post_install() {
    # get uboot wifi macaddr 
    tmpfile=$(mktemp -p /tmp)
    echo '/dev/mmcblk1   0x27400000   0x10000' > $tmpfile
    mac_wifi=$(fw_printenv -c $tmpfile mac_wifi)
    rm $tmpfile
    mac=${mac_wifi#*=}
    # make sure we have got a correct mac address
    if ! grep -qiE '([0-9a-f][0-9a-f]:){5}[0-9a-f][0-9a-f]' <<< "$mac"; then
        # oops! Then we might generate a random one
        mac=$(sed 's/^.*\(..\)\(..\)\(..\)\(..\)\(..\)\(..\)$/\1:\2:\3:\4:\5:\6/' < /etc/machine-id)
        grep -qiE '([0-9a-f][0-9a-f]:){5}[0-9a-f][0-9a-f]' <<< "$mac" || exit 1
    fi
    sed -i "s/^macaddr=.*$/macaddr=${mac}/g" /usr/lib/firmware/brcm/brcmfmac43455-sdio.phicomm,n1.txt
}

post_upgrade() {
    post_install $1
}