Linux 3.10 busybox Initramfs building QEMU debugging

Linux 3.10 busybox InitramfsBuildQemuDebug

My environment is a CentOS 7 64-bit system run by VM Ware virtual machine

1: InstallationQemu

First install SDL, responsible for QEMU running only after the VNC server running on ':: 1:5900 ', and does not appear Qemu Run the window, for specific reference:

http://www.crifan.com/qemu_test_arm_vnc_server_running_on_127_0_0_1_5900_no_other_output/

Yum install sdl.i686 sdl.x86_64 sdl-devel.i686 sdl-devel.x86_64

Download source code qemu-2.1.0.tar.bz2, unzip the compilation, install

./configure--prefix=/usr/local/--target-list=x86_64-softmmu

Make && make install

Create a soft link

Ln-n/usr/local//bin/qemu-system-x86_64/bin/qemu

2:DownloadBUSYBOX-1.20.0.TAR.BZ2, unzip, go to source code directory, run

Make Menuconfig

Choose

Busybox Settings--->

Build Options--->

[*] Build BusyBox as a static binary (no shared libs)

Compiling the installation

Make && make install

Error occurred during compilation

CC LOGINUTILS/PASSWD.O

LOGINUTILS/PASSWD.C: in the function 'passwd_main' :

Loginutils/passwd.c:104:16: error: 'rlimit_fsize' storage size is unknown

struct Rlimit rlimit_fsize;

^

Loginutils/passwd.c:188:2: Warning: Implicitly declaring function 'setrlimit' [-wimplicit-function-declaration ]

Setrlimit (Rlimit_fsize, &rlimit_fsize);

^

Loginutils/passwd.c:188:12: error: 'rlimit_fsize' not declared ( First Use within this function )

Setrlimit (Rlimit_fsize, &rlimit_fsize);

^

Loginutils/passwd.c:188:12: Note: Each undeclared identifier is reported only once within the function in which it appears

Loginutils/passwd.c:104:16: Warning: Unused variable 'rlimit_fsize' [-wunused-variable]

Vim Include/libbb.h

Add in # include <sys/mman.h> back

#include <sys/resource.h>

Specific reference http://lists.busybox.net/pipermail/busybox/2012-May/077766.html

Compile a simple program to test

Vim ~/init.c

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

int main ()

{

while (1) {

printf ("Hello world!\n");

Sleep (199999999);

}

return 0;

}

Gcc-static ~/init.c-o/opt/busybox-1.20.0/_install/init

Cd/opt/busybox-1.20.0/_install

Mknod-m dev/console C 5 1

Go to create directory and file

CD _install

Mkdir-p Dev proc sys etc mnt

Touch etc/mdev.conf

Mknod-m dev/null C 1 3

Theinit script does not run correctly when you create a console device file and do not create this file . Initialization Code reference function for console:init/main.c:kernel_init_freeable

Mknod-m dev/console C 5 1

To create the init file:

VIM Init

The contents are as follows:

#!/bin/sh

Echo

echo "###########################################################"

echo "# # Author: [email protected] # # #"

echo "# # DATE:2014/09/15 16:57:21 CST # #"

echo "###########################################################"

Echo

Path= "/bin:/sbin:/usr/bin:/usr/sbin"

if [!-F "/bin/busybox"];then

echo "Cat not find BusyBox in/bin dir, exit"

Exit 1

Fi

busybox= "/bin/busybox"

echo "Build root filesystem ..."

$BUSYBOX--install-s

if [!-d/proc];then

echo "/proc dir not exist, create it ..."

$BUSYBOX Mkdir/proc

Fi

echo "Mount Proc FS ..."

$BUSYBOX mount-t proc Proc/proc

if [!-d/dev];then

echo "/dev dir not exist, create it ..."

$BUSYBOX Mkdir/dev

Fi

echo "Mount Tmpfs In/dev ..."

$BUSYBOX mount-t Tmpfs Dev/dev

$BUSYBOX mkdir-p/dev/pts

echo "Mount Devpts ..."

$BUSYBOX mount-t devpts devpts/dev/pts

if [!-d/sys];then

echo "/sys dir not exist, create it ..."

$BUSYBOX Mkdir/sys

Fi

echo "Mount Sys FS ..."

$BUSYBOX mount-t Sysfs Sys/sys

echo "/sbin/mdev" >/proc/sys/kernel/hotplug

echo "Populate the dev dir ..."

$BUSYBOX mdev-s

echo "drop to Shell ..."

$BUSYBOX SH

Exit 0

Permissions to execute on Init

chmod u+x Init

3:DownloadLINUX-3.10.TAR.XZ, unzip the source code, enter the source directory, run

Make Menuconfig

Configure compilation options, select

General Setup--->

[*] Initramfs source file (s)

option, enter the directory of the prepared file system and I'm here.

/opt/busybox-1.20.0/_install

Compile

Make Bzimage

To run a virtual machine:

Qemu-kernel./arch/x86/boot/bzimage-append "No_timer_check"

Commissioning of the GDP under another terminal :

GDB Vmlinux

Target Remote 127.0.0.1:1234

b Start_kernel

4: Do not add No_timer_check on my machine will output

... trying to set up timer as Virtual wire IRQ ...

Back stuck

Ways to solve this problem:

In the source code search trying to set the timer as Virtual wire IRQ, locate the function output statement in the function Check_timer.

Running virtual machines

Qemu-kernel./arch/x86/boot/bzimage-append "Root=/dev/hda init=/bin/sh no_timer_check"-s-s

Running in the kernel source code directory

GDB Vmlinux

Enter the command after entering the gdb command line

Target Remote 127.0.0.1:1234

b Check_timer

C

After the breakpoint is executed from the output trying to the set up timer as a Virtual wire IRQ, the Timer_irq_works function is found to be stuck. There are statements in Timer_irq_works:

if (No_timer_check)

return 1;

Find the No_timer_check and find the No_timer_check option in documentation/x86/x86_64/boot-options.txt.

5:gdbDebug Appearsgdb ' g ' packet reply is too longfixed,

after downloading gdb-7.8.tar.xz

Extract

Xt-d GDB-7.8.TAR.XZ

Tar XF gdb-7.8.tar.xz

Edit Source code:

Vim gdb/remote.c

Find the process_g_packet function

Note Adjust the following two lines

if (Buf_len > 2 * rsa->sizeof_g_packet)

Error (_ ("Remote ' G ' packet reply is too long:%s"), RS->BUF);

Add the following code later:

if (Buf_len > 2 * rsa->sizeof_g_packet) {

Rsa->sizeof_g_packet = Buf_len;

for (i = 0; i < Gdbarch_num_regs (gdbarch); i++) {

if (Rsa->regs->pnum = =-1)

Continue

if (Rsa->regs->offset >= rsa->sizeof_g_packet)

Rsa->regs->in_g_packet = 0;

Else

Rsa->regs->in_g_packet = 1;

}

}

Configuration compilation

./configure--prefix=/usr/local/gdb

Make && make install

Setting environment variables

Export Path=/usr/local/gdb/bin: $PATH

6:Other questions

execute directly under the Xshell

Qemu-kernel./arch/x86/boot/bzimage-append "No_timer_check"

The keyboard input will appear garbled. This behavior does not occur in virtual machine environments.

Linux 3.10 busybox Initramfs building QEMU debugging