Thursday, May 20, 2010

Developing your bootloader

Google group

Hello world bootloader

Wednesday, May 19, 2010

Tun/TAP networking with QEMU

Saturday, May 15, 2010

Pxe boot installation for Ubuntu

On many blogs on internet it says
"If you have the cd or cd image mounted in /var/www/ubuntu, then you will have material for netboot here: /var/www/ubuntu/install/netboot/"

but that is not the case
That is exactly where the problem is the instead it has a directory named casper where it has initrd and vmlinuz some where I read for this I need a Live CD of Ubuntu
in the install directory I have following only
root@tapas-laptop:/mnt/install# ls
mt86plus README.sbm sbm.bin

Just check the following link I downloaded netboot from Ubuntu Jaunty repositories from here
they have an image named mini.iso

Finally I found a solution the CDs named alternate have the netboot folder this is what is needed.

TFTp settings on Ubuntu I forgot but had discussed some thing here

I kept in /var/lib/tftpboot the files related to installtion
the TFTP settings for booting via network
Following changes were made to config files

First file
tftp dgram udp wait root /usr/sbin/in.tftpd /usr/sbin/in.tftpd -s /var/lib/tftpboot
## netbios-ssn stream tcp nowait root /usr/sbin/tcpd /usr/sbin/smbd

Second file
OPTIONS="--tftpd-timeout 300 --retry-timeout 5 --mcast-port 1758 --mcast-addr --mcast-ttl 1 --maxthread 100 --verbose=5 /var/lib/tftpboot"

Third file

#Defaults for tftpd-hpa
OPTIONS="-l -s /var/lib/tftpboot"

Fourth file I touched was

# Default settings for xinetd. This file is sourced by /bin/sh from
# /etc/init.d/xinetd

# enable xinetd Inetd compat mode

# Options to pass to xinetd
# -stayalive comes by default : it can be removed if xinetd is expected
# not to start when no service is configured

Then 5th file
ddns-update-style none;
allow booting;
allow bootp;

option domain-name "";
#option domain-name-servers,;

option domain-name-servers;

default-lease-time 600;
max-lease-time 7200;
log-facility local7;

# No service will be given on this subnet, but declaring it helps the
# DHCP server to understand the network topology.

subnet netmask {

# A slightly different configuration for an internal subnet.
subnet netmask {

option domain-name-servers;
option domain-name "";
option routers;
option broadcast-address;
default-lease-time 600;
max-lease-time 7200;
filename "pxelinux.0";
option domain-name-servers;
option domain-name "";
option routers;
option broadcast-address;
default-lease-time 600;
max-lease-time 7200;
filename "pxelinux.0";

A good article explaining what DHCP entries are

bug in tasksel

data recovery linux

Data recovery from Linux

Tuesday, May 11, 2010

Some good links about Xen

Good link for Xen not for beginners

Following was a problem I faced

Python scripts for Xen

Ok type Linux Clustering 1 Linux Clustering 2
Linux Virtualization with Xen (Orielly Guide)

Zimbra guide

Novells Excellent Guide

Tracing system calls with Linux and implementing your system calls xen code documentation

Xen code documentation.

Monday, May 10, 2010

CentOS DomU on Debian
Discussion going on here

and here nothing came till now

Some one mentioned to do it

A relevant thread is

Another installation method which seems not to give error

xen-create-image --hostname=ocw --size=96GB --swap=2048 Mb --ip= --memory=1024 --arch=amd64 --role=udev --force --install-method=rinse --install-source=/root/inscd/
Most probably when you delete an existing VM and create a new with same name LVM shows that it is no more infact that is what is causing problems.So to my surprise change of name had worked.

Problem in configuring VNC

Now finally we are moving to QEMU vnc thing had failed
using QEMU and pygrub etc etc

These are snapshots of running QEMU

The installation was very slow so I had to finally kill because in 2 hours only 20% of it was installed some one suggested to use kqemu.

This article
did not worked for me.
Trying this one

Some snapshots of all the process.

Finally to be able to boot from QEMU on SSH
I did
qemu-system-x86_64  -hda /dev/virtualization/centos5-disk -hdb
/dev/virtualization/centos5-swap -m 1024 -boot c -net nic -net tap                 

A strange problem using QEMU

I am facing one more problem during the installation.If I press a key
once after some time I see the effect in QEMU screen there is some
delay and after this delay the effect of pressing the key is as if I
have clicked multiple times.Say
I have to enter the gateway address
If I press 9 or any of the above digit once
rather than typing
it types
199999999999999999 and then after some time it releases the cursor to
type any thing.
to choose between two menu
---> press cancel
 yes  no
If I choose yes it clicks many times automatically yes and goes back
to previous menu and then comes again to forward menu so back and
forth switching between menus.
Which makes it very difficult to move ahead it has been two hours but
I could not proceed at all with this.
More over the response is coming very slow if pressing any key stroke
from my laptop because of which I have to wait for a long time to get
the response and move to another menu.

I am not using the GUI based installer it is a text based install.If I
use a GUI  it is very very slow and have to wait for a very long time
for the response to come.
For example clicking on License agreement you agree yes
to do so it takes a very long time which it is not taking in text mode
but the above problem of seeing the effect multiple times in an
undesired way and slow response is there.
This is not a consistent situation but occurring at irregular
intervals.This has made my work very slow.
Is there any way to get rid of this?

Did this with KQEMU
After all the above experiments failed we finally moved to virsh

Now a nonsense blog made my work difficult.Later on problem was resolved.

Sunday, May 9, 2010

Kernel Development

Greg Kroah Hartman on Linux Plumbing

Screen cast
Got both above from here

Difference between initrd and initramfs
Some information can be searched here

Saturday, May 8, 2010

some blogs blah blah

Linux Administration books Available for free

Linux: Allow SSH Console Login But Not GDM / KDM / X Windows Based Login

Download of the day: GNU/Linux Advanced Administration PDF Book

NiXcraft PDF

Multiple X sessions

UniX Haters book

My name there

Teo En Min Xing Blog
How to setup your own Virtual Super Computer

Open Source project management softwares
Limit IPTABLES connection per limit


Useful for servers

A shell script for IPTABLES see later
Restrict Access to commands

find ~ -name \.\* -exec chmod go-w {} \;

hdparm: HDIO_DRIVE_CMD(identify) Failed: Inappropriate Ioctl For Device

Using Awk for Shell scripts

Arrrggg: Open Source Users Are Pirates

nixCraft FAQ PDF Collection Now Available To All

Open Source Project Management Softwares
Comparison of Project Management Softwares

Syslog tutorial

Perfect Desktop

WireShark Tutorial
Network Analysis with WireShark

Firewall Builder

Subversioning on Lenny

Load Balancing Cluster on CentOS

Install Multiple Distributions PXE

Setting Up a PXE server on Ubuntu

Friday, May 7, 2010

Beowulf Clusters,2

Xen Virtualization and Linux clustering

Gazab gyan

Thursday, May 6, 2010

Grail Geromino imp links

Web based Server controls

Ajax term for remote administration
Open SSH login tricks
Reverse SSH tunnels

Tuesday, May 4, 2010

Grails apache geronimo some problem in deploying debian

I want to deploy a web application that is made using grails.
By reading documentation I came that has to be converted to a .war format file.
This file has a deployment plan which comes in two XML files.

Right now I failed to deploy the application on the geronimo server.

I went through

Troubleshooting J2EE asset deployment

I did read all of the above links but I was not able to created xml
files to deploy them as specified.Upto this point I infer that the
problem is coming from deployment plan.

A solution that after came to mind to is create the website
using an IDE like Eclipse on a laptop or so and then that IDE will
take care of deployment plan which may have errors that I am right now
not able to find.

Then that application can be deployed on the server.Since I do not
have a GUI on server so it is not possible right now to do that way on

Here is a link to what I am saying.

Since the helloworld script war running successfully on grails server
so it comes to either the way deployment is done or the deployment
plan that refers to XML files.

using windows to deploy .war files

Check if some thing goes wrong

Creating a deployment plan for web applications

IBM technical library
also this one

Apache Geronimo on Grails

Geronimo deployment using Eclipse

Some relevant links for GRAILs

Tutorial from IBM about Grails

Grails1 tutorial

Grails 2 tutorials


Creating an Admin using Nested Controllers

Debian help to install Java

Websites that run Grails;jsessionid=67F5EAF0A52072F96007AECA75396A0C

Login sample;jsessionid=7FF929DC7F1495C094DE42402A299D3B

Grails tutorials

Difference between geronimo and tomcat

Deployment plan for xml files