背景
上篇博客写了如何在gem5的full system模式运行alpha的指令编译的程序，这篇博客讲述如何在gem5的full system模式运行x86指令集编译的程序，这两种方式非常类似。
首先需要安装gem5-stable，可以参考我前面的一篇博客：
http://blog.****.net/wyj7260/article/details/8267345
这篇文章介绍full system in x86。
安装过程：
下载full system需要的两个包：
首先在安装好gem5-stable之后，再到官网下载full system需要的包：
Full System Files : http://www.m5sim.org/dist/current/x86/x86-system.tar.bz2
Config files : http://www.m5sim.org/dist/current/x86/config-x86.tar.bz2
安装：记我的gem5-stable安装目录为$GEM
a) ~/gem5-stable$ mkdir x86Dist
b) 将包x86-system.tar.bz2和config-x86.tar.bz2复制到x86Dist目录下
b) ~/gem5-stable$ cd x86Dist/
c) ~/gem5-stable/x86Dist$ tar -xvf x86-system.tar.bz2
把exceptKeyError:
path = [ '/dist/m5/system', '/n/poolfs/z/dist/m5/system
修改成
except KeyError:
path = [ '/dist/m5/system', ' /home/wyj2/gem5-stable/x86Dist' ]
运行(运行过程中遇到的error以及解决方法)
1、 首先编译gem5.opt
~/gem5-stable $ scons ./build/x86/gem5.opt
2、运行模拟的linux系统
~/gem5-stable$ ./build/X86/gem5.opt ./configs/example/fs.py
报错如下：
gem5 Simulator System. http://gem5.org
gem5 is copyrighted software; use the --copyright option for details.
gem5 compiled Jul 12 2013 21:30:39
gem5 started Jul 12 2013 21:33:06
gem5 executing on arch-node3
command line: ./build/X86/gem5.opt ./configs/example/fs.py
warning: add_child('terminal'): child 'terminal' already has parent
Global frequency set at 1000000000000 ticks per second
info: No kernel set for full system simulation. Assuming you know whatyou're doing if not SPARC ISA
0: rtc: Real-time clock setto Sun Jan 1 00:00:00 2012
panic: Error opening /home/wyj/gem5-stable/x86Dist/disks/x86root.img
@ cycle 0
[open:build/X86/dev/disk_image.cc, line 79]
Memory Usage: 225092 KBytes
Program aborted at cycle 0
Aborted (core dumped)
解决方法：
提示不能打开x86root.img，于是我查找x86root.img
命令：~/gem5-stable$ grep -r"x86root.img" ./
得到如下：
./configs/common/Benchmarks.py: return env.get('LINUX_IMAGE',disk('x86root.img'))
如实修改Benchmarks.py, 把return env.get('LINUX_IMAGE',disk('x86root.img'))改成
return env.get('LINUX_IMAGE', disk('linux-x86.img'))
然后执行：
~/gem5-stable$ ./build/X86/gem5.opt ./configs/example/fs.py
gem5 Simulator System. http://gem5.org
gem5 is copyrighted software; use the --copyright option for details.
gem5 compiled Jul 2 201310:06:26
gem5 started Jul 13 2013 18:13:18
gem5 executing on jsi-desktop
command line: ./build/X86/gem5.opt ./configs/example/fs.py
warn: add_child('terminal'): child 'terminal' already has parent
Global frequency set at 1000000000000 ticks per second
info: No kernel set for full system simulation. Assuming you know whatyou're doing
0: rtc: Real-time clock setto Sun Jan 1 00:00:00 2012
panic: Error opening/home/wyj2/gem5-stable/x86Dist/disks/linux-bigswap2.img
@ cycle 0
[open:build/X86/dev/disk_image.cc, line 79]
Memory Usage: 177860 KBytes
Program aborted at cycle 0
Aborted
缺少linux-bigswap2.img文件，秩序要将alpha的full system下载的包Full System Files解压后的linux-bigswap2.img拷贝到目录/home/wyj2/gem5-stable/x86Dist/disks/就行。
（full system Files下载地址http://www.m5sim.org/dist/current/m5_system_2.0b3.tar.bz2解压也可得）
运行
~/gem5-stable$ ./build/X86/gem5.opt ./configs/example/fs.py
仍然报错
gem5 Simulator System. http://gem5.org
gem5 is copyrighted software; use the --copyright option for details.
gem5 compiled Jul 2 201310:06:26
gem5 started Jul 13 2013 18:18:48
gem5 executing on jsi-desktop
command line: ./build/X86/gem5.opt ./configs/example/fs.py
warn: add_child('terminal'): child 'terminal' already has parent
Global frequency set at 1000000000000 ticks per second
info: No kernel set for full system simulation. Assuming you know whatyou're doing
0: rtc: Real-time clock setto Sun Jan 1 00:00:00 2012
Listening for com_1 connection on port 3456
warn: Reading current count from inactive timer.
0: system.remote_gdb.listener: listening for remote gdb #0 on port 7000
fatal: No kernel to load.@ cycle 0
[initState:build/X86/arch/x86/system.cc, line 118]
Memory Usage: 177868 KBytes
这是因为运行时需要制定kernel：
运行命令为：
./build/X86/gem5.opt ./configs/example/fs.py --kernel=x86_64-vmlinux-2.6.22.9.smp
注意：此处不用制定.smp文件的路径，只用文件名就行
剩下的mount文件到模拟的系统同上一篇关于alpha的full system
。
参考链接：
http://www.m5sim.org/Running_M5_in_Full-System_Mode
http://novel.ict.ac.cn/qguo/pdf/gem5.pdf
http://gem5.org/dist/tutorials/hipeac2012/gem5_hipeac.pdf
以及参考师兄的ppt