Compiling a single module for the 2.6 Kernel

This is relatively straight forward. I just recently installed a new network card to play around with and to see if I can make head or tail of the driver details so I need to make sure I have the driver for the card.
I installed a NetGear F311, I had a couple of spares. The driver for this card is the natsemi driver. To see if you have the source try the following.
]$ locate natsemi
/usr/src/kernel-source-2.6.5/drivers/net/natsemi.c
/usr/src/kernel-source-2.6.5/include/config/natsemi.h
There is no need to be the root user for any of this until you need to actually install the driver, I will tell you when 😉
Copy both these files to a directory of your choice. Then, in the same directory create a Makefile with the following text:
1 obj-m := natsemi.o
2
3 KDIR := /lib/modules/$(shell uname -r)/build
4 PWD := $(shell pwd)
5
6 default:
7 $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
save it and then execute the folloing command:
]$ make
Some text should whizz past detailing what it is doing. In the directory which you ran make in there should now be several new files
natsemi.ko
natsemi.mod.c
natsemi.mod.o
natsemi.o
The one you are interested in is “natsemi.ko”. As the root user change to the directory containing the “natsemi.ko” file and run
]$ insmod natsemi.ko
If all goes well there should be no messages. To see if it loaded and to satisfy your curiosity try
]$ lsmod
natsemi 18976 0
tulip 36640 0
crc32 3840 2 natsemi,tulip
af_packet 12552 4
The above is what I have on mine
To see if the card works (Debian) edit your
/etc/network/interfaces
file and add the following. Note that I already have a card installed using eth0 so I have chosen eth1 for this card
11 iface eth1 inet static
12 address 192.168.1.10
13 netmask 255.255.255.0
Then issue the command
]$ ifup eth1
]$ ping 192.168.1.10
and you should now have the card working.

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Google Talk

I received an invite the other day to a Google talk in London. For those that don’t know me I am fascinated by search engines, particularly google since there is more online about how they did their stuff than any of the others. You can imagine my enthusiasm at the prospect of going so I registered my interest and decided to go.
I then discovered that the talk has been organized by Pulse Group. From what I can gather they are the recruitment arm of Google for Ireland (wild guess). This rang recruitment company alarm bells for me, (I wrote an entire site to circumvent the need to go through a recruitment company, I don’t trust them.)
I am making bets online that it is going to be some corporate nonsense recruitment drive with more emphasis on that than on Googles tech.
I was also disappointed by the website.
1. No document type
2. It is mostly flash so a lot of people cannot see it.
3. Most of the menus are tiny and hard to read.
4. I was unable to resize the text.
5. The text is embedded in flash so it cannot be indexed by Google the people they are representing.
6. Some of the menus are mouse dependent (The mouse must hover over them to view the content)
Its another site designed by managers for managers. I suppose they have a different set of requirements than me.
Anyway I didn’t go. I would be interested in hearing from people who did go and what they thought of the talk………….
As a follow up I was correct. A friend of mine went and was quite pissed off because it was a total waste of his time.

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Ticketmaster

Is everywhere.
I just ordered 4 tickets for the Reduced Shakespeare company at the Criterion Theater ( all his plays in 2 hours, bloody fantastic, an hysterical, poignant political masterpiece 😉
Every box office I phoned in the search of a show was run by tickemaster. Is it too late to buy shares?

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Xterm vs Eterm

I have been using Eterm for some time now because enlightenment is my normal choice on Linux and I have never really needed anything else, however, I have noticed that on my machine at work I was getting some odd behavior when using ALT-TAB to switch between terminals so I decided to try xterm instead and I have to say I am very impressed with it.
It involves a little bit more work to set up but then most good things do. So far I have experienced no odd behavior and I think I might adopt xterm as my default terminal, it just seems more mature and competent than Eterm.
These are the setting I stared with in .Xdefaults
xterm*Background: black
xterm*Foreground: grey
xterm*VT100*geometry: 140×28+1+1
xterm*font: 9×15
xterm*scrollBar: False
xterm*JumpScroll: on
xterm*saveLines: 4096
. To load then use
shell]$ xrdb .Xdefaults

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Tuning a perl for a Postgres based search engine

I have a database of just over 11000 jobs and I need to run and indexer against it for the search engine to work. Just recently this has been getting slower and slower due to other things going on with the server so I decided to have a look at it tonight. The following was what I done and what I found:
Preliminaries.
All regex’s are pre-compiled prior to comparison using something like:
$dict{qr/\b\Q$keyword\E\b/} = $keyword;
Table Name Rows
key_word_search ==: 51641
rss_jobs ==: 179 (last nine hours worth)
Total checks == 9243739 (approx)
Methods:
0. Normal index with no tuning applied. This is what has been running
for the last few months.
1. For each job entry we are indexing check first to see if the job_id
and the keyword is already in the index. If yes go to the next record.
2. Use perls “index” function to pre-process the result and only try a
full regex if the string appears somewhere in one of the 3 RSS entries.
Results.
I was not going to try and second guess the result but I had a feeling
that M2 would be quicker. What I was suprised at is just how much
quicker. I imagine each method would see an improvement if more RAM was
given to Postgres especially M1 and M0 but I doubt either of them would
catch M1.
Also, the trigger that inserts the job actually carries out quite a
few checks to ensure the entry does not already exist so M1 is being
duplicated somewhat anyway and I am not about to relax the database checks/integrity to satisfy performance. Performance can normally be
cured using some other method as can be seen here.
Outer == No. Total Operations applied.
Inner == No. Left after filtering by Method
Matched == No. we matched and will be entered into database.
The inner rule is the method I have put in to filter the results before
I try a full regex match. The original indexer had no filter.
Method 0:
Outer == 9239317 In == 9239317 MATCH == 3009
real 8m23.868s
user 8m9.510s
sys 0m0.720s
Method 1:
Outer == 9239317 In == 14546 MATCH == 3009
real 1m30.897s
user 1m25.840s
sys 0m0.520s
As you can see here using the perls inbuilt “index” function I have
managed to narrow the actual operations considerably. We are relying on
the speed of the index compared to an actual regex match to gain the
speed here. I imageine they have almost literally used C’s
char *strstr(const char *s1, const char *s2);
or something simlar.
Method 2:
Outer == 105084 In == 99293 MATCH == 23
real 2m9.680s
user 0m16.840s
sys 0m5.090s
We can see here that this method is a lot slower. I actually stopped
this one early and it had only completed just over 1% of the total
operations required and it took 2 minutes. This was going to be slow
due to the amount of IO required ie 9 million possible calls to the
database and then a binary lookup on and index of just over 800k is not
going to be that fast at the best of times.
As an excercise and to satisfy my own curiosity I tried to put M1 first
and use M2 after it to see what would happen and the following was the
result.
Outer == 9239317 In == 14540 MATCH == 3009
real 1m42.974s
user 1m22.980s
sys 0m1.430s
We can see from this that calling out to the database is adding
overhead to the process.
Conclusion:
When we are using heavy regex intensive operations it pays to
pre-process using perls inbuilt “index” rather than relying on the
speed of the regex itself.

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Writing Linux Device Drivers

I lost my internet connection at the weekend and was at a bit of a loss as to what I could do so I decided to take a pop at writing a simple module for the Linux kernel. I have a copy of
Beginning Linux Programming
ISBN: 1861002971
Authors: Richard Stevens and Neil Matthew
Ed: 2nd
so I turned to the back of it and started my foray into the Kernel. Now you need to remember that I am not a C programmer by trade and turning to the back of this book was a keen reminder of just how rusty my C is getting, not that it was ever rust free.
Luckily for me I have another book that is considered the C bible ie K&R and it deserves its reputation, it is a classic and I would recommend any programmer regardless of language choice to have a flick through it. When I was looking at some odd construct that those pointy hats had invented I had a flick through K&R and soon sorted it out.
Anyway back to the kernel. I was quick to discover that writing a module for the 2.6 kernel is not quite as straight forward as copying from the book and trying to understand what was going on. Things have been changing and I was getting all sorts of weird (or at least to me) and wonderful errors when trying to compile the kernel.
I eventually started to have a read at the recent modules in the source for 2.6.5 which I am running on this box. I also have the source for a 2.4 kernel on here so I opened 2 character drivers and compared notes between them. This is where I started to notice things that had changed. I made the changes I thought where necessary and I managed to get most of the “Hello World” module compiling but I was still getting errors.
I had a hunt around and I found a reference to some new build procedures for 2.6.5 so off I went in search of kbuild documentation and found some more stuff that had changed in the kernel. Namely the build procedure. This part was actually harder than the C that I had been struggling with.
After much swearing (I hate Makefiles and adding some more sugar is a pain in the ass) I managed to get the module compiling and I was on my way.
After a days work I now had a module that, on load would say
“Hello World”
and on removal
“Goodbye World”
time well spent or not? I haven’t decided yet. I wonder how often changes like this take place in the kernel and how much porting takes place because of it.
Where to go from here. I asked a few friends who know more about this stuff than I do and I got mixed advice about continuing. Some of them think the kernel is a mess because they are always changing the driver API among other things. I cannot comment because my knowledge of the Linux kernel is limited to spelling it and I sometimes get that wrong.
I did get some useful pointers though. The following is the best book I have found so far for someone like me who is just starting out in the kernel.
Linux Device Drivers, 2nd Edition
It is written for the 2.4 kernel but has a wealth of information that is still valid today. I have started porting the scull drivers from this to the 2.6 kernel I am running and it is proving very interesting. I printed off chapter 2 and 3 yesterday and have have almost finished them (40 mins from Luton to London on the train each way helps). So far it seems to be moving along at a fair old pace, I am just hoping I can keep up.
I could have done with the following at the weekend. This tells me what I needed to know about moving from 2.4 to 2.6. I can see myself using this a lot in the next few weeks.
Driver Porting

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PhpMyLibrary

I had a look at Koha as an open source library system we might use at work and I promised I was going to look at phpmylibrary the next day. Well I didn’t have time but I did manage to look at it just recently and here is what I found.
First off it installed very easily which was nice. We got it up and running with some problems ie we had to turn Globals on and under PHP this is normally considered a no no. This rung alarm bells in my head but I continued on.
Next thing I noticed was the code. It might be because I am used to Perl but the code just looked messy. This is no reason to judge it so I had a look at the main feature ie loading and understanding MARC21.
I could have saved myself a lot of time if I had noticed that they only support USMARC. I left a message on one of their mailing lists asking about the possibility of using MAR21 but heard nothing. Which was another bad sign i.e. from what I can tell its not a very active project.
Next thing I will be looking at is CDS ISIS which is a suite of tools written by United Nations Educational, Scientific and Cultural Organization (UNESCO)

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Swoogle

It would appear that Swoogle is not being very polite to web servers. It seems to hit me from 2/4 times a second. I am probably going to ban it from UKlug because its just not very nice to hammer someones server as hard as that. At least Google is useful ie poeple find my site via google and it still manages to be polite about it. You would think that people doing research would be trying to be a bit more polite about what they are doing.
I have sent a couple of emails to the technical contacts and the the people running swoogle
If I don’t get a reply I will ban their entire subnet because they appear to be using different IP address’s to spider from.
130.85.95.109
130.85.95.23

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Do not cast your pearls in front of swine

I heard a great saying today.
“do not cast your pearls in front of swine”
This is so true. The context I had heard it is was in reference to people who would not accept Open Source as an alternative to proprietary systems ie you try and convince someone that there is a tool that will do the job and it is free but they insist on spending money on a closed system because free stuff can’t possibly be as good, or maybe thats what they know and they don’t want to change.
Don’t bother with them, let them spend their money and go use your time on someone who deserves and appreciates it. Unfortunately some people are like horses and require their blinkers in order to work otherwise they get spooked.
For those interested in where the saying comes from its the Bible. The original King James says.
“Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.”
(Matt. 7:6).

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Unique Ip address parser

Dean sent me the following to parse the logs and see how many unique ip address’s I was getting on a monthly basis.
grep ‘Nov/2004’ uk*.log | awk ‘{ print $1 }’ | sort | uniq | wc
I wrote the following in Perl which does the same thing but I think I prefer Deans
perl -ne ‘/^(.*?)\s/; $a{$1}++;} END{for (keys %a){$c++;print “$_ == $a{$_}\n”} print “$c\n”;’ ukl*ss.log
maybe we could
perl -ane ‘$a{$F[0]}++};END{for (keys %a){$c++;print “$_ == $a{$_}\n”} print “$c\n”;’ ukl*ss.log
or maybe even
perl -ane ‘$a{$F[0]}++} END{for(keys %a){$c++;} print “$c\n”;’ ukl*ss.log
Or we could just
perl -ane ‘$a{$F[0]}++;END{print keys(%a).”\n”;}’ ukl*ss.log
bollicks to this. I am also sure there is some clever one liner in Perl to do this but I hardly ever use them so I will leave it to the reader to beat it 😉

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