This week has been a little hectic, as I've been struggling with testing different versions of the
Specifically I've been trying to solve a problem where a Phenom processor, when coupled with 8Gb, would kernel panic under heavy load.
After testing various patches, kernel versions, and random things I believe the problem is fixed in the kernel version 2.6.27RC4 - however nothing in the changelog appears relevant, so I guess only time will tell.
Now we need to solve the problem of Atom processors panicing when attempting to boot 64-bit kernels. That is still present in the 2.6.27RC4 kernel.
(ObRandom: If there are any interested parties I can provide remote serial console access to such a system.)
Finally I've also been playing with PAM, the plugabble authentication module. Again specific use-case here. At work we want to allow people to ssh to some systems (to access serial consoles, etc), and we wish their connections to be tested against our internal single-sign-on mechanism.
That could have meant a whole new PAM module, which would do XML-RPC-fu. Instead it meant packaging libpam-external - which is a neat PAM module allowing you to specify a shellscript to validate users & passwords.
(libpam-external is very similar to mod_authnz_external which is a similar pluggable Apache2 module)
So, this week "kernel hacking", & "pam hacking". Does that make me a real developer now?
ObQuote: Time Bandits
Tags: apache2, kernels, pam
25 August 2008 21:50
Steven Brust is a big tease.
His most recent Vlad Taltos novel is full of tease for two reasons:
- He jumps back in the timeline so that we hear nothing of Lady Teldra.
- The acknowledgements of the novel mention the use of some "emacs macros" with no hint of what they are, or why he uses them.
It was a fun read though, and didn't make me as hungry as the previous volume did. (Mmmmmm
I always liked him as an author, and he rocks for publishing Dzur around the time I was telling local people "Too many people seem to write novels in which nobody really eats. Forget all that action, dialog, and exposition. Lets have a bunch of folk sit down and eat an exceptionally well described meal."
(Many things that people do are never described in books. We all know why. Still on the same subject I love the scene in Terry Pratchetts Pyramids where Teppic puts his outfit on. "And slowly falls over". Nice)
Tags: authors:brust, authors:pratchett, books, emacs
26 August 2008 21:50
So I got bored tonight and figured I'd write a game...
I'm genuinely not sure whether I've seen this concept before, or came up with it myself. I suspect the former. I know that I sat down with the intention of coding this game and knew how it would play and what the mechanics would be.
Having said that though I cannot think of a similar game I've played - though parts are obviously derivitive.
Anyway the aim of the game:
- A (single currently) ball bounces around the screen.
- You draw lines upon the screen, using the mouse, to influence the movement of the ball.
- The level (game) is over when the ball lands in the "exit box".
Thus far the game exists only in the skelital form with the minimum required functionality. There are two modes currently: "easy" & "hard". The hard mode was primarily added to prove to myself that the "leveling" system could work in a fun way.
Feedback welcome. Especially if it can tell me where I'm going wrong with the collision detection - but even if it is to critique my hacked-up SDL coding.
(The only other SDL coding I've done was in C, and was the mousetrap game.)
Obviously the game is written in perl, and I admit nasty perl at that. To play it you'll only need:
apt-get install libsdl-perl
ObQuote: The Chronicles of Riddick
Tags: bouncy bouncy, game, mousetrap, perl, sdl
27 August 2008 21:50
I've updated my simple Simple SDL based perl game, so that:
- It has a name.
- It has an intro screen which uses that name!
- It has multiple balls.
- It gets harder, ie. more balls are added.
- The collision detection is much improved.
I still need to work on the rebound-angle but otherwise it is as complete as it will probably ever become. It would also be nice if the balls could collide with each other, and be different colours..
Regardless it was a fun diversion for a few hours, and probably tells me that I shouldn't attempt to waste more time doing gamy things, and that maths is too hard for me these days.
ObQuote: Interview with the vampire
Tags: bouncy bouncy, game, sdl
31 August 2008 21:50
When volume becomes high enough you start to observe patterns in SPAM pretty easily. I think that this is primarily because people like to see patterns, whether they are present or not.
The trick is determining whether they are real patterns or not, and then to a lesser extent whether they are useful patterns.
For example I host mail for a business domain. That means that incoming messages come primarily from existing customers, and very rarely from potential new ones.
In practise that means that email is expected to arrive from 9am til 6pm (+/-2hours) Email received at 2AM? Either it is somebody working remotely, a foreign contact, or much more likely it is SPAM.
Now clearly you cannot dump all messages received at unusual times of the day, but it is a surprisingly robust SPAM indicator for that particular domain.
All heuristics are fallable, but some are useful regardless..
I'd love to know what people can learn from their SPAM. This week I'm handling approximately 80,000 messages a day, per MX, which isn't huge (ie. 2-3 million a month).