Showing posts from 2012

Reverting from BTRFS to Ext4

I had to revert from compressed BTRFS to Ext4 on my tiny netbook partition, as it wasn't playing nice. That's a pity, as Ubuntu is highly compressible and compression didn't slow it down. The system occupied less than half of the space and reported such, however when I was starting to fill up the space, it complained of insufficient space. Probably because of metadata allocation. As I didn't want to reinstall the system, I went the more costly route: * I've rebuilt the partition in an image on ext4, * copied over the data * copied the initrd image from another computer of mine with the exact same system, both were updated at the same time - otherwise it couldn't read the new kind of partition * adjusted grub settings * reinstalled grub (was extra painful when I attempted to do that inside an image..).

Ubuntu 11.04 vs. Intel 865G

Hm, it looks like this post has stuck in my drafts for some years now... Compositing produces a considerable amount of flicker and the display is obstructed by random image parts. dmesg is also full of page flip errors. Solution: cat >~/.drirc <<EOF <driconf> <device screen="0" driver="dri2"> <application name="Default"> <option name="vblank_mode" value="0" /> </application> </device> </driconf> EOF service gdm restart via and Also needed to append the following to the kernel command line, or else I got a lot of squashfs block read errors: acpi=off noapic ide=nodma all_generic_ide pci=nommconf

Watching 3D TV for free using mplayer

Antenna Hungaria is testing 3D broadcast over the air for the time of the Summer Olympics and the UEFA European Football Championship . In idle time, they are scheduling lovely programs of documentary, nature and the like. Anyway, I wanted to see how easy it is to view such side-by-side content in 2D while preserving maximal quality. As anticipated, mplayer works like a charm, see the uploaded script:

PCI DVB tuner fix for timeout waiting for DSP ready

I had a similar problem as described below on Ubuntu 12.04 and found that inserting saa7134-dvb into /etc/modules.conf did the trick for me too. It's interesting though that it has been working fine before. I did recall seeing this issue once or twice, but this time it did not seem to have been resolved by multiple cold booting by itself. [ 43.162971] tda1004x: timeout waiting for DSP ready [ 43.202914] tda1004x: found firmware revision 0 -- invalid [ 43.202918] tda1004x: waiting for firmware upload... [ 48.675012] tda1004x: Error during firmware upload

Making your 3G cellular mobile Internet 10x faster for free

I've made a small script for greatly improving response time of 3G cellular data connections while only consuming a minimal amount of transfer quota. It is most noticable when browsing, having interactive ssh sessions and maybe for some remote desktop use cases. The result is basically reducing the 500ms-1500ms initial latency and random ping times to normal rates of below 80ms. Of course this assumes that you have no other problems like reflections, interference, signal strength or congestion. I've experimented with raw UDP, TCP and ICMP packets in different configurations, but sticked with this simple and efficient solution in the end. An even more advanced future implementation could involve STUN and an external server to steadily stream optimally sized and timed UDP packets to the client without ACK requirement. Also, a further enhanced version could closely monitor local transfer conditions and determine if any addition transfer should actually be done. Description fro

ZTE MF195 3G hack on Ubuntu 11.10

If you connect this modem to a machine running Ubuntu, it mounts and opens the virtual driver disk. If you unmount the partition, usb_modeswitch automatically kicks in and switches the device from CD-ROM emulation to modem mode. Unfortunately, Network Manager would not connect regardless of configuration. However, after some trial and error, wvdial was able to establish connection and start transferring data. After reducing the unknowns, I've devised a small script which waits until the drive gets automatically mounted, unmounts the device, waits for settling and then establishes a connection with wvdial. This script was hooked up to a specific device addition udev rule to make it run automagically. As the devised udev rule did not narrow down the event good enough, actually two such invocations are done for each insertion, so a bit of an ugly hacking was involved to implement mutual exclusion.

Participatory cloud computing - help cure cancer?

How come so few donate their free resources to volunteer computing projects ? Depending on the exact computer configuration, the difference in system power consumption between using and near-idling the CPU (~35W-80W) or GPU (~30W-100W) can be reasonably small . The difference is usually smaller than the difference between a power efficient (25-60W) and a basic system (100-200W). Hence in my view, it usually worths it to put your free resources to use in some way if your daily work does not strain your machine continuously at 100%. There's an a project of special interest that has similar aim to what I have invented earlier: It is special in that any participant can freely use the communal grid for their own purposes . Prioritization is fair - it is based on previous record of contribution. This type of project is also useful for the selfish kind, as if you think it over, you can eventually get back the contributed CPU time and energy, but at a much faster pace. It would stil

Fractals of mine

Although, I have uploaded these previously , here's a version which you can copy & paste into the online interpreter : to flake :s :n ifelse :n=0 [fd :s] [flake :s/3 :n-1 rt 60 flake :s/3 :n-1 lt 120 flake :s/3 :n-1 rt 60 flake :s/3 :n-1] end to koch :s :n pu fd :s*57/100 pd rt 210 repeat 3 [flake :s :n lt 120] lt 210 pu bk :s*57/100 end to put1 :s :n :k setpencolor :n+2 koch :s :n pu fd :s*12/10 pd rt 360/:k if :n>0 [put1 :s :n-1:k] end to put :s :n pu lt 135 fd :s rt 135 put1 :s :n-1 :n end cs put 100 5

Software Quality at Top Speed

Fine literature has been available for decades now, but some still don't seem to get it right. Software Quality at Top Speed by chief software engineer Steve McConnell (Software Development, August 1996) highlights reasons for project overruns and the importance of taking time to design and do reviews Quality Cost Analysis: Benefits and Risks by Cem Kaner (Software QA, Volume 3, #1, 1996, p. 23.) details the economic side

Read a file by inode - the hard way

I found a nice hack to undelete an open file: Undeleting an open file by inode Though, I generally use cat , as that's much easier. It's also useful to view cached content of plugins which delete their files upon download.

Cross compiling Qt to 64-bit

The following didn't work by itself: How can I build 64 bit Qt on a 32 bit system ? The solution was to simple set the write-protect flag on the exe files under qt/bin (on moc, jom, etc.).

New e-mail anti-spoofing protocol built on SPF

I've always wondered what best practices should be applied when handling DKIM mail, and started considering manual verification and domain based whitelisting. I welcome the draft that is emerging to offer a standard framework for just these questions. News entry: new anti-spoofing protocol built on SPF - DMARC

Open Source Ecology project

I've always adored open hardware and generally the concept of helping each other out. There's this project which gives you blueprints and recipes for living an environmentally responsible, though frugal life. Really makes you want to put down your keyboard and start agriculture work right away!  Open Source Ecology project at Wikipedia I'd need to review their current status, but generally, you can do cleanroom designs easily made of common household items. I'm not sure if they have the needed plans and documentation for such simple items under their umbrella, but a well structured collection of wiki links could also do the trick in these cases.

purifying your thoughts

"Always aim at complete harmony of thought and word and deed. Always aim at purifying your thoughts and everything will be well." - Mahatma Gandhi on unit testing .

ntuser.dat - P:\oxvy

I was just reading through the binary dump of a computer's registry that I've been using, and I found some very nice strings, like oxvy. I know at least one person who knows what that means. ;) edit: A hint is that you should consider what trivial encryption/obfuscation schemes are wide spread.

FreeGuide EPG with daemonized XMLTV

I'm evaluating FreeGuide , an electronic program guide supporting XMLTV . I wrote a tool to grab the TV guide for a few days in advance. I schedule it to run on startup and twice an hour. I have to run it so often as my PC at home is only switched on for a few hours each day (either manually or via automated recording scheduler ). Note that polling would be unneeded after correctly implementing a universal power scheduler . Despite such frequent invocation, it only executes the core process if no update has happened in the last two days. It also splits the downloaded guide by days to lower processing in the update helper below and to make a possible future selective update easier. I made an update helper for FreeGuide which keeps track of the data which was imported to the viewer previously and initiated importing of only the new parts. One of my next projects will be to install and tweak teletext based XMLTV provider for Hungarian norms .

naked domain seems to be working somehow

I'm not sure how they managed to finally set up naked domain redirection, or if it's a present from Google, but I sure am delighted! :) My cards contained only the naked domain you know...