Setup Arm Development Environment
2017-12-31 by terryoy, in guides
1. Clone the kernel repository
$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
# or just download the package from the mirror
$ wget https://mirror.tuna.tsinghua.edu.cn/kernel/v4.x/linux-4.4.1.tar.xz
2. Install the Cross Compiling Toolchain
$ sudo apt-get install gcc-arm-linux-gnueabi
# another option is "arm-linux-gnueabihf" but we use "gcc-arm-gnueabi" here
3. Make the first compile
We're emulating the vexpress Cortex A9 for demo.
$ export ARCH=arm
$ export CROSS_COMPILE=arm-linux-gnueabi-
$ make vexpress_defconfig
$ make zImage -j8
$ make modules -j8
$ make dtbs
4. Install QEMU
$ sudo apt-get install qemu
5. Make Root File System
5.1 busybox
$ wget http://www.busybox.net/downloads/busybox-1.25.1.tar.bz2
$ tar xvf busybox-1.25.1.tar.bz2
$ make defconfig
$ make CROSS_COMPILE=arm-linux-gnueabi-
$ make install CROSS_COMPILE=arm-linux-gnueabi-
Then you find the executables in _install folder. Next we start to create the rootfs.
5.2 rootfs
$ sudo mkdir rootfs
$ sudo mkdir rootfs/lib
# copy busybox to rootfs
$ sudo cp _install/* -r rootfs/
# copy arm libs to lib
# sudo cp -P /usr/arm-linux-gnueabi/lib/* rootfs/lib/
5.3 Create 4 tty devices
$ sudo mkdir -p rootfs/dev
$ 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
You can also create other folders in the image. (Reference: learningfromyoublog.wordpress.com/2016/04/05/131/)
5.4 Make the Image
# creat an empty image
$ dd if=/dev/zero of=a9rootfs.ext3 bs=1M count=32
# format to ext3
$ mkfs.ext3 a9rootfs.ext3
# copy files into the image
$ sudo mkdir tmpfs
$ sudo mount -t ext3 a9rootfs.ext3 tmpfs/ -o loop
$ sudo cp -r rootfs/* tmpfs/
$ sudo umount tmpfs
6. Start QEMU with the Image
# open in current console
$ qemu-system-arm -M vexpress-a9 -m 512M -dtb extra_folder/vexpress-v2p-ca9.dtb -kernel extra_folder/zImage -nographic -append "root=/dev/mmcblk0 rw console=ttyAMA0" -sd a9rootfs.ext3
# open in new window(maybe GUI)
$ qemu-system-arm -M vexpress-a9 -m 512M -dtb extra_folder/vexpress-v2p-ca9.dtb -kernel extra_folder/zImage -append "root=/dev/mmcblk0 rw" -sd a9rootfs.ext3
Now you enter the console of the emulator system. Press Ctrl+A C to exit to (qemu) console, or Ctrl+A X to exit..