英文:
What flags are needed in arm-none-eabi-gcc to produce FDPIC ELF binary?
问题
如何添加以下标志：
arm-none-eabi-gcc test.c -o test -mcpu=cortex-m4 -Wall -Os
以获取FDPIC二进制文件？
我进行了许多实验，仍然收到无效格式的消息。我知道有关链接器标志的存在：
--oformat elf32-littlearm-fdpic
但我不知道如何正确传递它们。
将编译和链接拆分为两个步骤：
arm-none-eabi-gcc -c test.c -o test.o -mcpu=cortex-m4 -Wall -Os
arm-none-eabi-ld test.o --oformat elf32-littlearm-fdpic -pie -o test
结果是没有添加新库并产生了关于启动的警告：
arm-none-eabi-ld: warning: cannot find entry symbol _start; defaulting to 0000000000000074
**谁能帮助我？什么是正确的命令（标志）？**
**我想在“裸机”Linux内核上启动我的程序（我已经在那个STM32上编译了工作内核）。我将它交付在内核中编译的initramfs中**
编辑：
arm-none-eabi-gcc test.c -o test -mcpu=cortex-m4 -Wall -fpic -fpie -Os -Xlinker "--oformat elf32-littlearm-fdpic"
结果：
/usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: unrecognized option '--oformat elf32-littlearm-fdpic'
/usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: use the --help option for usage information
collect2: error: ld returned 1 exit status
make: *** [Makefile:5: all] Error 1
-----------------------------------------------------------------
**此外，这似乎有效（但我想使用启动文件）：**
Makefile：
all:
arm-none-eabi-as -mcpu=cortex-m4 init.S -o init.o
arm-none-eabi-gcc -c -fpic -Os -mcpu=cortex-m4 -fpie -Wall init.c -o init-c.o
arm-none-eabi-ld init.o init-c.o --oformat elf32-littlearm-fdpic -pie -o init --thumb-entry=_start
init.c：
#define USART1_DR (*((volatile unsigned int *)0x40011004))
int main()
{
volatile int i;
USART1_DR = 'A';
for (i = 0; i < 1000000; i++) {
}
USART1_DR = 'B';
while (1) {}
return 0;
}
init.S：
.syntax unified
.cpu cortex-m4
.thumb
.global _start
_start:
bl main
b .
注意：以上内容是您提供的信息的翻译，不包括代码部分。如果您需要进一步的帮助或解释，请随时提出。
英文:
what flags do i need to add to:
arm-none-eabi-gcc test.c -o test -mcpu=cortex-m4 -Wall -Os
to get FDPIC binary ?
I made many experiments, and still i receive not a valid format. I know about existence of linker flags:
--oformat elf32-littlearm-fdpic
but i don't know how to pass them properly.
Spliting compiling and linking into separate steps:
arm-none-eabi-gcc -c test.c -o test.o -mcpu=cortex-m4 -Wall -Os
arm-none-eabi-ld test.o --oformat elf32-littlearm-fdpic -pie -o test
Result in that no newlib is added and warning about start is produced:
arm-none-eabi-ld: warning: cannot find entry symbol _start; defaulting to 0000000000000074
Who can help me ? What is the correct commands (flags) ?
I want to start my program on "bare" linux kernel (i have already working kernel on that stm32). I deliver it in initramfs compiled in kernel
EDIT:
arm-none-eabi-gcc test.c -o test -mcpu=cortex-m4 -Wall -fpic -fpie -Os -Xlinker "--oformat elf32-littlearm-fdpic"
Results:
/usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: unrecognized option '--oformat elf32-littlearm-fdpic'
/usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: use the --help option for usage information
collect2: error: ld returned 1 exit status
make: *** [Makefile:5: all] Error 1
MOREOVER this tends to work (but i want to use start files):
Makefile:
all:
arm-none-eabi-as -mcpu=cortex-m4 init.S -o init.o
arm-none-eabi-gcc -c -fpic -Os -mcpu=cortex-m4 -fpie -Wall init.c -o init-c.o
arm-none-eabi-ld init.o init-c.o --oformat elf32-littlearm-fdpic -pie -o init --thumb-entry=_start
init.c:
#define USART1_DR (*((volatile unsigned int *)0x40011004))
int main()
{
volatile int i;
USART1_DR = 'A';
for (i = 0; i < 1000000; i++) {
}
USART1_DR = 'B';
while (1) {}
return 0;
}
init.S:
.syntax unified
.cpu cortex-m4
.thumb
.global _start
_start:
bl main
b .
I mean compilation commands. I know my code snippet works only because STM32 has no MMU (and i configured kernel not to use MPU).
答案1
得分: 1
arm-none-eabi-gcc 用于构建在裸机环境中运行的东西，没有涉及操作系统。从快速搜索来看，FDPIC 似乎是用于在没有 MMU 的平台上加载共享库的 ABI。
如果我没有弄错，你不能在裸机环境中加载共享库，因此问题可能是你正在使用错误的编译器构建？
英文:
arm-none-eabi-gcc is for building things that run on bare-metal, with no OS involved. From a quick search FDPIC seems to be an ABI for loading shared libraries in platforms with no MMU.
If I'm not mistaken, you can't load shared libraries in bare-metal environments, thus maybe the problem is that you're building with the wrong compiler?
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