所以我在网上找到了一些好人的 git 存储库，它为 RaspberryPI 和 BeableBoneBlack 移植了 freeRTOS。从现在开始，我将只为 BeableBoneBlack 解释我的问题，因为对于 RaspberryPI，它是相似的。
我在 linux 上，我安装了 gcc-arm-none-eabi 编译器，所以我从这个链接克隆了带有 freeRTOS 存储库的 BeagleBone Black 。
我通常使用 VS Code 来编写代码，所以在集成终端中，当我运行命令时，它会正常工作，并且我的 BBB 会正确闪烁。所以现在我想改进我的代码，为了做一些测试，我想使用stdlib.hrand()中的函数。不幸的是，我发现有一些错误：. 最近几个月，在使用 BBB 进行测试之前，我找到了 RPi2 的其他存储库，并且我了解了有关 arm-none-eabi 编译器的链接器的一些信息，这需要在此过程中添加一些参数以按顺序链接库文件。从这个 repo 现在我有两个文件： makedefs_ti和makefile。打开我在第 26-27 行找到的生成文件的部分文件undefined reference to randapp，所以在哪里调用链接器。在这一行中有对LIB_GCCand的引用LIB_C，它们在makedefs_ti中定义。在第 49-50 行中，引用了安装编译器的目录（我更改了 4.7.3，在我的 linux pc 上安装了正确的 9.2.1）。在 makefile 之后-L$(LIB_C)，如果我添加链接器参数，如-lcor-lg并尝试重新编译，我有错误，如arm-none-eabi-ld: cannot find -lc. 通过对在线资源的一些了解，我修改了makedefs_ti如下：
# Toolchain/library path. LIB_PATH is an exported environmental variable which
# shall point to the installation of toolchain
#
#LIB_GCC=${LIB_PATH}/lib/gcc/arm-none-eabi/4.7.3/
#LIB_C=${LIB_PATH}/arm-none-eabi/lib/
LIB_GCC= /usr/lib/gcc/arm-none-eabi/9.2.1
LIB_C= /usr/lib/arm-none-eabi/lib
和makefile：
$(LD) -o $@.out $< -T bbb.ld -Map bbb.map $(APP_LIB) $(LDFLAGS) $(RUNTIMELIB) -L $(LPATH) \
-L $(LIB_GCC) -lgcc -L $(LIB_C) -lc -lg
这样，我调用rand()函数的 main.c 文件就可以正确编译。在另一个测试中，我尝试编译另一个代码。现在我编写了一对 .c 和 .h 文件（我将它们放在 rtos 目录中以利用那里存在的相同 makefile），它们在一个调用sqrt(). 因此，在编译中调用该函数main()，即使我在任何地方都包含<math.h>我有错误：
undefined reference to `sqrt'
显然编译停止了。从这里开始我尝试向链接器添加另一个参数，所以我修改了makefile如下：
$(LD) -o $@.out $< -T bbb.ld -Map bbb.map $(APP_LIB) $(LDFLAGS) $(RUNTIMELIB) -L $(LPATH) \
-L $(LIB_GCC) -lgcc -L $(LIB_C) -lc -lg -lm
我得到了其他我无法以任何方式解决的错误：
arm-none-eabi-ld: /usr/lib/arm-none-eabi/lib/libm.a(lib_a-w_sqrt.o): in function `sqrt':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/math/../../../../../newlib/libm/math/w_sqrt.c:62: undefined reference to `__aeabi_dcmpun'
arm-none-eabi-ld: /build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/math/../../../../../newlib/libm/math/w_sqrt.c:63: undefined reference to `__aeabi_dcmplt'
arm-none-eabi-ld: /build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/math/../../../../../newlib/libm/math/w_sqrt.c:64: undefined reference to `__errno'
arm-none-eabi-ld: /build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/math/../../../../../newlib/libm/math/w_sqrt.c:65: undefined reference to `__aeabi_ddiv'
arm-none-eabi-ld: /usr/lib/arm-none-eabi/lib/libm.a(lib_a-e_sqrt.o): in function `__ieee754_sqrt':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/machine/arm/../../../../../../newlib/libm/machine/arm/../../math/e_sqrt.c:110: undefined reference to `__aeabi_dmul'
arm-none-eabi-ld: /build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/machine/arm/../../../../../../newlib/libm/machine/arm/../../math/e_sqrt.c:110: undefined reference to `__aeabi_dadd'
arm-none-eabi-ld: /build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/machine/arm/../../../../../../newlib/libm/machine/arm/../../math/e_sqrt.c:117: undefined reference to `__aeabi_dsub'
arm-none-eabi-ld: /build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libm/machine/arm/../../../../../../newlib/libm/machine/arm/../../math/e_sqrt.c:117: undefined reference to `__aeabi_ddiv'
make: *** [makefile:26: app] Errore 1
我会说，sqrt()在 main 中调用正常工作，当我sqrt()在其他 .c 文件中调用时会出现问题。相反，rand().c 附加文件中的函数可以正常工作。
我不知道如何解决这些错误，有人可以帮助我吗？
我另一天尝试的是在 Code Composer Studio 项目中编写相同的代码并且它可以工作（具有在附加 .c 文件中调用 sqrt 和 rand 的相同函数。有什么区别？
如果这是一个很长的解释，我很抱歉，但我没有找到另一种方式来解释我的情况。
提前非常感谢。
齐射
解决方案
开始.s
.globl _start
_start:
;@ enable fpu
mrc p15, 0, r0, c1, c0, 2
orr r0,r0,#0x300000 ;@ single precision
orr r0,r0,#0xC00000 ;@ double precision
mcr p15, 0, r0, c1, c0, 2
mov r0,#0x40000000
fmxr fpexc,r0
mov sp,#0x8000
bl notmain
hang: b hang
不是main.c
double notmain ( double a, double b )
{
return(a+b);
}
（不是真正的裸机应用程序，源自一个）
为硬浮动而构建
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -mhard-float -mfpu=vfp -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf
arm-none-eabi-objdump -D notmain.elf > notmain.list
arm-none-eabi-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
arm-none-eabi-objcopy notmain.elf -O binary kernel.img
使用的硬件浮点数
00008024 <notmain>:
8024: ee300b01 vadd.f64 d0, d0, d1
8028: e12fff1e bx lr
构建软浮动
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf
arm-none-eabi-ld: notmain.o: in function `notmain':
notmain.c:(.text+0x4): undefined reference to `__aeabi_dadd'
Makefile:33: recipe for target 'notmain.elf' failed
make: *** [notmain.elf] Error 1
它需要 gcclib。
使用 gcc 作为链接器（我知道这是多么可怕的想法）。
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -c notmain.c -o notmain.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf -lgcc
arm-none-eabi-objdump -D notmain.elf > notmain.list
arm-none-eabi-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
arm-none-eabi-objcopy notmain.elf -O binary kernel.img
...
00008024 <notmain>:
8024: e92d4010 push {r4, lr}
8028: eb000003 bl 803c <__adddf3>
802c: e8bd8010 pop {r4, pc}
00008030 <__aeabi_drsub>:
8030: e2211102 eor r1, r1, #-2147483648 ; 0x80000000
8034: ea000000 b 803c <__adddf3>
00008038 <__aeabi_dsub>:
8038: e2233102 eor r3, r3, #-2147483648 ; 0x80000000
0000803c <__adddf3>:
803c: e92d4030 push {r4, r5, lr}
gcc 正在将这些传递给 ld。
[0][/opt/gnuarm/lib/gcc/arm-none-eabi/10.2.0/../../../../arm-none-eabi/bin/ld]
[1][-plugin]
[2][/opt/gnuarm/libexec/gcc/arm-none-eabi/10.2.0/liblto_plugin.so]
[3][-plugin-opt=/opt/gnuarm/libexec/gcc/arm-none-eabi/10.2.0/lto-wrapper]
[4][-plugin-opt=-fresolution=/tmp/ccRiWZtk.res]
[5][-X]
[6][-o]
[7][notmain.elf]
[8][-L/opt/gnuarm/lib/gcc/arm-none-eabi/10.2.0]
[9][-L/opt/gnuarm/lib/gcc/arm-none-eabi/10.2.0/../../../../arm-none-eabi/lib]
[10][start.o]
[11][notmain.o]
[12][-lgcc]
[13][-T]
[14][memmap]
find | grep libgcc
./lib/gcc/arm-none-eabi/10.2.0/libgcc.a
./lib/gcc/arm-none-eabi/10.2.0/thumb/libgcc.a
./lib/gcc/arm-none-eabi/10.2.0/thumb/autofp/v7/fpu/libgcc.a
./lib/gcc/arm-none-eabi/10.2.0/arm/autofp/v5te/fpu/libgcc.a
所以使用 ld 然后
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf -L/opt/gnuarm/lib/gcc/arm-none-eabi/10.2.0/ -lgcc
arm-none-eabi-objdump -D notmain.elf > notmain.list
arm-none-eabi-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
arm-none-eabi-objcopy notmain.elf -O binary kernel.img
为什么它现在使用 addf3 ？不知道。
00008024 <notmain>:
8024: e92d4010 push {r4, lr}
8028: eb000003 bl 803c <__adddf3>
802c: e8bd8010 pop {r4, pc}
00008030 <__aeabi_drsub>:
8030: e2211102 eor r1, r1, #-2147483648 ; 0x80000000
8034: ea000000 b 803c <__adddf3>
00008038 <__aeabi_dsub>:
8038: e2233102 eor r3, r3, #-2147483648 ; 0x80000000
0000803c <__adddf3>:
803c: e92d4030 push {r4, r5, lr}
8040: e1a04081 lsl r4, r1, #1
8044: e1a05083 lsl r5, r3, #1
这就是你处理 aeabi 东西的方式，你需要使用硬浮点或包含 gcclib 的路径，或者只是将它添加到行中
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf /opt/gnuarm/lib/gcc/arm-none-eabi/10.2.0/libgcc.a
#arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf -lgcc
arm-none-eabi-objdump -D notmain.elf > notmain.list
arm-none-eabi-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
arm-none-eabi-objcopy notmain.elf -O binary kernel.img
现在 sqrt() 是 C 库的东西而不是 gcc 库的东西所以你需要一个 C 库（看起来你正在尝试使用 newlib）并且你需要构建 C 库以匹配 gcc 所以你需要构建它或者软浮动，需要包含正确的库。我没有……嗯……
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf /home/so/gcc-arm-none-eabi-9-2019-q4-major/lib/gcc/arm-none-eabi/9.2.1/libgcc.a
arm-none-eabi-objdump -D notmain.elf > notmain.list
arm-none-eabi-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
arm-none-eabi-objcopy notmain.elf -O binary kernel.img
所以
double sqrt(double x);
double notmain ( double a )
{
return(sqrt(a));
}
看起来很熟悉
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf /home/so/gcc-arm-none-eabi-9-2019-q4-major/lib/gcc/arm-none-eabi/9.2.1/libgcc.a /home/so/gcc-arm-none-eabi-9-2019-q4-major/arm-none-eabi/lib/libm.a
arm-none-eabi-ld: /home/so/gcc-arm-none-eabi-9-2019-q4-major/arm-none-eabi/lib/libm.a(lib_a-w_sqrt.o): in function `sqrt':
w_sqrt.c:(.text.sqrt+0x34): undefined reference to `__aeabi_dcmpun'
arm-none-eabi-ld: w_sqrt.c:(.text.sqrt+0x6c): undefined reference to `__aeabi_dcmplt'
arm-none-eabi-ld: w_sqrt.c:(.text.sqrt+0xc4): undefined reference to `__aeabi_ddiv'
arm-none-eabi-ld: w_sqrt.c:(.text.sqrt+0xd8): undefined reference to `__errno'
arm-none-eabi-ld: w_sqrt.c:(.text.sqrt+0x120): undefined reference to `__errno'
arm-none-eabi-ld: /home/so/gcc-arm-none-eabi-9-2019-q4-major/arm-none-eabi/lib/libm.a(lib_a-e_sqrt.o): in function `__ieee754_sqrt':
e_sqrt.c:(.text.__ieee754_sqrt+0x200): undefined reference to `__aeabi_dmul'
arm-none-eabi-ld: e_sqrt.c:(.text.__ieee754_sqrt+0x20c): undefined reference to `__aeabi_dadd'
arm-none-eabi-ld: e_sqrt.c:(.text.__ieee754_sqrt+0x22c): undefined reference to `__aeabi_dsub'
arm-none-eabi-ld: e_sqrt.c:(.text.__ieee754_sqrt+0x238): undefined reference to `__aeabi_ddiv'
Makefile:33: recipe for target 'notmain.elf' failed
make: *** [notmain.elf] Error 1
寻找
./arm-none-eabi/lib/libm.a
./arm-none-eabi/lib/thumb/v7e-m/nofp/libm.a
./arm-none-eabi/lib/thumb/v6-m/nofp/libm.a
./arm-none-eabi/lib/thumb/v8-m.base/nofp/libm.a
./arm-none-eabi/lib/thumb/v7/nofp/libm.a
./arm-none-eabi/lib/thumb/v8-m.main+dp/hard/libm.a
./arm-none-eabi/lib/thumb/v8-m.main+dp/softfp/libm.a
./arm-none-eabi/lib/thumb/v7e-m+dp/hard/libm.a
./arm-none-eabi/lib/thumb/v7e-m+dp/softfp/libm.a
./arm-none-eabi/lib/thumb/v7-r+fp.sp/hard/libm.a
./arm-none-eabi/lib/thumb/v7-r+fp.sp/softfp/libm.a
./arm-none-eabi/lib/thumb/v7e-m+fp/hard/libm.a
./arm-none-eabi/lib/thumb/v7e-m+fp/softfp/libm.a
./arm-none-eabi/lib/thumb/v8-m.main+fp/hard/libm.a
./arm-none-eabi/lib/thumb/v8-m.main+fp/softfp/libm.a
./arm-none-eabi/lib/thumb/v7-m/nofp/libm.a
./arm-none-eabi/lib/thumb/nofp/libm.a
./arm-none-eabi/lib/thumb/v7+fp/hard/libm.a
./arm-none-eabi/lib/thumb/v7+fp/softfp/libm.a
./arm-none-eabi/lib/thumb/v8-m.main/nofp/libm.a
./arm-none-eabi/lib/arm/v5te/hard/libm.a
./arm-none-eabi/lib/arm/v5te/softfp/libm.a
armv5te 应该适用于 armv6
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf /home/so/gcc-arm-none-eabi-9-2019-q4-major/lib/gcc/arm-none-eabi/9.2.1/libgcc.a /home/so/gcc-arm-none-eabi-9-2019-q4-major/arm-none-eabi/lib/arm/v5te/softfp/libm.a
arm-none-eabi-ld: /home/so/gcc-arm-none-eabi-9-2019-q4-major/arm-none-eabi/lib/arm/v5te/softfp/libm.a(lib_a-w_sqrt.o): in function `sqrt':
w_sqrt.c:(.text.sqrt+0x94): undefined reference to `__errno'
arm-none-eabi-ld: w_sqrt.c:(.text.sqrt+0xdc): undefined reference to `__errno'
Makefile:33: recipe for target 'notmain.elf' failed
make: *** [notmain.elf] Error 1
errno 是一个全局变量。C 库可能想要用于软浮点。
int __errno;
double sqrt(double x);
double notmain ( double a )
{
return(sqrt(a));
}
现在工具很开心
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf /home/so/gcc-arm-none-eabi-9-2019-q4-major/lib/gcc/arm-none-eabi/9.2.1/libgcc.a /home/so/gcc-arm-none-eabi-9-2019-q4-major/arm-none-eabi/lib/arm/v5te/softfp/libm.a
arm-none-eabi-objdump -D notmain.elf > notmain.list
arm-none-eabi-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
arm-none-eabi-objcopy notmain.elf -O binary kernel.img
但这是硬浮不软。
00008024 <notmain>:
8024: eaffffff b 8028 <sqrt>
00008028 <sqrt>:
8028: e52de004 push {lr} ; (str lr, [sp, #-4]!)
802c: ed2d8b02 vpush {d8}
8030: e1a02000 mov r2, r0
8034: e1a03001 mov r3, r1
8038: e24dd02c sub sp, sp, #44 ; 0x2c
803c: ec432b18 vmov d8, r2, r3
8040: eb000038 bl 8128 <__ieee754_sqrt>
8044: e59f30d4 ldr r3, [pc, #212] ; 8120 <sqrt+0xf8>
8048: eeb48b48 vcmp.f64 d8, d8
804c: e1d3c0d0 ldrsb ip, [r3]
8050: eef1fa10 vmrs APSR_nzcv, fpscr
你知道解决这个问题的途径是什么。您需要一个正确匹配/构建的库，然后您需要链接它。Keil 和其他人只是在工具链中为你做这件事，根据项目匹配事物。和/或与工具链集成的 C 库。
建造硬浮动
arm-none-eabi-as --warn --fatal-warnings -mcpu=arm1176jzf-s -march=armv6 -mfpu=vfp start.s -o start.o
arm-none-eabi-gcc -Wall -O2 -ffreestanding -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -mhard-float -mfpu=vfp -c notmain.c -o notmain.o
arm-none-eabi-ld -nostdlib -nostartfiles start.o notmain.o -T memmap -o notmain.elf /home/so/gcc-arm-none-eabi-9-2019-q4-major/lib/gcc/arm-none-eabi/9.2.1/libgcc.a /home/so/gcc-arm-none-eabi-9-2019-q4-major/arm-none-eabi/lib/arm/v5te/hard/libm.a
arm-none-eabi-objdump -D notmain.elf > notmain.list
arm-none-eabi-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
arm-none-eabi-objcopy notmain.elf -O binary kernel.img
工具很开心。
00008024 <notmain>:
8024: eaffffff b 8028 <sqrt>
00008028 <sqrt>:
8028: e52de004 push {lr} ; (str lr, [sp, #-4]!)
802c: ed2d8b02 vpush {d8}
8030: eeb08b40 vmov.f64 d8, d0
8034: e24dd02c sub sp, sp, #44 ; 0x2c
8038: eb000038 bl 8120 <__ieee754_sqrt>
803c: eeb48b48 vcmp.f64 d8, d8
8040: e59f30d0 ldr r3, [pc, #208] ; 8118 <sqrt+0xf0>
8044: e1d310d0 ldrsb
必须使它成为一个真正的应用程序 main 调用另一个函数，其中调用了 sqrt 。然后在硬件上运行它和/或检查这些指令。或者甚至更好地获取 sqrt 的 C 库实现并在项目中构建它，以便它匹配目标和指令集。（根据需要与 libgcc 调用相同，测试它们或构建它们）。
推荐阅读
- javascript - 在 Angular 中访问当前 DOM 节点的子节点
- winapi - winAPI GetAdaptersAddresses 不可打印的友好名称
- python - 如何使用外部文件存在/内容控制 python 程序行为？
- javascript - React Native TouchableOpacity 不适用于绝对位置
- gatsby - 纱线：在 gatsby 部署到 netlify 后找不到命令
- c++ - win32/C++ 在资源中嵌入文本文件
- c# - 如何将 WPF 中的自动设置参数与 MVVM 绑定
- c++ - 使用“friend”关键字重载 C++ 运算符
- angular - 如何在 Angular 9 中使用 observable 限制 API 请求
- css - 在没有溢出隐藏的情况下禁用IOS上的水平滚动和弹跳