More GCC Communication Time Problems: undefined home page link

Question

I am writing software for a Cortex-A8 processor, and I need to write some ARM assembly code to access specific registers. I use gnu compilers and their associated tool chains, these tools are installed on the processor board (Freescale i.MX515) with Ubuntu. I connect to it from my PC (Windows) using WinSCP and PuTTY terminal.

As usual, I started with a simple C project with main.c and functions.s . I compile main.c using GCC , compile functions. Using the generated object files as well as the link , GCC is used again, but strange errors occur during this process.

The important conclusion is

Meanwhile, I found out that my build code may have some problems, because when I individually build it with the as -o functions.o functions.s command and try to run the generated .o function with the ./functions.o , the bash shell cannot recognize this file as an executable file (when you click on the functions.o tab, it does not receive selection / PuTTY does not select the file).

Can anyone suggest what is going on here? Are there any specific parameters that I have to send to GCC during the binding process? The errors that I see are strange and not in my understanding, I do not understand what GCC refers to.

I insert the contents of main.c, functions.s, Makefile and a list of errors here.

Help me please!!!

Recent bugs are included after the makfile has been edited as suggested by the guys here -

 ubuntu@ubuntu-desktop :~/Documents/Project/Others/helloworld$ make gcc -c -mcpu=cortex-a8 main.c as -mcpu=cortex-a8 -o functions.o functions.s gcc -o hello main.o functions.o functions.o: In function `_start': (.text+0x0): multiple definition of `_start' /usr/lib/gcc/arm-linux-gnueabi/4.3.3/../../../crt1.o:init.c:(.text+0x0): first defined here collect2: ld returned 1 exit status make: *** [hello] Error 1 

---

main.c

 #include <stdio.h> #include <stdlib.h> int main(void) { puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */ return EXIT_SUCCESS; } 

functions.s

 * Main program */ .equ STACK_TOP, 0x20000800 .text .global _start .syntax unified _start: .word STACK_TOP, start .type start, function start: movs r0, #10 movs r1, #0 .end 

Makefile

 all: hello hello: main.o functions.o gcc hello -o main.o functions.o 

- hi was included here after the guys suggest on stackoverflow, but the problem still persists, I still get the same errors.

 main.o: main.c gcc -c -mcpu=cortex-a8 main.c functions.o: functions.s as -mcpu=cortex-a8 -o functions.o functions.s 

Mistakes

 ubuntu@ubuntu-desktop :~/Documents/Project/Others/helloworld$ make gcc -c -mcpu=cortex-a8 main.c as -mcpu=cortex-a8 -o functions.o functions.s gcc -o main.o functions.o functions.o: In function `_start': (.text+0x0): multiple definition of `_start' /usr/lib/gcc/arm-linux-gnueabi/4.3.3/../../../crt1.o:init.c:(.text+0x0): first defined here /usr/lib/gcc/arm-linux-gnueabi/4.3.3/../../../crt1.o: In function `_start': init.c:(.text+0x30): undefined reference to `main' collect2: ld returned 1 exit status make: *** [hello] Error 1 

Answer 1

In the make file:

 hello: main.o functions.o gcc -o main.o functions.o 

it should be:

 hello: main.o functions.o gcc -o hello main.o functions.o 

As with you, you bundle functions.o, but not main.o, and create an executable output file called main.o that overwrites the existing main.o.

Answer 2

Not worth it

 hello: main.o functions.o gcc -o main.o functions.o 

will be

 hello: main.o functions.o gcc -o hello main.o functions.o 

Answer 3

As Bigbohne suggests, gcc is trying to link a standard runtime library. Try adding the -nostdlib option to the gcc call:

 gcc -nostdlib -o hello main.o functions.o 

Answer 4

I think this has something to do with the Runtime library that gcc bundles at the end.

And in this library there is already "_start".

I think you need to compile without the "std library". but you will not have printf, getchar and all other useful things.