Archive for 2012

April 1st in Technology

More interesting things will probably come up during the day, but so far I liked Google’s idea (also see a link from google.com).

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Definetly the weirdest LDAP management tool

Its called ldapvi, and its just about what you’d expect with that name :-). The author would like you to think about it as vipw for your LDAP based authentication, and in addition to a few command line option it really isn’t much more then that (UI-wise):

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Nvidia Optimus on Ubuntu 12.04

Nvidia Optimus is a neat solution to the problem of power consumption vs. 3D performance in notebook computers – the computer comes with two graphics chips, an “integrated graphics package” – the Intel GMA embedded graphics and a “discrete graphics package” – the Nvidia chip. The setup works by running your normal windowing UI on the integrated graphics, only powering on the discrete graphics when you want to play a 3D game or something like that.

Recently I had the fortune to work on a Lenovo T420 laptop1 that has this setup, and it works very well on MS-Windows with the Nvidia Optimus driver – you get battry life around 10 hours with the 9 cell battery.

Unfortunately I spend most of my day in Linux and because Nvidia does not support Optimus on Linux, you have the poor choice of either running everything on the Nvidia chip – decreasing battery life to around 4 hours if you’re careful, or disabling the Nvidia chip completely.

The solution comes from the Bumblebee project – a software suite to handle the switching between the Nvidia discrete graphics and the embedded Intel chip.

The setup is pretty simple to understand (though I suspect under the hood there are many problems to be solved): A service runs and waits for users to ask for 3D accelerated graphics. When a user starts a program using the special command optirun, the service loads the Nvidia driver, starts an X server using the discrete graphics (with the display disconnected from the actual screen) and runs the specified program on that “background” X server. Then it copies the visuals from the program that is rendered using the discrete graphics to a window on the main X server. When the program terminates, the service closes the secondary X server, removes the driver and powers down the graphics card – putting us back into the ~10 hours battery life.

The Bumblebee software had some problems in the past, but the current version – 3.0 – looks very good. There are a few seconds of delay when you launch the application (setting up the driver and X takes some time), but performance is about what you’d expect when running directly on the hardware. All this without any configuration – that is if you are running on the stable Ubuntu version.

As I can’t leave well enough alone, and whenever someone says “alpha”, I say – “I wants”, I’m running the current Ubuntu 12.04 alpha (which is not so bad – due to be released in a couple of months, it works very well). And of course Bumblebee doesn’t work properly here.

So this is what I had to do to get it running:

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  1. with an amazing 1600×900 screen, what they call “HD+”. Truly a work of art []

LDAP authentication on Fedora 16 (and why it sucks)

In my company we (still) use an Active Directory domain controller to manage central authentication1, which is not set up very well – no SSL and the Kreberos setup is not done properly. This makes gives much trouble to modern Linuxes (e.g. not Ubuntu. yes – I’m looking at you Shuttleworth.)  such as Fedora, as Fedora have done away with NSS/PAM based LDAP authentication and instead relies on SSS – which I have yet managed to get working or even find a tutorial on how to set it up properly.

So if you still want to authentication your Fedora installation against the company’s Active Directory – and can’t/won’t rely on Winbind’s notably flaky behaviour, you can always install NSS/PAM ldap authentication manually. Unfortunately its not as easy as it sounds, and as I learned the hard way – one must pay careful attention to SELinux. So here’s the recipe:

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  1. there are a lot of MS-Windows workstation, so it kinds of makes sense – but we are planning to phase it out in favour of OpenLDAP, so don’t worry about it []

Scanning Hand Written Texts Into High Quality Digital Files

The purpose of this exercise is to convert a hand written note – such as your signature – to high quality digital files that can be used to embed “hand write” into documents – such as when someone asks you to fax them a “signed” copy of the PDF they emailed you. You’d be surprised how often that happens around here.

Required Ingridients:

  • A computer with The GIMP installed
  • Your handy smart phone with a 5MP or better camera
  • A good pen and paper.

So anyway, here’s the process from top to bottom, with pictures:

  1. Sit down at a proper table, and using a good black heavy-line pen1 on a white clean high-density paper, write what you need to write – slowly and deliberately but without pauses. Try not to smear the ink so you get clean continuous lines, otherwise the quality suffers a lot.
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  1. in this shot I used a 0.7 permanent marker – which is just overdoing it – probably any 0.7 pen will work []

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