Sungju Kwon's Very Slow Life

Samsung GALAXY Tab

Sungju — Sat, 04 Sep 2010 01:30:23 +0000

Could Samsung’s Galaxy Tab compete with iPad?

Unclear future

Sungju — Wed, 01 Sep 2010 00:13:59 +0000

Not like my own title ‘Very slow life’, my life goes in very rapid speed recently. That makes me a bit frighten because I didn’t prepared it well.

When I look back my recent couple of years, I seemed to have very busy life – in my opinion, but, I just realized that I didn’t achieved any significant result. In the near future, I have to decide my direction for future and for that, I would be need to prove my qualification or at least has a level of qualification for myself or others.

I’m going to have an another medical checkup today and I hope it goes well. If it goes wrong, I would be really frustrated. I’ll make a plan anyhow after today, though.

[BASH] Check dropped RX packets

Sungju — Mon, 02 Aug 2010 02:19:01 +0000

This is a simple bash script to check whether NIC is dropping packets or not. It works with only one NIC card at one time because there’s possiblity that packet can go through another NIC.

#!/bin/bash
 
NET_ON_LIST=`ifconfig | grep "Link encap:Ethernet"`
 
NET_ON_COUNT=`echo "$NET_ON_LIST" | wc -l`
if (($NET_ON_COUNT != 1)); then
        echo "Need to set only one active ethernet connection."
        echo "This system currently has" $NET_ON_COUNT "connections in ON status"
        exit 1
fi
 
rm -rf result.txt
echo "Checking started at " `date` | tee -a result.txt
echo "" | tee -a result.txt
 
trap 'echo "Checking ended at " `date` | tee -a result.txt' EXIT
 
NET_DEV=`echo $NET_ON_LIST | awk '{print $1}'`
RX_OK_PREV_COUNT=`ifconfig $NET_DEV | grep "RX packets" | awk '{ print $2}' | awk -F: '{print $2}'`
while [ 1 ]
do
        sleep 1.1
        RX_OK_COUNT=`ifconfig $NET_DEV | grep "RX packets" | awk '{ print $2}' | awk -F: '{print $2}'`
        if (($RX_OK_PREV_COUNT == $RX_OK_COUNT)); then
                echo "Value not changed for a second with value " $RX_OK_PREV_COUNT | tee -a result.txt
                echo "    at time " `date` | tee -a result.txt
                ifconfig $NET_DEV | tee -a result.txt
        fi
        RX_OK_PREV_COUNT=$RX_OK_COUNT
done

And a script for ping command.

#!/bin/bash
 
PING_SITE=$1
[ -z $PING_SITE ] && PING_SITE="google.com"
 
rm -rf send_data.txt
ping $PING_SITE | awk '/^[0-9]+ bytes from / { "date" | getline d; close("date -R") ; print d, ": ", $0; }'

Simple recipe to build your own LXRed Linux Kernel Source in Fedora 13

Sungju — Wed, 21 Jul 2010 12:03:41 +0000

$ yum install git inkscape postgresql postgresql-server texlive ctags perl-CGI-Ajax perl-CGI-Simple perl-DBD-Pg perl-HTML-Parser perl-Template-Toolkit perl-Term-ProgressBar.noarch perl-Term-Size perl-TermReadKey perl-Devel-Size gcc gcc-c++ texlive-utils texlive-latex perl-ExtUtils-MakeMaker perl-CPAN perl-YAML libpng libpng-devel texinfo perl-Digest-SHA1 wget http make icoutils xapian-core perl-Search-Xapian perl-CPAN perl-Search-Xapian gifsicle

$ cd /tmp && wget http://www.ctan.org/get/fonts/bbding/bbding.ins http://www.ctan.org/get/fonts/bbding/bbding.dtx

$ cpan $ cpan -fi Search::Xapian

$ mkdir /opt; cd /opt $ git clone git://lxr.linux.no/git/lxrng.git $ cd lxrng $ cp lxrng.conf-dist lxrng.conf $ cp apache2-site.conf-dist-cgi apache2-site.conf $ chkconfig httpd on $ chkconfig postgresql on $ service postgresql initdb $ service postgresql start

$ iptables -I INPUT 1 -p tcp --dport 80 -j ACCEPT $ iptables -I INPUT 1 -p tcp --dport 5432 -j ACCEPT $ service iptables save

$ cd /tmp $ cp /usr/share/texmf/fonts/tfm/public/niceframe/bbding10.tfm . $ tex bbding.ins $ mkdir /usr/share/texmf/tex/latex/bbding $ mv bbding.sty /usr/share/texmf/tex/latex/bbding/. $ texhash $ fmtutil-sys --all

$ set -i 's/ident sameuser/password/' /var/lib/pgsql/data/pg_hba.conf

$ su - postgres

-bash-4.1$ createuser -P lxr Enter password for new role: Enter it again: Shall the new role be a superuser? (y/n) n Shall the new role be allowed to create databases? (y/n) n Shall the new role be allowed to create more new roles? (y/n) n -bash-4.1$ createuser -P lxradmin Enter password for new role: Enter it again: Shall the new role be a superuser? (y/n) n Shall the new role be allowed to create databases? (y/n) y Shall the new role be allowed to create more new roles? (y/n) n -bash-4.1$ createuser -P apache Enter password for new role: Enter it again: Shall the new role be a superuser? (y/n) n Shall the new role be allowed to create databases? (y/n) n Shall the new role be allowed to create more new roles? (y/n) n -bash-4.1$ -bash-4.1$ createdb lxrng -O lxr -bash-4.1$ exit

$ service postgresql restart

$ mkdir /var/lib/lxrng/text-db -p $ mkdir /var/lib/lxrng/cache $ chmod a+rw /var/lib/lxrng $ chmod a+rw /var/lib/lxrng/cache/

$ make -C /opt/lxrng/webroot/.static/gfx $ mkdir -p /var/lib/lxrng/repos/ $ cd /var/lib/lxrng/repos/ $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git $ cd linux-2.6/ $ git tag

$ cd /opt/lxrng/ $ sed -i 's:@@LXRURL@@::' apache2-site.conf $ sed -i 's:@@LXRROOT@@:/opt/lxrng:' apache2-site.conf $ vi apache2-site.conf

... # For LXRng installed directly in the web site root, use ScriptAlias / "/opt/lxrng/webroot/lxr.cgi/" # otherwise use (no trailing slash): # ScriptAlias / "/opt/lxrng/webroot/lxr.cgi" ...

$ vi lxrng.conf

... 'base_url' => 'http://localhost/', ... 'ver_default' => 'v2.6.34', ...

$ ./lxr-db-admin linux --init

$ ln -s /opt/lxrng/apache2-site.conf /etc/httpd/conf.d/.

$ service httpd restart $ setenforce 0 $ ./lxr-genxref linux

If you are willing to database for a downloaded source, change following stuff in lxrng.conf

use LXRng::Repo::Plain;

my $plainrepo = LXRng::Repo::Plain ->new('Source Path');

ver_list => ['Project Name'], ver_default => 'Project Name',

Possible lxrng.conf example with two applications.

# -*- mode: perl -*-
# Configuration file
#
# 
 
use LXRng::Index::PgBatch;
use LXRng::Repo::Git;
use LXRng::Search::Xapian;
use LXRng::Repo::Plain;
 
my $linuxindex   = LXRng::Index::PgBatch->new(db_spec => 'dbname=lxrng;port=5432', 
					 db_user => "", db_pass => "",
					 # table_prefix => 'lxr'
					 );
 
my $linuxrepo = LXRng::Repo::Git
    ->new('/var/lib/lxrng/repos/linux-2.6/.git',
	  release_re => qr/^v[^-]*$/,
	  author_timestamp => 0);
 
my $linuxsearch  = LXRng::Search::Xapian->new('/var/lib/lxrng/text-db/linux-2.6');
 
my $rhevindex   = LXRng::Index::PgBatch->new(db_spec => 'dbname=rhev;port=5432', 
					 db_user => "", db_pass => "",
					 # table_prefix => 'lxr'
					 );
my $rhevrepo = LXRng::Repo::Plain->new('/var/lib/lxrng/repos/rhev');
 
my $rhevsearch  = LXRng::Search::Xapian->new('/var/lib/lxrng/text-db/rhev');
 
 
return {
    'linux' => {
	'repository'  => $linuxrepo,
	'index'       => $linuxindex,
	'search'      => $linuxsearch,
 
	'base_url'    => 'http://localhost/',
	# Must be writable by httpd user:
	'cache'	      => '/var/lib/lxrng/cache/linux',
 
	'fs_charset'  => 'iso-8859-1',
	# Tried successively
	'content_charset' => ['utf-8', 'iso-8859-1'],
 
	'languages'   => ['C', 'GnuAsm', 'Kconfig'],
	'ctags_flags' => ["-I\@$LXRng::ROOT/lxr-ctags-quirks"],
	'ver_list'    => [$linuxrepo->allversions],
 
	'ver_default' => 'v2.6.34',
 
	'include_maps' => 
	    [
	     [qr|^arch/(.*?)/|, qr|^asm/(.*)|,
	      sub { "include/asm-$_[0]/$_[1]" }],
	     [qr|^include/asm-(.*?)/|, qr|^asm/(.*)|,
	      sub { "include/asm-$_[0]/$_[1]" }],
	     [qr|^|, qr|^asm/(.*)|,
	      sub { map { "include/asm-$_/$_[0]" }
		    qw(i386 alpha arm ia64 m68k mips mips64),
		    qw(ppc s390 sh sparc sparc64 x86_64) }],
	     [qr|^|, qr|(.*)|,
	      sub { "include/$_[0]" }],
	     ],
    },
 
    'rhev' => {
	'repository'  => $rhevrepo,
	'index'       => $rhevindex,
	'search'      => $rhevsearch,
 
	'base_url'    => 'http://localhost/',
	# Must be writable by httpd user:
	'cache'	      => '/var/lib/lxrng/cache/rhev',
 
	'fs_charset'  => 'iso-8859-1',
	# Tried successively
	'content_charset' => ['utf-8', 'iso-8859-1'],
 
	'languages'   => ['C', 'GnuAsm', 'Kconfig', 'Generic' ],
	'ctags_flags' => ["-I\@$LXRng::ROOT/lxr-ctags-quirks"],
	'ver_list'    => [$rhevrepo->allversions],
 
#	'ver_default' => 'rhev',
 
    },
 
};

I’m still suffering to make it to show hyperlink lists shows up. I guess it’s because it failed to execute ‘ctags-exuberant’ because I saw lots of messages regarding that as is shown below.

Can’t execute “ctags-exuberant”: No such file or directory at ./lxr-genxref line 191.”

Considering development kits

Sungju — Mon, 19 Jul 2010 01:43:47 +0000

Recently, I thought myself as an engineer which is insane. To overcome this situation and to do what I tried in my whole life, I decided to develop some code whatever it is.

One problem with this is what environment can be good for this. Just vi and gnu tools combination can work but I want more efficient method.

For the development method, I consider three possible volunteers – Eclipse, XCode, Qt Creator.

Eclipse (http://www.eclipse.org) is a best way if I want to develop Java-based application. You can use C/C++ and other languages as well. But, it seems a little bit heavier compare to others.

XCode is a good choice for Mac-oriented development. It provides full-featured environment with free of charge. One bad thing is that I only can use this in Mac and for Mac.

Qt Creator can be another possible choice. It provides a tool for Qt-based development. It has editor in it and debugger and others. Even it has GUI designer. It can be a good choice for multi platform application.

I still can’t choose one but will decide in near future before I start a project.

Only you – AB Avenue

Sungju — Sun, 04 Jul 2010 02:30:05 +0000

Ad songs that make feel good

Sungju — Wed, 23 Jun 2010 23:24:24 +0000

CF songs from insurance company, but it makes me feel good.

A song

Sungju — Fri, 18 Jun 2010 03:19:33 +0000

Linux Wireless Configuration Module – cfg80211

Sungju — Thu, 10 Jun 2010 02:47:01 +0000

If you travel frequently and have to access wireless internet in that country, you’d be better to check this article. Sometimes, in foreign country, you would face with unaccessible wireless AP.

One of the possible reason is that you use the different country code which is described in IEEE 802.11 regulatory domain code? from the code in that country use. Depends on this country code, it will choose proper frequency ranges

In Linux box, you can change this by cfg80211 module. Following is the information of cfg80211 module.

[root@dhcp-160-193 ~]# modinfo cfg80211
filename: /lib/modules/2.6.18-194.el5/kernel/net/wireless/cfg80211.ko
description: wireless configuration support
license: GPL
author: Johannes Berg
srcversion: 5575C55ADCFBE1371A2CF5E
depends: rfkill,wireless_compat
vermagic: 2.6.18-194.el5 SMP mod_unload gcc-4.1
parm: ieee80211_regdom:IEEE 802.11 regulatory domain code (charp)
module_sig: 883f3504ba0377778ccfeaa942826a…

You can find more information about cfg80211 in here: http://wireless.kernel.org/en/developers/Documentation/cfg80211#About_cfg80211?

If you are in Korea, you can change the region code by modify /etc/modprobe.conf

options cfg80211 ieee80211_regdom=KR

You can see the details of changing frequency in /var/log/messages such as following:

cfg80211: Calling CRDA to update world regulatory domain
cfg80211: World regulatory domain updated:
        (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
        (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
        (2457000 KHz - 2482000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
        (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
        (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
        (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
cfg80211: Calling CRDA for country: KR
cfg80211: Regulatory domain changed to country: KR
        (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
        (2402000 KHz - 2482000 KHz @ 20000 KHz), (N/A, 2000 mBm)
        (5170000 KHz - 5250000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
        (5250000 KHz - 5330000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
        (5490000 KHz - 5630000 KHz @ 20000 KHz), (300 mBi, 3000 mBm)
        (5735000 KHz - 5815000 KHz @ 20000 KHz), (300 mBi, 3000 mBm)

It will make you can access the AP’s in the country you stay.

Comment: Just realized that it works for EU and JP. Also, NIC needs to be have capability for that frequencies which you are want to use.

You and I

Sungju — Wed, 09 Jun 2010 06:56:23 +0000