a) Purpose of these scripts
----------------------------
These scripts are intended to run on a Soekris net5501-70 (512 MB RAM) embedded system
with a 4 GB Compact Flash (CF) as storage device.
Because NAND CF has "only" a write endurance of ~1,000,000 cycles per location, it
is a good idea to swap highly used parts of the OS to a ramdisk/tmpfs. In this case /var.
Like this we can increase the CF lifetime and mount i.e. the root partition in read only.
As a little gadget the soekris GPIO error LED is activated when a script error occurs.
- Fast blinking error LED means: Fatal error, please investigate.
- Slow blinking error LED means:
varbak.sh couldn't use tmpfs for data sync. It used CF instead. This is not good for the CF lifetime.
This is only a warning and will be deactivate automatically by varbak.sh as soon as it has enough free
RAM again to use a tmpfs.
Note: Tests here were made with an Ubuntu10.04 server 32Bit on a Soekris net5501-70 system.
b) How to use these scripts
---------------------------
1) The CF partition scheme must consist of these partitions:
/ #root tree partition, i.e. 3,5GB.
Mount options: noatime
/var #var partition, i.e. 200MB.
Mount options: nodev, nosuid, noatime
/varbak #varbak partition, i.e. 200MB. This is a helper partition for syncing data etc.
Mount options: nodev, nosuid, noatime, noexec
2) run "os-config.sh" once to prepare the OS for "var2rd.sh" and "varbak.sh", for
soekris serial console, ... (optional)
3) copy "error-led.sh" to /usr/local/sbin. This script is used by "var2rd.sh" and "varbak.sh"
4) copy "var2rd.sh" to /usr/local/sbin and use /etc/rc.local to use it as startup script.
Note: If you want to mount the root partition in read only, use rc.local. Otherwise
the script may disturb itself by accessing / while remounting / in read only.
5) copy "varbak.sh" to /usr/local/sbin and use it as cronjob and reboot/shutdown script
in order to save data from ramdisk/tmpfs back to CF.
Note: You need to place a symlink in /etc/rc0.d/ and /etc/rc6.d/ to use this script as
reboot/shutdown script. This is important because /sbin/init invokes the scripts
in /etc/rc[06].d/ with the "stop" argument. This argument is recognized by this
script in order to config itself.
c) Brief overview about the tasks that these scripts accomplish
---------------------------------------------------------------
os-config.sh
- set kernel parameters
- deactivate "multiverse" and "universe" repos to save ~60MB in /var/lib/apt/lists/
var2rd.sh
- check for errors (/var/err), else activate error LED and quit
- create logfile mount points for varbak.sh and itself
- mount logfile tmpfs
- create logfile
- check if /var and /varbak are partitions
- get list of processes which are accessing /var
- stop/kill those proccesses
- clean /var/cache
- create /varbak/{run,lock}
- sync /varbak/{run,lock} (CF) with /var/{run,lock} (tmpfs)
- unmount /var/{run,lock} (tmpfs)
- sync /varbak (CF) with /var (CF)
- if ramdisk /dev/ram0 is used, format it and turn its fsck on/off
- mount ramdisk/tmpfs on /var
- sync /var (ramdisk/tmpfs) with /varbak (CF)
- start processess again
- save tmpfs logfile to /var/log/var2rd.log
- unmount logfile tmpfs
- call error_led.sh to create error_led and gpio node
- turn on/off / fsck
varbak.sh
- check for errors (/var/err), else activate error LED and quit
- check if tmpfs logfile mount point exists
- mount logfile tmpfs
- create logfile
- check if /dev/ram0 or tmpfs is mounted on /var
- check if /var and /varbak are partitions
- get list of processes which are accessing /var
- stop/kill those proccesses
- if enough free RAM, use a tmpfs to sync data between /var (ramdisk/tmpfs) and /varbak (tmpfs)
if not enough free RAM, use /varbak (CF) to sync data
- clean /var/cache
- sync /varbak (CF/tmpfs) with /var (ramdisk/tmpfs)
- unmount /var (ramdisk/tmpfs)
- sync /var (CF) with /varbak (CF/tmpfs)
- mount ramdisk/tmpfs on /var again if needed
- start processess again if needed
- unmount logfile tmpfs
error-led.sh
- load GPIO kernel modules
- create error LED nod
- create GPIO nod
- de-/activate error LED
d) PXE installation of Ubuntu10.04 server 32Bit on Soekris net5501-70
---------------------------------------------------------------------
NOTE: The following steps where tested with a Ubuntu10.04 Desktop 32Bit system.
1) Serial connection to net5501
===============================
1.1) Install minicom:
> apt-get install minicom
1.2) Use these configurations for /etc/minicom/minirc.dfl:
------------------------------------
pu port /dev/ttyUSB0
pu baudrate 19200
pu bits 8
pu parity N
pu stopbits 1
pu rtscts No
pu zauto C
-------------------------------------
Note: - The default baud rate of the net5501 is: 19200
- Soekris doesn't support any kind of Flow Control.
- I used a USB to Serial adapter (/dev/ttyUSB). If you use a
COM slot adapt it to /dev/ttyS?
1.3) Connect to net5501:
> minicom
1.4) comBIOS update:
Note: Without an update it is probable that the comBIOS will not recognize newer Compact Flash cards.
Now that we have a connection, we want to update the comBIOS.
Download newest comBIOS: http://soekris.com/downloads.html
Look here for an update how to: http://wiki.soekris.info/Updating_Bios
As we have just configured "minicom", I recommend to use it here, too.
2) DHCP server
==============
2.1) Install DHCP server:
> apt-get install dhcp3-server
2.2) Config DHCP server:
2.2.1) Append the following lines to /etc/dhcp3/dhcpd.conf and adapt addresses to your needs:
----------------------------------------------
subnet 192.168.0.0 netmask 255.255.255.0 {
range 192.168.0.200 192.168.0.253;
option broadcast-address 192.168.0.255;
option routers 192.168.0.1;
option domain-name-servers 192.168.0.1;
}
host soekris {
# tftp client/soekris hardware address
hardware ethernet 00:00:24:??:??:??;
filename "pxelinux.0";
}
----------------------------------------------
2.2.2) Define your NIC in /etc/default/dhcp3-server
INTERFACES=eth?
2.3) Start dhcp server
> /etc/init.d/dhcp3-server start
3) TFTP server
==============
3.1) Install TFTP server:
> apt-get install tftpd-hpa
4) INETD server
===============
4.1) Install INETD server:
> apt-get install openbsd-inetd
4.2) Config INETD server:
Append this line to /etc/inetd.conf
------------------------------------------------------------------------------------------------------
tftp dgram udp wait root /usr/sbin/in.tftpd /usr/sbin/in.tftpd -s /var/lib/tftpboot
------------------------------------------------------------------------------------------------------
4.3) Start INETD server:
> /etc/init.d/openbsd-inetd start
5) netboot.tar.gz
=================
5.1) Download file:
> wget http://archive.ubuntu.com/ubuntu/dists/lucid/main/installer-i386/current/images/netboot/netboot.tar.gz
5.2) Extract file:
> tar xzfv netboot.tar.gz -C /var/lib/tftpboot/
5.3) Config installer:
5.3.1) var/lib/tftpboot/pxelinux.cfg must look like this:
-----------------------------------------------------------
CONSOLE 0
SERIAL 0 19200 0
include ubuntu-installer/i386/boot-screens/menu.cfg
default ubuntu-installer/i386/boot-screens/vesamenu.c32
prompt 0
timeout 0
-----------------------------------------------------------
5.3.2) /var/lib/tftpboot/ubuntu-installer/i386/boot-screens/text.cfg must look like this:
-----------------------------------------------------------------------------------------------------------
default install
label install
menu label ^Install
menu default
kernel ubuntu-installer/i386/linux
append tasks=server vga=normal initrd=ubuntu-installer/i386/initrd.gz -- console=ttyS0,19200 noplymouth
label cli
menu label ^Command-line install
kernel ubuntu-installer/i386/linux
append tasks=standard pkgsel/language-pack-patterns= pkgsel/install-language-support=false vga=normal initrd=ubuntu-installer/i386/initrd.gz -- console=ttyS0,19200
-----------------------------------------------------------------------------------------------------------
NOTE: - "tasks=server" in the "append" line tells the installer to install a Ubuntu server. Use "tasksel --list-tasks"
to get other options for tasks=...
- Dont't forget to append "console=ttyS0,19200"
- noplymouth turns of the grafical Boot Splash
6) Soekris and PXE
==================
Note: These 2 comBIOS parameters must be set as follows, otherwise the net5501 won't boot from PXE.
- PCIROMS = Enabled
- PXEBoot = Enabled
Note: Typ "show" in comBIOS prompt to see all comBIOS settings.
6.1) Boot from PXE:
> boot F0
Now, at the "boot:" prompt typ:
> install
That's the name of the "label" in /var/lib/tftpboot/ubuntu-installer/i386/boot-screens/text.cfg
Note: At the beginning of the installation it is likely that you won't see any output for a while (~ 10-15 min.).
But this will normally change and the system download will start.
Note: Don't forget to use the partition scheme mentioned above.
Note: After the installation the OS doesn't start automatically from CF.
To start it manually, typ:
> boot 80
Note: 80 = 1. dev.
This of course only works if the CF is the Primary Master device.
To verify that, watch the net5501 boot screen (Pri Mas):
-------------------------------------------------------------------------------
0512 Mbyte Memory CPU Geode LX 500 Mhz
Pri Mas SanDisk CompactFlash 200x LBA Xlt 971-128-63 3917 Mbyte
-------------------------------------------------------------------------------
AND in the comBIOS settings check this option by entering "show":
-------------------------------------------------------------------------------
FLASH = Primary
-------------------------------------------------------------------------------
- Workaround to let Soekris automatically boot from CF:
Set the following option after entering the comBIOS monitoring mode (press CTRL+P at boot time)
> set BootDrive=80 80 F0
Note: - 80 = 1. device
- 81 = 2. device
- F0 = PXE
Note: Default is: BootDrive=80 81 F0 FF
That's it.