Using QEMU to emulate debug kernel and Debian root file system

Development environment: Ubuntu 14.04.3 LTS 64bit

sudo debootstrap Jessie/mnt/jessie Http://mirrors.163.com/debian

In the/mnt/jessie directory, create an init file that reads as follows:

 [Email protected]380 : ~$ sudo  Span style= "COLOR: #0000ff" >vi /mnt/jessie/init # !/bin/sh  # Devtmpfs does not get automounted  for   Initramfs  echo   " ******** init **********   "/bin/mount -t Devtmpfs Devtmpfs/devexec  0  </dev/ consoleexec  1  >/dev/consoleexec  2  >/dev/consoleexec /sbin/init $* 

Refer to the Linux kernel documentation documentation/filesystems/ramfs-rootfs-initramfs.txt and use the script below to package Initramfs

[Email protected]380:/mnt$CatMkinitramfs.SH #!/bin/SH# Copyright2006Rob Landley <[email protected]>and Timesys corporation.# Licensed under GPL version2if[$#-ne2 ] Then  Echo "Usage:mkinitramfs Directory imagename.cpio.gz"Exit1fiif[-D" $" ] Then  Echo "creating $ from $"(CD" $";Find. | Cpio-o-H NEWC |gzip) >" $"Else  Echo "First argument must be a directory"Exit1fi

Package Command:

mkinitramfs.sh Jessie Rootfs.cpio.gz

Use the following command to start the kernel and root file system:

Qemu-system-x86_64-kernel bzimage-initrd/mnt/rootfs.cpio.gz/dev/zero-m 2g-nographic-append "Console=ttyS0"

Issue: Unable to enter INITRAMFS at startup because there is no init file under the root directory.

[11.815891] Rtc_cmosxx:xx: Setting system clock to -- A- Geneva  -: +: -UTC (1449040919)[   11.818523] BIOS EDD facility v0. - 2004-jun- -,0Devices found[11.818900] EDD information not available. [   11.819783] ALSA device list:[11.819991] No soundcards found. [   12.396667] Input:imexps/2Generic Explorer Mouse as/devices/platform/i8042/serio1/input/input3[12.403434] Vfs:cannot Open Root device"(NULL)"or Unknown-block (0,0): Error-6[   12.403941] Please append a correct"root="boot option; here is the available partitions:[12.404870] Kernel Panic-not syncing:VFS:Unable toMountRoot FS on Unknown-block (0,0)[   12.405584] CPU:0Pid:1comm:swapper/0Not tainted3.13.0#7[   12.405945] Hardware Name:qemu Standard PC (i440fx + Piix,1996), BIOS Bochs on/ on/ .[   12.406561]0000000000008001ffff880074d01dd0 ffffffff81b8de3a ffffffff8201c2c8[12.407087] ffff880074d01e48 ffffffff81b89a24 223d746f00000010 ffff880074d01e58[12.407557] Ffff880074d01df8 000000000000004f ffff880074d01e680000000000000052[   12.408077] Call trace:[12.408502] [<ffffffff81b8de3a>] dump_stack+0x45/0x56[   12.408502] [<ffffffff81b89a24>] panic+0xc2/0X1C1[   12.408502] [<ffffffff8234e338>] mount_block_root+0x1a8/0x250[   12.408502] [<ffffffff8234e61b>] mount_root+0xf1/0XFA[   12.408502] [<ffffffff8234f2a0>]? Initrd_load+0X2C9/0x2d8[   12.408502] [<ffffffff8234e78b>] prepare_namespace+0x167/0x19f[   12.408502] [<ffffffff8234e04a>] Kernel_init_freeable+0x1c4/0x1d1[   12.408502] [<ffffffff8234d833>]? do_early_param+0x88/0x88[   12.408502] [<ffffffff81b85b00>]? rest_init+0x80/0x80[   12.408502] [<ffffffff81b85b0e>] kernel_init+0xe/0x120[   12.408502] [<ffffffff81b9f2ac>] ret_from_fork+0x7c/0xb0[   12.408502] [<ffffffff81b85b00>]? rest_init+0x80/0x80[   12.408502] General Protection FAULT:FFF2 [#1] SMP [12.408502] Modules Linkedinch:[   12.408502] CPU:0Pid:1comm:swapper/0Not tainted3.13.0#7[   12.408502] Hardware Name:qemu Standard PC (i440fx + Piix,1996), BIOS Bochs on/ on/ .[   12.408502] task:ffff880074c58000 ti:ffff880074d00000 task.ti:ffff880074d00000[12.408502] RIP:0010: [<ffffffff81b89aea>] [<ffffffff81b89aea>] panic+0x188/0X1C1[   12.408502] RSP:0018: Ffff880074d01de0 eflags:00000246[   12.408502] rax:0000000000006a6a rbx:ffffffff8201c2c8 rcx:00000000000000a0[12.408502] rdx:000000000000006a RSI:0000000000000000rdi:ffffffff826c8a70[12.408502] Rbp:ffff880074d01e48 R08:0000000000000001r09:00000000000001e1[12.408502] r10:736572203f205d3e R11:3030623538623138R12:0000000000000000[   12.408502] R13:0000000000000000R14:0000000000000000r15:ffff88007fa93000[12.408502] FS:0000000000000000(0000) gs:ffff880077800000 (0000) Knlgs:0000000000000000[   12.408502] CS:0010Ds:0000Es:0000cr0:000000008005003b[12.408502] cr2:00007fbb08c44140 cr3:000000000220c000 cr4:00000000000006f0[12.408502] DR0:0000000000000000DR1:0000000000000000DR2:0000000000000000[   12.408502] DR3:0000000000000000DR6:0000000000000000DR7:0000000000000000[   12.408502] stack:[12.408502] 223d746f00000010 ffff880074d01e58 ffff880074d01df8 000000000000004f[12.408502] Ffff880074d01e680000000000000052ffff880000095070 6120657361656c50[12.408502] 00000000000001ce ffff88007fa930000000000000008001 0000000000008001[   12.408502] Call trace:[12.408502] [<ffffffff8234e338>] mount_block_root+0x1a8/0x250[   12.408502] [<ffffffff8234e61b>] mount_root+0xf1/0XFA[   12.408502] [<ffffffff8234f2a0>]? Initrd_load+0X2C9/0x2d8[   12.408502] [<ffffffff8234e78b>] prepare_namespace+0x167/0x19f[   12.408502] [<ffffffff8234e04a>] Kernel_init_freeable+0x1c4/0x1d1[   12.408502] [<ffffffff8234d833>]? do_early_param+0x88/0x88[   12.408502] [<ffffffff81b85b00>]? rest_init+0x80/0x80[   12.408502] [<ffffffff81b85b0e>] kernel_init+0xe/0x120[   12.408502] [<ffffffff81b9f2ac>] ret_from_fork+0x7c/0xb0[   12.408502] [<ffffffff81b85b00>]? rest_init+0x80/0x80[   12.408502] Code:xx xx  theFfcc  About0c BF -  the  A xxE8 E0 -  theFF EB ef -  theC3 -EB b6 the3d A1 the  the xx xx  About  toE8 5a 3f 4e FF FB $  toE4 <4d> theEC 7c -  A  theF6 on  -  theF7 FF the  -  the  the xx  the  onC4 [12.408502] RIP [<ffffffff81b89aea>] panic+0x188/0X1C1[   12.408502] RSP <ffff880074d01de0>[   12.408502]---[end trace 96badb4295b8f792]---

QEMU provides several shortcut keys, CTRL + A h open Help

C-a h Print this help

C-a x Exit emulator Exit

C-A s save disk data back to file (If-snapshot)

C-a T Toggle console timestamps

C-a b Send Break (Magic SysRq)

C-a C Switch between console and monitor switch between the Linux console and the QEMU control terminal

C-a C-a sends C-a

Using QEMU to emulate debug kernel and Debian root file system