OpenWrt Forum Archive

Post #1

maddes.b

23 May 2009, 23:17

I want to use an USB-Stick (~4GB) for all the packages and programs on my router (USB 2.0 on LinkSys WRT350N v2, = Target Marvell Orion).
Due to being a Linux beginner I don't have the right idea how to do it correctly or how to start.
Therefore I need your help, ideas, whatever...

Config and main functionality (LAN, WLAN, DHCP, DNS, NPD, SSH, OpenVPN, DynDNS) should reside in Flash (squash/jffs), while others (Luci full, FTP, Samba) should be on the USB-Stick.
Goal is to have a running router without USB, and enhanced functionality with USB stick plugged in.

How to use SquashFS, JFFS and USB/EXT3 as overlays without hassle?
Which packages to include in Kernel image and/or JFFS? (general and router specific)
Start without USB first, do all the setup, then setup USB and additional functionality? Or is there a better way to do it?
Are there other similar setups useful?

Kind regards
Maddes

(Last edited by maddes.b on 23 May 2009, 23:47)

Post #2

Mavy

8 Jul 2009, 08:12

I have actually done this by using the pivot_root command. Basically you start the router from flash and once usb is loaded it will switch to a rootfs on the USB drive.

The script i used would check if the USB device existed and if it is boot-able. This means that if there is no usb drive the router will still boot with basic functionality.

Once i get back home i will reconnect my wrt350 and see if i can still find the scripts i used for it.

EDIT: I used the preinit script in this post as a starting point. http://forum.openwrt.org/viewtopic.php?pid=63032#p63032

(Last edited by Mavy on 8 Jul 2009, 08:38)

Post #3

Mavy

9 Jul 2009, 09:40

This is the preinit i have used to switch to the root on the usb stick

#!/bin/sh
# Copyright (C) 2006 OpenWrt.org
export PATH=/bin:/sbin:/usr/bin:/usr/sbin
. /etc/diag.sh

failsafe_ip() {
    ifconfig $ifname 192.168.1.1 netmask 255.255.255.0 broadcast 192.168.1.255 up
}

failsafe() {
    [ -n "$ifname" ] && grep "$ifname" /proc/net/dev >/dev/null && {
        failsafe_ip
        netmsg 192.168.1.255 "Entering Failsafe!"
        telnetd -l /bin/login.sh <> /dev/null 2>&1
    }
    lock /tmp/.failsafe
    ash --login
}

mount_usb() {
        boot_dev="/dev/sda2"
        mount_point="/mnt"

        echo "# Loading modules for usb"
        insmod usbcore
        insmod ehci-hcd
        insmod scsi_mod
        insmod sd_mod
        insmod jbd
        insmod ext2
        insmod ext3
        insmod usb-storage

        echo "# Waiting for devices to come up"
        sleep 10

        [ -e $boot_dev ] || {
          echo "$boot_dev NOT found"
          return 1
        }
        echo "# $boot_dev found"

        mount -o rw $boot_dev $mount_point || {
          echo "mount $boot_dev $mount_point failed"
          return 1
        }
        echo "# $boot_dev mounted on $mount_point"

        [ -e $mount_point/usb.boot ] || {
          echo "Missing file /usb.boot on media - NOT bootable, umounting."
          umount $mount_point
          return 1
        }
        echo "# Medium seems to be bootable"

        mount -o move /proc $mount_point/proc && \
          pivot_root $mount_point $mount_point/rom && {
            mount -o move /rom/dev /dev
            mount -o move /rom/sys /sys
            mount -o move /rom/tmp /tmp
          }
        echo "# Changed root to USB medium"

        return 0
}

mount proc /proc -t proc
mount sysfs /sys -t sysfs

size=$(awk '/MemTotal:/ {l=5242880;mt=($2*1024);print((s=mt/2)<l)&&(mt>l)?mt-l:s}' /proc/meminfo)
mount tmpfs /tmp -t tmpfs -o size=$size,nosuid,nodev,mode=1777

if grep devfs /proc/filesystems > /dev/null; then
    mount devfs /dev -t devfs
    M0=/dev/pty/m0
    M1=/dev/pty/m1
    HOTPLUG=/sbin/hotplug-call

elif [ -x /sbin/hotplug2 ]; then
    mount -t tmpfs tmpfs /dev -o size=512K
    mknod /dev/console c 5 1
    /sbin/hotplug2 --set-worker /lib/hotplug2/worker_fork.so --set-rules-file /etc/hotplug2-init.rules --no-persistent --set-coldplug-cmd /sbin/udevtrigger
    /sbin/hotplug2 --set-worker /lib/hotplug2/worker_fork.so --set-rules-file /etc/hotplug2-init.rules --persistent &
    M0=/dev/ptmx
    M1=/dev/ptmx
    HOTPLUG=

elif [ -x /sbin/udevd ]; then
    mount -n -t tmpfs -o mode=0755 udev /dev
    /sbin/udevd --daemon
    /sbin/udevtrigger
    /sbin/udevsettle
    M0=/dev/pty/ptmx
    M1=/dev/pty/ptmx
    HOTPLUG=
fi

mkdir -p /dev/pts /dev/shm
mount devpts /dev/pts -t devpts

# the shell really doesn't like having stdin/out closed
# that's why we use /dev/pty/m0 and m1 as replacement
# for /dev/console if there's no serial console available
dd if=/dev/console of=/dev/null bs=1 count=0 >/dev/null 2>/dev/null && {
    M0=/dev/console
    M1=/dev/console
}

exec <$M0 >$M1 2>&0

echo "- preinit -"
echo "Press CTRL-C for failsafe"
trap 'FAILSAFE=true' INT
trap 'FAILSAFE=true' USR1
[ -e /etc/preinit.arch ] && . /etc/preinit.arch
set_state preinit
echo "$HOTPLUG" > /proc/sys/kernel/hotplug
export FAILSAFE
eval ${FAILSAFE:+failsafe}
lock -w /tmp/.failsafe

if [ -z "$INITRAMFS" ]; then
    mount_usb || mount_root
    [ -f /sysupgrade.tgz ] && {
        echo "- config restore -"
        cd /
        mv sysupgrade.tgz /tmp
        tar xzf /tmp/sysupgrade.tgz
        rm -f /tmp/sysupgrade.tgz
        sync
    }

    echo "- init -"
    
    exec /sbin/init
fi

It requires a ext2 or ext3 partition on a usb stick.
I used the tgz file which contains the rootfs and extracted it to the usb stick.
I then had to manually create the /rom folder on the usb stick aswell as the /rom/dev, /rom/sys and /rom/tmp folders.

To boot from the usb stick create a empty file called usb.boot in the root of the usb stick and your good to go.