gem5全系统模拟

陆续写些关于新书《自己动手写CPU》的博客，本篇主要是讲解 gem5运行全系统模拟

使用gem5可以启动Linux内核，称为全系统模拟，启动之后，可以通过telent连接，进行访问，但四telent有时不稳定，gem5推荐使用m5term进行连接访问，整个步骤如下：

（假设gem5文件加压缩后，位于/root/gem5/gem5-stable-50ff05095970文件夹）

（1）打开终端，进入/root/gem5/gem5-stable-50ff05095970目录，使用如下命令得到x86的二进制虚拟机

scons build/X86/gem5.opt 

时间比较长，大约半个小时。

（2）在http://www.m5sim.org/Download下载x86对应的全系统文件，我用的下载地址是http://www.m5sim.org/dist/current/x86/x86-system.tar.bz2

下载后，在/root/gem5/gem5-stable-50ff05095970目录下新建一个文件夹fs-image，将下载的x86-system.tar.bz2复制到该文件夹下，并解压缩。

（3）在http://www.m5sim.org/Download下载alpha对应的全系统文件，我用的下载地址是http://www.m5sim.org/dist/current/m5_system_2.0b3.tar.bz2

下载后，解压缩，将其中disks目录下的linux-bigswap2.img复制到/root/gem5/gem5-stable-50ff05095970/fs-image/x86-system/disks目录下。

（4）修改/root/.bashrc，其中添加环境变量，如下：

export M5_PATH=$M5_PATH:/root/gem5/gem5-stable-50ff05095970/fs-image/x86-system

使用source /root/.bashrc，使得修改后的环境变量生效。

（5）在终端中进入/root/gem5/gem5-stable-50ff05095970目录，是如如下命令可以启动x86虚拟机：

build/X86/gem5.opt configs/example/fs.py --kernel=x86_64-vmlinux-2.6.22.9 --disk-image=linux-x86.img

会出现如下启动结果：

gem5 Simulator System.  http://gem5.orggem5 is copyrighted software; use the --copyright option for details.gem5 compiled Jan 26 2015 13:54:19gem5 started Jan 26 2015 18:19:14gem5 executing on localhost.localdomaincommand line: build/X86/gem5.opt configs/example/fs.py --kernel=x86_64-vmlinux-2.6.22.9 --disk-image=linux-x86.imgGlobal frequency set at 1000000000000 ticks per secondinfo: kernel located at: /root/gem5/gem5-stable-50ff05095970/fs-image/x86-system/binaries/x86_64-vmlinux-2.6.22.9      0: rtc: Real-time clock set to Sun Jan  1 00:00:00 2012Listening for com_1 connection on port 3456warn: Reading current count from inactive timer.0: system.remote_gdb.listener: listening for remote gdb #0 on port 7000**** REAL SIMULATION ****info: Entering event queue @ 0.  Starting simulation...warn: Don't know what interrupt to clear for console.53268325000: system.pc.com_1.terminal: attach terminal 0warn: x86 cpuid: unknown family 0x8086

其中提示的监听端口是3456，这也是默认的监听端口。

接下来可以编译m5term，以便连接到上面的监听端口，m5term的源码在gem5源代码的util/term目录下，进入该目录，输入熟悉命令进行编译：

        % cd m5/util/term % makegcc  -o m5term term.c% make installsudo install -o root -m 555 m5term /usr/local/bin

然后使用如下命令连接虚拟机：

./m5term 127.0.0.1 3456

会出现如下启动文字：

[root@localhost term]# ./m5term 127.0.0.1 3456==== m5 slave terminal: Terminal 0 ====Linux version 2.6.22.9 (blackga@nacho) (gcc version 4.1.2 (Gentoo 4.1.2)) #2 Mon Oct 8 13:13:00 PDT 2007Command line: earlyprintk=ttyS0 console=ttyS0 lpj=7999923 root=/dev/hda1BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) BIOS-e820: 000000000009fc00 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 0000000020000000 (usable) BIOS-e820: 00000000ffff0000 - 0000000100000000 (reserved)end_pfn_map = 1048576kernel direct mapping tables up to 100000000 @ 8000-d000DMI 2.5 present.Zone PFN ranges:  DMA             0 ->     4096  DMA32        4096 ->  1048576  Normal    1048576 ->  1048576early_node_map[2] active PFN ranges    0:        0 ->      159    0:      256 ->   131072Intel MultiProcessor Specification v1.4MPTABLE: OEM ID:  MPTABLE: Product ID:  MPTABLE: APIC at: 0xFEE00000Processor #0 (Bootup-CPU)I/O APIC #1 at 0xFEC00000.Setting APIC routing to flatProcessors: 1swsusp: Registered nosave memory region: 000000000009f000 - 00000000000a0000swsusp: Registered nosave memory region: 00000000000a0000 - 0000000000100000Allocating PCI resources starting at 30000000 (gap: 20000000:dfff0000)Built 1 zonelists.  Total pages: 127572Kernel command line: earlyprintk=ttyS0 console=ttyS0 lpj=7999923 root=/dev/hda1Initializing CPU#0PID hash table entries: 2048 (order: 11, 16384 bytes)time.c: Detected 1999.998 MHz processor.Console: colour dummy device 80x25console handover: boot [earlyser0] -> real [ttyS0]Dentry cache hash table entries: 65536 (order: 7, 524288 bytes)Inode-cache hash table entries: 32768 (order: 6, 262144 bytes)Checking aperture...Memory: 509256k/524288k available (3742k kernel code, 14436k reserved, 1874k data, 232k init)Calibrating delay loop (skipped)... 3999.96 BogoMIPS presetMount-cache hash table entries: 256CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)CPU: L2 Cache: 1024K (64 bytes/line)CPU: Fake M5 x86_64 CPU stepping 01ACPI: Core revision 20070126ACPI Exception (tbxface-0618): AE_NO_ACPI_TABLES, While loading namespace from ACPI tables [20070126]ACPI: Unable to load the System Description TablesUsing local APIC timer interrupts.result 7812510Detected 7.812 MHz APIC timer.NET: Registered protocol family 16PCI: Using configuration type 1ACPI: Interpreter disabled.Linux Plug and Play Support v0.97 (c) Adam Belaypnp: PnP ACPI: disabledSCSI subsystem initializedusbcore: registered new interface driver usbfsusbcore: registered new interface driver hubusbcore: registered new device driver usbPCI: Probing PCI hardwarePCI-GART: No AMD northbridge found.Time: tsc clocksource has been installed.NET: Registered protocol family 2IP route cache hash table entries: 16384 (order: 5, 131072 bytes)TCP established hash table entries: 65536 (order: 8, 1048576 bytes)TCP bind hash table entries: 65536 (order: 7, 524288 bytes)TCP: Hash tables configured (established 65536 bind 65536)TCP reno registeredTotal HugeTLB memory allocated, 0Installing knfsd (copyright (C) 1996 [e-mail]).io scheduler noop registeredio scheduler deadline registeredio scheduler cfq registered (default)Real Time Clock Driver v1.12acLinux agpgart interface v0.102 (c) Dave JonesSerial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing disabledserial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 8250floppy0: no floppy controllers foundRAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksizeloop: module loadedIntel(R) PRO/1000 Network Driver - version 7.3.20-k2Copyright (c) 1999-2006 Intel Corporation.e100: Intel(R) PRO/100 Network Driver, 3.5.17-k4-NAPIe100: Copyright(c) 1999-2006 Intel Corporationforcedeth.c: Reverse Engineered nForce ethernet driver. Version 0.60.tun: Universal TUN/TAP device driver, 1.6tun: (C) 1999-2004 Max Krasnyansky <[e-mail]>netconsole: not configured, abortingUniform Multi-Platform E-IDE driver Revision: 7.00alpha2ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xxPIIX4: IDE controller at PCI slot 0000:00:04.0PCI: Enabling device 0000:00:04.0 (0000 -> 0001)PIIX4: chipset revision 0PIIX4: not 100% native mode: will probe irqs later    ide0: BM-DMA at 0x1000-0x1007, BIOS settings: hda:DMA, hdb:DMA    ide1: BM-DMA at 0x1008-0x100f, BIOS settings: hdc:DMA, hdd:DMAhda: M5 IDE Disk, ATA DISK drivehdb: M5 IDE Disk, ATA DISK driveide0 at 0x1f0-0x1f7,0x3f6 on irq 14hda: max request size: 128KiBhda: 1048320 sectors (536 MB), CHS=1040/16/63, UDMA(33) hda: hda1hdb: max request size: 128KiBhdb: 4177920 sectors (2139 MB), CHS=4144/16/63, UDMA(33) hdb: unknown partition tablemegaraid cmm: 2.20.2.7 (Release Date: Sun Jul 16 00:01:03 EST 2006)megaraid: 2.20.5.1 (Release Date: Thu Nov 16 15:32:35 EST 2006)megasas: 00.00.03.10-rc5 Thu May 17 10:09:32 PDT 2007Fusion MPT base driver 3.04.04Copyright (c) 1999-2007 LSI Logic CorporationFusion MPT SPI Host driver 3.04.04Fusion MPT SAS Host driver 3.04.04ieee1394: raw1394: /dev/raw1394 device initializedUSB Universal Host Controller Interface driver v3.0usbcore: registered new interface driver usblpdrivers/usb/class/usblp.c: v0.13: USB Printer Device Class driverInitializing USB Mass Storage driver...usbcore: registered new interface driver usb-storageUSB Mass Storage support registered.PNP: No PS/2 controller found. Probing ports directly.serio: i8042 KBD port at 0x60,0x64 irq 1serio: i8042 AUX port at 0x60,0x64 irq 12mice: PS/2 mouse device common for all miceinput: AT Translated Set 2 keyboard as /class/input/input0device-mapper: ioctl: 4.11.0-ioctl (2006-10-12) initialised: [e-mail]: PS/2 Generic Mouse as /class/input/input1usbcore: registered new interface driver usbhiddrivers/hid/usbhid/hid-core.c: v2.6:USB HID core driveroprofile: using timer interrupt.TCP cubic registeredNET: Registered protocol family 1NET: Registered protocol family 10IPv6 over IPv4 tunneling driverNET: Registered protocol family 17EXT2-fs warning: mounting unchecked fs, running e2fsck is recommendedVFS: Mounted root (ext2 filesystem).Freeing unused kernel memory: 232k freedINIT: version 2.86 bootingmounting filesystems...loading script...Script from M5 readfile is empty, starting bash shell...(none) / #

最后启动shell了，可以输入命令，如下：

(none) / # lsbin   dev  home  lib32  lost+found  opt   root  sys  usrboot  etc  lib   lib64  mnt         proc  sbin  tmp  var