APB - AP Blog

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• Fotos •

31. Dezember 2005, 14:26

Nachtfoto

So, hier der erste Eintrag im neuen Bereich. Eigentlich laufe ich gerne mit meiner Digicam durch die Gegend. Manchmal fehlen mir die richtigen Motive, deswegen muss die Landschaft herhalten.

Besonders gerne mache ich Nachtfotos. Das ist ein Bahnübergang bei uns. Sieht mit dem Schnee einfach gut aus...

Verfasst von AP am 2005-12-31 14:26:02, letzte Änderung am 2006-04-01 22:36:21.

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• English • Technikspielzeug •

29. Dezember 2005, 01:27

Booting from a reiserfs partition with Fedora Core 4

Don't do it.

It's that simple. I've spent three days to figure this out. Big files can't be read by GRUB from a reiserfs partition correctly. In my case GRUB could not load (and show) the splash background image, as well as some kernel and ramdisk images. It always ended with a kernel panic.

The solution: make a small /boot partition (about 100MB) and format it with ext2/ext3. All other partitions can be reiserfs, as you like it.

Written by AP on 2005-12-29 01:27:37, last change on 2006-01-16 15:28:34.

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• English • Technikspielzeug •

29. Dezember 2005, 01:01

D-Link DWL-G122 USB WLAN-Adapter (RT2570) [suppl.]

Right now I'm finished with a reinstallation and other stuff. I've upgraded to FC4.

First problem: there were changes to the current kernel 2.6.14. The method verify_area has become obsolete and has been replaced by access_ok. The CVS driver version has been patched. The release 1.1.0-b1 still needs patching. Simply replace any occurence of verify_area through !access_ok. There should be two of them.
If you don't, the driver module will still compile, but you won't be able to load it.

I've also analyzed the MTU problem I mentioned in a previous post closer. The MTU problem only appears on the internal network. External connections do not need this MTU tweaking. Now I use iptables to change the packet size for incoming and outgoing connections.

iptables -I INPUT 1 -i rausb0 -p tcp -s <internal_network> --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 551
iptables -I OUTPUT 1 -o rausb0 -p tcp -d <internal_network> --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 551

Et voilà! C'est ça.

Supplemental: see also D-Link DWL-G122 USB WLAN-Adapter (RT2570) and MTU.

Written by AP on 2005-12-29 01:01:10, last change on 2006-02-02 20:05:21.

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• English • Technikspielzeug •

21. Dezember 2005, 23:45

D-Link DWL-G122 USB WLAN-Adapter (RT2570)

D-Link USB-WLAN adapter, back side (click to enlarge)

D-Link USB-WLAN adapter, front side (click to enlarge)

New toy, new tornments. Especially, if you try to find an USB-WLAN adapter, for which there are Linux drivers. An almost hopeless matter.

After I've read many contradictory statements, I spontaneously and without any reason settled for the above model.

My first try was the NDIS-Wrapper, which theoretically allows you using the windows driver. I've installed NDIS-Wrapper Ver.1.7 together with windows driver Ver.2.03 with Fedora Core 4. The installation was easy and trouble-free - this perplexed me... The driver worked even though a little bit unstable. The adapter switched into powersaving mode after longer period of inactivity, from which it could not be woken up. One can solve this problem by sending a ping to the router every minute.

Nontheles I was not able to establish an SSH connection. Thus I searched for a native Linux driver for the rt2570 (aka rt2500usb) chipset. I found some links on the NDIS-Wrapper homepage.

1. Ralink homepage. I was able to compile and load the module. The device was found, I could scan the network. But I was not able to esblish a link to my accesspoint.
2. Serialmonkey Another OpenSource project. Judged by the sourcecode its closely related the previous one. I worked a little bit better. Once the interface was up, the AP was found quite quickly.

In both cases (ndiswrapper and SerialMonkey driver) I had a problem: simple pings worked, but "normal" TCP connections did not. The problem was the packet size! After I've reduced the MTU to 591 all connections worked properly.

Supplemental: see also D-Link DWL-G122 USB WLAN-Adapter (RT2570) and MTU.

Written by AP on 2005-12-21 23:45:07, last change on 2006-02-02 20:05:08.

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• Technikspielzeug •

16. Dezember 2005, 23:01

Autoradio Tevion CRM 2005

Wer so wie ich das Gerät beim Lebensmitteldiscounter ALDI (seit wenn zählen Autoradios zu Lebensmitteln?) gekauft hat, der wird wohl wenig begeistert sein.

Äußerlich ist das Gerät schick, der Klang ist eigentlich auch ok. Allerdings kommt es regelmäßig vor, dass das Gerät sich an den MP3-CDs verschluckt und "abstürzt". Dann läßt sich die CD nicht mehr entfernen und wenn man den Input aufs Radio geschaltet hat, so läßt es sich nicht mehr auf CD zurückstellen.
Die einzige Abhilfe, die noch bleibt, ist es den RESET Knopf zu drücken. Das sorgt auch dafür, dass man anschließend seine Radiosender neu einstellen darf. Mittlerweile bin ich schon ein fast ein Experte darin. Das Radio hat es einmal geschafft zweimal am gleichen Tag abzustürzen. Die Programmierer der Firmware gehören gelyncht - oder deren Chefs.

Leider konnte ich auch keine Firmware-Updates für das Gerät im Internet finden - nur die Fehlerbestätigung.

Verfasst von AP am 2005-12-16 23:01:30, letzte Änderung am 2005-12-21 23:45:03.