Linux bootable disk image using EXTLINUX, buildroot

Steps to create a root filesystem using buildroot and run Linux kernel using QEMU

• Download buildroot

$ git clone git://git.buildroot.net/buildroot

• Update buildroot

$ cd buildroot
$ git pull

• Change configuration to build for i386

$ make menuconfig

• Build buildroot
  

$ make

• Run in QEMU
  

$ qemu -kernel /boot/vmlinuz -initrd /boot/initrd.img -hda binaries/uclibc/rootfs.i386.ext2 -append "root=/dev/sda rw" -m 1024

Steps to create a bootable disk image using EXTLINUX, buildroot, Linux kernel and run using QEMU

• Mount buildroot root filesystem

$ sudo mount binaries/uclibc/rootfs.i386.ext2 buildrootfs -o loop -t ext2

• Create disk image

$ dd if=/dev/zero of=rootfs.img bs=1M count=10

• Create ext2 filesystem

$ mke2fs -j rootfs.img
$ tune2fs -c 0 -i 0 rootfs.img

• Mount disk image

$ sudo mount rootfs.img rootfs -o loop -t ext2

• Copy buildroot to disk image
  

$ rsync -a buildrootfs/ rootfs

• Create boot directory
  

$ mkdir rootfs/boot

• Copy Linux kernel and initial ramdisk to boot directory
  

$ cp vmlinuz rootfs/boot
$ cp initrd.img rootfs/boot

• Install EXTLINUX bootloader
  

$ extlinux --install rootfs/boot
$ vi rootfs/boot/extlinux.conf
default linux
timeout 10
prompt 1

label linux
kernel /boot/vmlinuz
append initrd=/boot/initrd.img root=/dev/sda clocksource=kvm-clock

• Unmount disk image

$ sudo umount rootfs

• Run in QEMU
  

$ qemu -hda rootfs.img -m 1024