Writing and Compiling Program For OpenWrt

问题

I have a embedded device with MIPS arch working under OpenWRT

system type: MediaTek MT7628AN ver:1 eco:2
machine: WRTnode2P processor: 0
cpu model: MIPS 24KEc V5.5

I want to compile compile a small program in C through my computer (ubuntu)

#include <stdio.h>

int main(void){
    printf("HelloWorld");
    return 0;
}

To compile it I use mips-linux-gnu-gcc command

mips-linux-gnu-gcc -march=24kec -mabi=32 hello.c -o hello

I send hello program to my device and make a chmod 755

chmod 755 hello

When I try to execute it I have an error

root@openWrt:/www# ./hello
./hello: line 1: syntax error: unexpected word (expecting ")")

I don't understand what's going on, I tried some others command to compile it like with argument: -EB or -EL or not, -static or not, -mabi=32 and not, but I have same problem.

Anyone to help me?

Thanks

[UPDATE]

I send a file command to existing file and this is result

fw3: ELF 32-bit LSB executable, MIPS, MIPS32 rel2 version 1, dynamically linked, interpreter /lib/ld., for GNU/Linux 3.2.0, stripped

so I compile my program with this command

mipsel-linux-gnu-gcc -march=24kec -mips32r2  -mips16   hello.c -o hello

now I have this file command result

hello: ELF 32-bit LSB executable, MIPS, MIPS32 rel2 version 1 (SYSV), dynamically linked, interpreter /lib/ld., for GNU/Linux 3.2.0, BuildID[sha1]=cd12319441c530606d52d96478719b06a7b215a7, not stripped

Now I read ELF of my remote program

ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 01 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       1
  Type:                              EXEC (Executable file)
  Machine:                           MIPS R3000
  Version:                           0x1
  Entry point address:               0x402c40
  Start of program headers:          52 (bytes into file)
  Start of section headers:          78592 (bytes into file)
  Flags:                             0x74001005, noreorder, cpic, o32, mips16, mips32r2
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         10
  Size of section headers:           40 (bytes)
  Number of section headers:         31
  Section header string table index: 30

and this my hello program readelf command

ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           MIPS R3000
  Version:                           0x1
  Entry point address:               0x4005c0
  Start of program headers:          52 (bytes into file)
  Start of section headers:          6700 (bytes into file)
  Flags:                             0x74001007, noreorder, pic, cpic, o32, mips16, mips32r2
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         11
  Size of section headers:           40 (bytes)
  Number of section headers:         33
  Section header string table index: 30

There is two difference ABI version and in flags there is pic

If I try to launch my hello program I have this error

hello: error while loading shared libraries: libc.so.6: cannot open shared object file: No such file or directory

I try to add -static argument but I have this error when I launch my hello program

Illegal instruction

I'm always stuck with this problem.

回答1:

I have a similar issue and fixed it by setting architect to mipsle. I'm using Go to build binary for linux/mips on this device,

system type     : MediaTek MT7620A ver:2 eco:6
cpu model       : MIPS 24KEc V5.0
isa             : mips1 mips2 mips32r1 mips32r2
ASEs implemented    : mips16 dsp

It fails on the first time,

macbook:# cat main.go
package main

import (
    "fmt"
)

func main() {
    fmt.Println("hello, mips")
}

############# Setting GOARCH=mips ============

macbook:# GOOS=linux GOARCH=mips GOMIPS=softfloat go build -o hello-mips

openwrt:# ./hello-mips
./hello-mips: line 1: syntax error: unexpected "("

Then I realized the CPU arch is Little-Endian, not the default Big-Endian. So I changed the build parameter and it successes now.

############# Setting GOARCH=mipsle ============

macbook:# GOOS=linux GOARCH=mipsle GOMIPS=softfloat go build -o hello
openwrt:# ./hello
hello, mips

Your CPU model is same as mine and only differs in the revision MIPS 24KEc V5.5, it must also be mipsle (mipsel). Hope it helps.

来源：https://stackoverflow.com/questions/55878437/writing-and-compiling-program-for-openwrt

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embedded

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openwrt