交叉编译mips：链接器错误：找不到条目符号__start；

Question

So Im trying to cross compile simple program written in assembly (using MARS) to mips executable.

# Purpose: First program, Hello World
.text            # Define the program instructions.
main:            # Label to define the main program.
li $v0,4          #Load 4into $v0 to indicate a print string.
la $a0, greeting #Load the address of the greeting into $a0.
syscall          #Print greeting.  The print is indicated by
                 # $v0 having a value of 4, and the string to    
                 # print is stored at the address in $a0. 
li $v0,10         #Load a 10 (halt) into $v0.
syscall          # The program ends.
.data            # Define the program data.
greeting: .asciiz "Hello World" #The string to print.

first I use

mips-linux-as ./HelloWorld.asm -o HelloWorld.o

then

mips-linux-ld HelloWorld.o -o HelloWorld

and I get an error

mips-linux-xld: warning: cannot find entry symbol __start; defaulting to 00000000004000b0

Simply adding _start section does not work I get same error.So I written simple program in C (HelloWorld.c) and generated assembly using gcc with following command

mips-linux-gcc -O2 -S -c HelloWorld.c

and there is no _start section

    .file   1 "HelloWorld.c"
    .section .mdebug.abi32
    .previous
    .gnu_attribute 4, 3
    .abicalls
    .section    .rodata.str1.4,"aMS",@progbits,1
    .align  2
$LC0:
    .ascii  "Hello Worldn\000"
    .text
    .align  2
    .globl  main
    .set    nomips16
    .ent    main
    .type   main, @function
main:
    .frame  $sp,32,$31      # vars= 0, regs= 1/0, args= 16, gp= 8
    .mask   0x80000000,-4
    .fmask  0x00000000,0
    .set    noreorder
    .set    nomacro

    addiu   $sp,$sp,-32
    sw  $31,28($sp)
    lui $28,%hi(__gnu_local_gp)
    addiu   $28,$28,%lo(__gnu_local_gp)
    .cprestore  16
    lui $4,%hi($LC0)
    lw  $25,%call16(printf)($28)
    jalr    $25
    addiu   $4,$4,%lo($LC0)

    move    $2,$0
    lw  $31,28($sp)
    j   $31
    addiu   $sp,$sp,32

    .set    macro
    .set    reorder
    .end    main
    .size   main, .-main
    .ident  "GCC: (GNU) 4.4.5-1.5.5p4"

So what Im missing ? I would like to run this program on my mips box.

Answer 1

Try adding this to your asm file

.globl  main
.ent    main
.type   main, @function

However, you will need to use MIPS Linux syscalls , and not MARS syscalls.