PCI Express Throughput

x1 : 0.5GBps (4gbps)

x2 : 1GBps (8gbps)

x4 : 2GBps (16gbps)

x8 : 4GBps (32gbps)

x16: 8GBps (64gbps)

x32: 16GBps (128gbps)

Hacking ASUS WL520GU, Installing openWRT

Last week I tried to hack the Asus WL520GU wifi router, after reading this article - Building a Wifi Radio. Though you do not need to have a serial console to hack it, It makes all the sense to have one, just to know what is going on in your router. I bought some 0.1" male header on-line and soldered in the right place as shown in the mightyOhm article. I hit a road block when i found that i needed a serial driver to connect Asus Router to serial cable.

Router gives out 3.3V TTL signals. Whereas a RS232-serial port needs +/-12V signalling. If you connect a serial cable straight to router's header, it will not work. You need a chip to convert TTL level to RS232 level signals. The article mentioned about driver FTDI-232-3V3 which I could not find on-line in India. I tried this PC-MCU Serial Link (USB) converter, which is available on-line robokits.

This PC-MCU has a Female-header that does not work as signals order is different. You need to solder wires and 0.1" 4pin-female header as per the order given in the mightOhm article. Just leave the VCC pin as the driver chip gets power from USB. Connecting Gnd,Tx,Rx lines is enough to make it work. After you prepare the driver cable and connect to header and other end to USB of your laptop. Device Driver needs to be installed in order for the laptop to recognize the usb device as a serial COM port. After inserting the chord and driver, I get a new COM4 device to work with. I used Putty to connect -115200-8N1.

The mightyOhm article provides a Kamikaze build, Flashing procedure is straight forward. It was simple and trouble free to install kamikaze. Soon I realized that the kamikaze runs old 2.4 kernel. Sure enough, I had to upgrade to Backfire, which i did immediately.

miniHOWTO: Install FC14 in a Headless Server

I was trying to install a desktop centric Linux Distro like FC14 into a ATCA Blade based on intel. I and My co-worker tried to install as mentioned in my previous post.
FC14 did install but with minimal packages. It did not have basic utils like ftp. Need less to say, yum did not work. I let him work on it and crack it, which he did over a Sunday afternoon.

Following was his report:

--------------------

OS:- FC14x86_84

Mode of Installation:- Serial Console ( Using Minicom for installing ) and USB-DVD.

First boot the system using DVD drive and when the installation menu comes press Tab for editing the input commands. Then type,

linux console=tty0 console=ttyS0,115200n8 ( Enter)

After installation I assigned an IP and issued the command yum update I had to face to problem like yum was not working and I was getting the Error,

[root@localhost~]# yum update

Error Cannt retrieve repository Metadata ( respond.xml) for Repository:Fedora. Please verify its Path and try again.

Then I Google and found out some solution,

Problem was with the Python, it does not handle https proxy well. So I change all the https present in *.repo files in /etc/yum.repos.d/ to http

Here’s the way to do it… edit your repository files /etc/yum.repos.d/fedora.repo and /etc/yum.repos.d and /fedora-updates.repo by commenting all the lines starting with term mirrorlist and uncommenting all the lines starting with term baseurl.

After that my yum started working fine for me.

Referenece URL:-

http://rishabhsays.wordpress.com/2010/01/24/error-cannot-retrieve-repository-metadata-repomd-xml-for-repository-fedora/

--------------------
Thanks: S.Dhananjaya.

"ஜெ.சுயநலம் இல்லாதவர் " சாருவின் கருத்து

"ஜெயலலிதா சுயநலம் இல்லாதவர் என்றே நான் நினைக்கிறேன். கருணாநிதியின் குடும்பத்தில் சுமார் 500 பேர் இருப்பார்கள். தமிழகத்தின் அத்தனை துறைகளும் அவர்கள் கையில்தான் இருந்தன; இருக்கின்றன. ஜெயலலிதா ஒரே ஆள். உலகில் தனித்து வாழும் மனிதர்கள் சுயநலம் கருத வேண்டிய அவசியமே இல்லை." - சாரு நிவேதிதா

என்ன கொடுமை சார் இது?

HOWTO: Install centos 5.4 OR RHEL 5.5 over serial console

I had to install a processor blade which could boot from USB but it didnot have VGA & Keyboard. Serial port was the only option. I tried to do like this.

It did not work. Later I fugured, I do not need to modify the ISO. I could do it so easily. The procedure is roughly like below.

1) Insert your bootable DVD and connect your DVD-Drive to USB.

2) Make the BIOS boot from USB Drive.

3) Prepare your putty/minicom suitably. 115200-8-n-1 worked for me.

4) You will see following menu.

5) Select F4 to type in command line arguments to kernel.

6) Type in

boot:linux console=tty0 console=ttyS0,115200n8

7) press ENTER and you will see booting proceeding with logs showing in your console.

Happy Exploring.

Buying time?

The nifty trades around 5663 today, reflecting the P/E of sub 22. Analysis shows that the market had traded below 22 only on 30% of the days last year. So, based on 2010 data, the Nifty is correcting from expensive region.

Is it cheap enough at current levels? Are market headed further south? I do not know. But, I think it makes sense to start accumulating from these levels.

Packet Length Distribution in LAN - II

After running the experiment for about 10 days, the table looks like this...

Pkt Histogram
==============
Length %of total packets
=========================
0-63 21.28
64-127 0.69
128-191 5.43
192-255 0.83
256-319 0.56
320-383 0.03
384-447 0.04
448-511 0.06
512-575 0.07
576-639 0.07
640-703 0.05
704-767 0.05
768-831 0.05
832-895 0.03
896-959 0.04
960-1023 0.03
1024-1087 0.03
1088-1151 0.04
1152-1215 0.04
1216-1279 0.1
1280-1343 0.02
1344-1407 1.42
1408-1471 0.02
1472-1535 69.01