This post is about creating a simple file system and load with QEMU(X86).
Requirements
- QEMU
- Kernel BzImage
- Busy box
Step 1: For Installing QEMU on ubuntu machine
sudo apt-get install qemu-system
Step 2: Download kernel from kernel.org and compile the kernel for bzImage
Step 3: Download the busybox from http://git.busybox.net/busybox/?h=1_22_stable
/* Create a folder for holding folders*/
$ mkdir myfilesys
/* Go to busybox folder and compile*/
$ make menuconfig <-- In this step select "Statically linked busybox"
$ make
$ make install CONFIG_PREFIX=path/to/myfilesys
/* Create the standard directories */
$ mkdir dev etc etc/init.d bin proc mnt tmp var var/shm
$ chmod 755 . dev etc etc/init.d bin proc mnt tmp var var/shm
/* dev folder settings */
$ mknod tty c 5 0
$ mknod console c 5 1
$ chmod 666 tty console
$ mknod tty0 c 4 0
$ chmod 666 tty0
$ mknod ram0 b 1 0
$ chmod 600 ram0
$ mknod null c 1 3
$ chmod 666 null
/* etc folder settings */
$ cd myfilesys/etc/
$ vi init.d/rcS <-- Create a file name "rcS" and add the following command
#! /bin/sh
mount -a # Mount the default file systems mentioned in /etc/fstab.
$ chmod 744 init.d/rcS
$ vi fstab <-- Create fstab file and copy the following content
proc /proc proc defaults 0 0
none /var/shm shm defaults 0 0
$ chmod 644 fstab
$ vi inittab <-- Create inittab file
::sysinit:/etc/init.d/rcS
::askfirst:/bin/sh
$ chmod 644 inittab
/* Create an ext2 filesystem image by running these commands */
$ dd if=/dev/zero of=my.img bs=1M count=2
$ mkfs.ext2 -N 512 my.img
/* mount the filesystem and copy the folders which created early (myfilesys contents)*/
$ mount -t ext2 my.img /mnt
$ cp -fr myfilesys/* /mnt
$ umount /mnt
Step 4: Now we have bzImage, file system and installed QEMU. Issue the following command for loading our images.
$ qemu-system-i386 -kernel bzImage -hda my.img -append=/dev/sda
Now QEMU loads newly build kernel and file system. Hurrayyyyyyy !!! We made it. If you want to explore further , try creating new directories, do some extra stuff :)
References
Hey,Jey.Thanks for your post!This article just helped me a lot.But i think the BusyBox should be static builed,or the Linux kernel can't mount the img file rightly.
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