NAS-CC Boot Firmware

This is the NAS-CC boot firmware. This firmware is meant to replace the LinkSys stock firmware.

NAS-CC boot's firmware main functionality is to:

• Allow users to run a standard Desktop class distribution.

Actual end user functionality is provided by the installed distro.

The NAS-CC boot firmware makes use of an old Buildroot snapshot (2008-08-27). This is included with the source distribution.

Allthough, this firmware is quite old, it provides all the functionality needed for a basic boot environment.

Package Contents

This is the list of the top-level files

• binaries/ - Where the images are created
• br-XXXXX/ - Created from buildroot-YYYYMMDD.tar.bz2.
• buildroot-YYYYMMDD.tar.bz2 - Snapshot of buildroot.
• dl/ - Contains downloaded source files. Empty until you do your own firmware builds.
• docs/ - Misc documentation.
• extras/ - Extra packages added by NAS-CC to what is already available from buildroot.
• kernel-patches/ - Patches to the stock Linux kernel. They provide the NAS200 platform specifics.
• local/ - buildroot build profiles.
• nas200-misc.mk - Some additional customisations to the root image.
• patches/ - Patches made to buildroot.
• README.txt - this file.
• mk - Utility scripts.
• skel/ - skeleton directories. Used to pre-initialise root images.
• tools/ - Support utilities.
• version.txt - Versioning information

Building from source

Unpack the source tarball. Then enter:

$ ./mk

From the root directory of the unpacked source tarball.

Testing the build

For this you need a working qemu program. Enter:

./mk run boot

This will attempt to run your boot image from qemu.

By default it will qemu user level networking. This means that it will configure the network using DHCP and assign IP address 10.0.2.15. The host acts as the router and is given IP address 10.0.2.2. A virtual DNS servers is visible on 10.0.2.3.

Installing the BOOT Firmware

BEWARE doing this may brick your NAS200.

Essentially there are two ways of getting NAS-CC on your device. One is using the redboot upgrade utility and the other one is using the upgrade firmware option from the webpage.

The preferred method for upgrading under NAS-CC is by the redboot upgrade utility since NAS-CC does not provide its own method for doing firmware upgrades. That is, if after downgrading to NAS-CC you want to go back to a different firmware you will have to use redboot upgrade to do so.

To upgrade using NAS-CC this software distribution includes a script to put your NAS200 in upgrade mode and the upslug program that is used to flash the firmware.

upslug is a Linux tool. For Windows users, you may want to visit this web site.

Before beginning, you must compile the upslug executable. This can be found in the tools/upslug subdirectory. It is up to you to decide if you want to place upslug in your executable PATH.

These steps must be run as root user:

1. Make sure your NAS200 is off.
2. run the script swupgrade which can be found in the tools/upslug sub-directory.
3. Turn-on your NAS200.
4. The NAS200 should start blinking its power LED orange. Also at this point swupgrade should have printed the word Redboot> and return you to the shell prompt.
5. Run upslug with upslug -f -u firmware.bin. Replace firmware.bin with the name of your firmware file.
6. Follow the prompts.

You can use this procedure to install not only NAS-CC but any firmware that is compatible with the NAS200.

Using NAS-CC boot firmware

Installing the boot NAS-CC firmware image does not touch any of the attached discs. By default it will scan any attached storage devices, either internal SATA or external by USB, for boot scripts. If it finds any, it will try to boot from them.

You can break the boot process by pressing the two USB buttons in the back of your NAS200.

If it did not find any boot scripts or if you aborted the boot process (by pressing the USB buttons) it will drop into fail-safe mode. In fail-safe mode, you can only log-in to the system by using an attached serial console. However, pressing the two USB buttons will enable a telnetd daemon.

By default this provides a password-less telnet console on an IP address provided by DHCP or the default redboot IP address: 192.168.21.249 if DHCP is not available.

You can then to start using your NAS-CC by telnet'ing to it (either by the IP address provided by the DHCP server or 192.168.21.249 if DHCP is not functioning). This will give you a prompt where you can enter Linux commands. You can use this prompt to check if things are working. A basic set of disc management and network commands are available for you to set-up your NAS200.

Booting a distro

After your NAS200 has been flashed you need to create a distro USB key to boot from.

Refer to the distro specific instructions:

• CentOS

NAS-CC Boot modes

The NAS-CC will boot the /rc script when first starting as the init process. This script scans all attached storage devices (including USB ports) for bootable partitions. If it finds one or more bootable partitions it will proceed to boot them. If this fails (because the partitions were misconfigured or there were none) then it will drop to its fail-safe mode.

Determining if a partition is bootable is done by mounting it and checking if any of thes files are present:

kexec scripts

• nascc*.sh
• lnxboot*.sh

chroot scripts

• chroot*.sh

firmware scripts

• fwboot*.sh

misc scripts

• script*.sh

NAS-CC will look for these files in all these directories of a partition:

• /boot
• /etc
• / (root)
• /share
• /share/boot
• /share/etc
• /public
• /public/boot
• /public/etc

The directories beginning with /share should map to the Linksys DISK_1 shares. While the ones begining with /public to the PUBLIC DISK shares.

The * should be replaced with a number which is used to determine the priority. i.e. higher priority scripts will override lower priority scripts. The default (if no number is specified) is 50.

So you can set up a bootable partition on the internal SATA discs with priority 50 and if you want to boot a differrent configuration you can store it on a USB drive with a higher priority. NAS-CC will boot from the USB drive if it has the highest priority. This is a way to quickly test new kernel/root configurations without having to reflash your device.

oneshot scripts

If the filename started with the characters one, the scripts is taken to be a oneshot script. That means, that it will only be used once and afterwards, the script will be renamed to no(original-name).

This is used so that you can safely test new boot configurations. If the boot configuration failed, it will be ignored the next reboot. You just need to rename the boot script to something without the no and/or one in front to make the change permanent. After you are happy that things work correctly.

kexec scripts

kexec scripts allows you to replace the currently running Linux kernel to a new kernel. kexec scripts can contain the following specifications:

kernel=vmlinuz
cmdline="console=ttyS0"
initrd=""

Shown are the default values. You can (should) override this as necessary. The kernel and initrd can be specified as absolute paths if starting with / or are considered relative to the kexec script location.

• kexec - THis is the name of the linux kernel we are trying to boot.
• cmdline - additional command line parameters that should be passed to the linux kernel command line (usually the append line in lilo).
• initrd - initrd file to use. If blank, no initrd will be used.

The kexec script file is actually a shell script so any shell commands are valid here.

Useful variables that are available for use are:

• bootpart - /dev/xxxyy device file path for the boot partition.
• bootdisc - /dev/xxx device file path for the boot disc (without partition).

chroot scripts

These scripts simply transfer control to the boot partition without loading a new linux kernel. This means that you will be using the Linux kernel loaded from flash. The boot partition will become the new root parition. chroot scripts can contain the following:

new_root=/mnt
old_root=/pivot
init=/sbin/init

These are the defaults and do not need to be specified.

The old root parititon will be available in the directory specified by old_root (/pivot by default) and must already exist on the root of the boot partition. The old root partition can then be unmounted.

Control will be transferred to the init program (usually /sbin/init) for the actual start-up sequence.

The boot parition is always mounted read-only.

firmware scripts

These scripts allow you to replace the currently running Linux kernel with a new kernel and initrd image loaded from a firmware image file, in the same format as the ones used to flash the system.

Firmware scripts can contain the following specifications:

cmdline="console=ttyS0 root=/dev/ram0"
fwname=linux.bin

Like kexec scripts, this file is actually a shell script so any shell commands are valid here.

Useful variables that are available for use are:

• bootpart - /dev/xxxyy device file path for the boot partition.
• bootdisc - /dev/xxx device file path for the boot disc (without partition).

This actually loads the squashfs into memory so you loose about 6MB of RAM with this set-up. Because the Linksys firmware will activate swap areas, this should not be much of a problem.

You can use this to boot the NAS200 original Linksys firmware. Just make sure that the boot script and firmware file are located either in a root share called /etc or /boot.

misc scripts

misc scripts are just shell scripts that will be called during the boot process.

These can be used to do special configuration actions on your device. Combined with the oneshot facility, this can be used for making unattended/scripted upgrades of devices.

See Also

Further information can be found in the sources doc directory here.

Copyright

NAS-CC is Copyright (C) 2008 Alejandro Liu Ly

NAS-CC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

NAS-CC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public icense along with this program. If not, see http://www.gnu.org/licenses/