利用QEMU模拟大端序机器

简介

当前我们安装虚拟机，一般小端机器比较多，有时候想模拟大端机器测试程序，这时就有模拟大端机器的需求。

参考：利用 QEMU USER 模式运行 mips 程序 - sinpo828 - 博客园 (cnblogs.com)

根据这个博客的描述，可以实现大端机器的需求，其实现是模拟MIPS架构的环境。

需要使用到QEMU模拟处理器，QEMU主要有两种模拟模式：

• System Mode：它可以虚拟多种CPU架构的虚拟计算机系统，比如可以在x86 的 Ubuntu系统中虚拟出一个MIPS架构的Debian系统。
• User Mode：它可以运行为其他处理器编写的应用程序，比如可以在X64 Ubuntu系统中直接运行 MIPS Linux的应用程序。

步骤

注意：安装的虚拟机是Ubuntu系统。

1. 安装QEMU支持MIPS架构：

   $ apt install qemu-user-static qemu-system-mips
   Reading package lists... Done
   Building dependency tree
   Reading state information... Done
   qemu-system-mips is already the newest version (1:2.5+dfsg-5ubuntu10.51).
   qemu-system-mips set to manually installed.
   The following packages will be REMOVED:
     qemu-user-binfmt
   The following NEW packages will be installed:
     qemu-user-static
   0 upgraded, 1 newly installed, 1 to remove and 1 not upgraded.
   Need to get 7,592 kB of archives.
   After this operation, 85.9 MB of additional disk space will be used.
   Do you want to continue? [Y/n] y
   Get:1 http://mirrors.aliyun.com/ubuntu xenial-updates/universe amd64 qemu-user-static amd64 1:2.5+dfsg-5ubuntu10.51 [7,592 kB]
   Fetched 7,592 kB in 2s (3,777 kB/s)
   (Reading database ... 221693 files and directories currently installed.)
   Removing qemu-user-binfmt (1:2.5+dfsg-5ubuntu10.51) ...
   Selecting previously unselected package qemu-user-static.
   (Reading database ... 221693 files and directories currently installed.)
   Preparing to unpack .../qemu-user-static_1%3a2.5+dfsg-5ubuntu10.51_amd64.deb ...
   Unpacking qemu-user-static (1:2.5+dfsg-5ubuntu10.51) ...
   Processing triggers for man-db (2.7.5-1) ...
   Setting up qemu-user-static (1:2.5+dfsg-5ubuntu10.51) ...
   

2. 安装编译MIPS架构的GCC工具：

   $ apt install gcc-mips-linux-gnu
   Reading package lists... Done
   Building dependency tree
   Reading state information... Done
   The following additional packages will be installed:
   

3. 编写测试程序进行测试

   $ more xx.c
   #include <stdio.h>
   #include <endian.h>
   
   int main()
   {
       int x = 0x1234;
       printf("0x%x, htole32 0x%x, htobe32 0x%x\n", x, htole32(x), htobe32(x));
       return 0;
   }
   

4. 编译，可看出编译出的程序时MSB，大端序的。

   需要注意的是要加上 -static的编译选项否则运行时候会提示找不到链接库。

   $ mips-linux-gnu-gcc -static xx.c
   [root@ubuntu] ~
   $ file a.out
   a.out: ELF 32-bit MSB executable, MIPS, MIPS32 rel2 version 1 (SYSV), statically linked, for GNU/Linux 3.2.0, BuildID[sha1]=48929411066f86d58ed7855e545b980bc92fd75b, not stripped
   

5. 运行

   $ qemu-mips-static ./a.out
   0x1234, htole32 0x34120000, htobe32 0x1234