mount ARM (OdroidC1, Raspberry Pi,...) filesystem image, and chroot into it using qemu-user-static

armchroot.sh

#!/usr/bin/sudo /bin/bash

MOUNTPOINT=/mnt/odroidc1
FSIMG=${HOME}/odroidc1-sdcard-jessie.img
CHROOTNAME=`basename ${MOUNTPOINT}`

#DEBUG=1

if [ -z "$DEBUG" ]; then
        DEBUG=''
else
        DEBUG='echo '
fi

OFFSET=`LANG=C fdisk -lu ${FSIMG} | awk '/\.img2/ && /Linux/{print $2 * 512}'`

${DEBUG} mount -o loop,offset=${OFFSET} ${FSIMG} ${MOUNTPOINT}

${DEBUG} cp -f /usr/bin/qemu-arm-static ${MOUNTPOINT}/usr/bin/

${DEBUG} mv ${MOUNTPOINT}/usr/sbin/policy-rc.d ${MOUNTPOINT}/usr/sbin/policy-rc.d.save
${DEBUG} echo -e '#!/bin/sh\nexit 101' > ${MOUNTPOINT}/usr/sbin/policy-rc.d
${DEBUG} chmod +x ${MOUNTPOINT}/usr/sbin/policy-rc.d
${DEBUG} echo -e "${CHROOTNAME}-chroot" > ${MOUNTPOINT}/etc/debian_chroot

${DEBUG} mount -o rbind /dev ${MOUNTPOINT}/dev
${DEBUG} mount -t proc none ${MOUNTPOINT}/proc
${DEBUG} mount -o bind /sys ${MOUNTPOINT}/sys
${DEBUG} mount -o bind /tmp ${MOUNTPOINT}/tmp


# if [ ! -z "$DEBUG" ]; then
#        ${DEBUG} echo "':arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-arm-static:' > /proc/sys/fs/binfmt_misc/register"
# else
#         echo -e ':arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-arm-static:' > /proc/sys/fs/binfmt_misc/register
# fi

${DEBUG} chroot ${MOUNTPOINT} su - ${SUDO_USER}

${DEBUG} umount -fRl ${MOUNTPOINT}/dev
${DEBUG} umount ${MOUNTPOINT}/proc
${DEBUG} umount ${MOUNTPOINT}/sys
${DEBUG} umount ${MOUNTPOINT}/tmp
${DEBUG} mv -f ${MOUNTPOINT}/usr/sbin/policy-rc.d.save ${MOUNTPOINT}/usr/sbin/policy-rc.d
rm -f ${MOUNTPOINT}/etc/debian_chroot
${DEBUG} umount ${MOUNTPOINT}