Edits the the Nook Color initial ramdisk of Android 4.3-based ROMs (e.g. CyanogenMod 10.2) to mount the internal eMMC data partition to be used as an “SD card”. You need to run this script from an Unix system (e.g. GNU/Linux) with your device connected. The tools “adb” and “mkimage” (from u-Boot) must be installed.

encore-cm10.2-sdswap.sh

#! /bin/bash
#
# android-4.3-encore-sdswap-ramdisk
# Copyright (C) 2013 Adrian Perez <[email protected]>
#
# Distributed under terms of the MIT license.
#
set -e

devices=$(adb devices | sed -e 1d -e '/^[:space:]$/d')
if [[ -z ${devices} ]] ; then
    cat 1>&2 <<-EOF
    No devices connected. Make sure your Nook Color is connected and
    that ADB can access its contents.
EOF
    exit 1
fi

# Should be random enough as to not have clashes with other directories.
tempdir="sdswap-$(uuidgen)"

# Cleanup will be called on user interruption or end the of the script.
cleanup () {
    adb shell sync
    adb shell umount "/data/local/tmp/${tempdir}"
    adb shell rm -rf "/data/local/tmp/${tempdir}"
    cd /tmp
    rm -rf "/tmp/${tempdir}"
}
trap cleanup INT EXIT

# A local temporary directory is used to unpack and edit the ramdisk.
mkdir -p "/tmp/${tempdir}/scratch"
cd "/tmp/${tempdir}"

# Mount the /boot partition of the Nook in a temporary random directory.
adb shell mkdir "/data/local/tmp/${tempdir}"
adb shell mount -t vfat /dev/block/mmcblk0p1 "/data/local/tmp/${tempdir}"
adb pull "/data/local/tmp/${tempdir}/uRamdisk" .

cd scratch
dd if=../uRamdisk bs=64 skip=1 | gunzip -c | cpio -i

# Edit the fstab.encore file. Note that replacements are only made
# for the sdcard and emmc lines. The way the edit is done allows to
# run the command several times on the same file and always get the
# same result.
mv fstab.encore ..
sed -e '/voldmanaged=sdcard/y:sdcard1:sdcard0:' \
    -e '/voldmanaged=emmc/y:sdcard0:sdcard1:' \
    ../fstab.encore > fstab.encore
diff -u ../fstab.encore fstab.encore || true

# Re-pack the ramdisk. The old uRamdisk is deleted first to avoid
# including it in the new one.
find . -regex './.*' | cpio -o -H newc | gzip -9c > ../ramdisk.gz
cd ..
mkimage -A ARM -T RAMDisk -n Image -d ramdisk.gz uRamdisk.new

adb push uRamdisk.new "/data/local/tmp/${tempdir}/uRamdisk.new"
adb shell mv "/data/local/tmp/${tempdir}/uRamdisk.new" \
             "/data/local/tmp/${tempdir}/uRamdisk"

# NOTE: Cleanup is done on exit using the cleanup() function above