git clone https://github.com/torvalds/linux.git
sudo apt-get install gcc-arm-linux-gnueabi
make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm vexpress_defconfig
Generated .config as below,
#
# Automatically generated file; DO NOT EDIT.
# Linux/arm 3.16.0 Kernel Configuration
#
make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm
~/work/src/linux/linux/arch/arm/boot$ ll
-rwxrwxr-x 1 peter peter 3325088 3月 19 16:36 zImage*
-rw-rw-r-- 1 peter peter 134 3月 19 16:36 .zImage.cmd
wget http://wiki.qemu-project.org/download/qemu-2.0.2.tar.bz2
tar -jxvf qemu-2.0.2.tar.bz2
sudo apt-get install zlib1g-dev
sudo apt-get install libglib2.0-0
sudo apt-get install libglib2.0-dev
./configure --target-list=arm-softmmu --audio-drv-list=
make
make install
qemu-system-arm -M vexpress-a9 -m 512M -kernel /home/peter/work/src/linux/linux/arch/arm/boot/zImage -nographic -append "console=ttyAMA0"
Kernel launched, but error Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) occurred which means lack of rootfs.
VFS: Cannot open root device "(null)" or unknown-block(0,0): error -6
Please append a correct "root=" boot option; here are the available partitions:
1f00 131072 mtdblock0 (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
根文件系统 = busybox(包含基础的Linux命令) + 运行库 + 几个字符设备
本文直接使用SD卡做为存储空间，文件格式为ext3格式
Download busybox,
wget http://www.busybox.net/downloads/busybox-1.20.2.tar.bz2
Or download from `http://linux.linuxidc.com/index.php?folder=cHViL0J1c3lib3g=` in China :).
Generate _install as below,
sudo make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- defconfig
sudo make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- install
安装完成后，会在busybox目录下生成_install目录，该目录下的程序就是单板运行所需要的命令。
Building a Root File System using BusyBox. For cpio, refer to cpio -o .
Create image as below,
sudo mkdir rootfs
sudo cp _install/* -r rootfs/
sudo mkdir rootfs/lib
sudo cp -P /usr/arm-linux-gnueabi/lib/* rootfs/lib/
sudo mknod rootfs/dev/tty1 c 4 1
sudo mknod rootfs/dev/tty2 c 4 2
sudo mknod rootfs/dev/tty3 c 4 3
sudo mknod rootfs/dev/tty4 c 4 4
dd if=/dev/zero of=a9rootfs.ext3 bs=1M count=32
mkfs.ext3 a9rootfs.ext3
sudo mkdir tmpfs
sudo mount -t ext3 a9rootfs.ext3 tmpfs/ -o loop
sudo cp -r rootfs/* tmpfs/
sudo umount tmpfs
Launch QEMU,
qemu-system-arm -M vexpress-a9 -m 512M -kernel /home/peter/work/src/linux/linux/arch/arm/boot/zImage -nographic -append "root=/dev/mmcblk0 console=ttyAMA0" -sd a9rootfs.ext3
execution log for creating rootfs
To see the help use
(qemu)
C-a h print this help
C-a x exit emulator
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
C-a C-a sends C-a
这里简单介绍下qemu命令的参数：
-M vexpress-a9 模拟vexpress-a9单板，你可以使用-M ?参数来获取该qemu版本支持的所有单板
-m 512M 单板运行物理内存512M
-kernel /home/ivan/kernel_git/linux/arch/arm/boot/zImage 告诉qemu单板运行内核镜像路径
-nographic 不使用图形化界面，只使用串口
-append "console=ttyAMA0" 内核启动参数，这里告诉内核vexpress单板运行，串口设备是哪个tty。
Run qemu-system-arm -h for more info.
In terminal 1:
# gdb-multiarch -x .gdbinit vmlinux
In terminal 2:
qemu-2.0.2# qemu-system-arm -M vexpress-a9 -m 512M -kernel /home/baohua/develop/linux/arch/arm/boot/zImage -nographic -append "console=ttyAMA0" -s -S
-S freeze CPU at startup (use 'c' to start execution)
-s shorthand for -gdb tcp::1234
How to use gdb to debug ARM kernel in Qemu
An error occurred while executing make CROSS_COMPILE=arm-linux-gnueabi- error: storage size of ‘rlimit_fsize’ isn’t known. Fix it with updating include/platform.h and add #include <sys/resource.h>
Refer to error: storage size of ‘rlimit_fsize’ isn’t known
While compiling QEMU if below problem occurred,
configure.ac:75: error: possibly undefined macro: AC_PROG_LIBTOOL
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
fix it with below,
sudo apt-get install libtool
error: possibly undefined macro: AC_PROG_LIBTOOL
If below problem occurred while installing QEMU,
peter@peter-ThinkPad-T430:~/work/src/qemu-2.0.2$ make install
make all-recursive
Making all in pixman
make all-am
make[4]: Nothing to be done for `all-am'.
Making all in test
make[3]: Nothing to be done for `all'.
LEX convert-dtsv0-lexer.lex.c
make[1]: flex: Command not found
BISON dtc-parser.tab.c
make[1]: bison: Command not found
LEX dtc-lexer.lex.c
make[1]: flex: Command not found
CHK version_gen.h
install -d -m 0755 "/usr/local/share/doc/qemu"
install: cannot change permissions of ‘/usr/local/share/doc/qemu’: No such file or directory
make: *** [install-doc] Error 1
fix it with
sudo make install
EXT3-fs (mmcblk0): mounted filesystem with writeback data mode VFS: Mounted root (ext3 filesystem) readonly on device 179:0. Freeing unused kernel memory: 244K (805c0000 - 805fd000) random: nonblocking pool is initialized can’t run ‘/etc/init.d/rcS’: No such file or directory
Please press Enter to activate this console.
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