Get the minimal root fs

1. Check out Docker images for CentOS: https://hub.docker.com/_/centos/
2. Follow the Dockerfile link for the version you're interested in, say 6.6: https://github.com/CentOS/sig-cloud-instance-images/blob/8911843d9a6cc71aadd81e491f94618aded94f30/docker/Dockerfile
3. Go one level up in GitHub and locate the centos-*.tar.xz file, it's the archive with the mininal rootfs for CentOS: https://github.com/CentOS/sig-cloud-instance-images/blob/8911843d9a6cc71aadd81e491f94618aded94f30/docker/centos-6.6-20150304_1234-docker.tar.xz
4. Click the download link

Prepare a directory, unpack the root fs

sudo mkdir -p /mnt/centos-chroot/ # You may need to uncompress the XZ file, but my tar could deal with it, so try yourself: sudo tar -xf /path/to/centos-6.6-20150304_1234-docker.tar.xz # Mount some pseudo filesystems: cd /mnt/centos-chroot/ sudo mount --bind /sys sys sudo mount --bind /dev dev sudo mount -t proc proc proc

Enter your precious chroot:

sudo chroot /mnt/centos-chroot/ /bin/bash . /etc/environment

Done!

by Gabrys

Be able to manage and run "tasks" on a Linux server. More specifically:

• There should be a WEB interface where:
  • I could define commands or tasks that the server is capable of doing
  • I could schedule tasks to run at specific times (like cron)
• The tasks/commands should be (optionally) parametrized
• The tasks/commands should be (optionally) stored in GitHub and/or a database
• The task runs should not overlap with each other (i.e. when the previous run is still in progress don't start the new one) — configurable
• The task configuration should include:
  • the command to run
  • task timeout — the task should be killed after the specified time
  • environment variables to set for the task
  • max CPU/memory/disk to use (optional)
  • number of times to retry on failure
  • what to do on success and failure — e-mail, webhook and trigger another task
  • directory to run the command in: I can specify one, or a temporary one is created for each run and cleared after the run
  • user to run the command as: I can specify one, or a temporary user is created for each run and cleared after the run
• The task run view should include
  • colored command output
  • command exit code: OK/FAIL
  • resources used by the task (optional)
  • time the task took, time the task started and ended
  • environment variables
  • link to next/previous run and a button to re-run
• The code should be free and open and extremely easy to install
• There should be an error log in the UI to track all the jobs failures
• Misconfigured tasks should not take the machine down — there should be some level of monitoring — don't start new jobs when load is high or disk is almost full, etc
• One should be able to have a nice dashboard with selected tasks for easy launching

What I describe here is to some extent already covered by some of the following:

• Jenkins https://jenkins.io/
• Travis-CI https://travis-ci.com/
• Rundeck http://rundeck.org/
• Minicron https://github.com/jamesrwhite/minicron/

Here's what's wrong with them:

• Jenkins' UI is to complicated for simple tasks, also it feel very heavy
• in Travis-CI you specify the tasks in your code, not in Travis, also it's not software you run locally
• My experience with Rundeck is it doesn't work out of the box, I could debug it, but I didn't want to, also UI is a bit too complex
• Minicron is way too simple and (currently) only allows you to run jobs through ssh (not locally)

To reiterate I'd like:

• A web UI for cron, that's also
• a bit like Jenkins in a way you can see the output of each of the command runs
• and have ability to sandbox the processes it runs
• looks nice and is easy to install and doesn't require maintenance

by Gabrys

$ synclient CoastingSpeed=0

by Gabrys

The webcam reader

I decided, it's time to record the temperature, so I brought the laptop, adjusted the screen angle, set the brightness to max and took a shot from the webcam to see if the thermometer is in the view of the camera:

mplayer tv:// -vo png -frames 3

This takes 3 frames from the webcam and saves them as PNG files: 00000001.png, 00000002.png, and 00000003.png. If you wonder why I need 3 frames, the first one is always under- or overexposed and out of focus, the second is usually OK and the third is almost always good (as for a webcam), so long story short, I'm giving some time to the camera to auto-adjust its settings.

Here's a script that does just a bit more than that:

#!/bin/bash set -e export DISPLAY=:0 curdate=`date +%x-%X | sed 's/[\.:]//g'` outpng=/home/quake/git/thermonitor/out/"$curdate".png tmppng=/home/quake/git/thermonitor/tmp/00000005.png mkdir -p /home/quake/git/thermonitor/out/ /home/quake/git/thermonitor/tmp cd /home/quake/git/thermonitor/tmp # White background ristretto ../white.png & # Wake screen xte "mousemove 100 100" sleep 0.2 xte "mousemove 99 99" # Dump screen mplayer tv:// -vo png -frames 5 -noconsolecontrols cp "$tmppng" "$outpng" echo "$outpng" kill $!

It's very hacky, but here are the big parts:

• set -e makes the script stop if any of the commands in it fail
• export DISPLAY=:0 selects the default X display, so I can run the command from an SSH shell
• Then we have some hard-coded paths to tmp and out directories
• ristretto ./white.png & starts a image-viewer and shows a white.png file which is a big all-white file. This makes the screen display enough white, so the LCD thermometer is properly lit
• I use xte to move the mouse around: this blocks the automatic screen dimming, so the screen continues to be 100% bright
• Then we have the mplayer command from before, just changed to 5 frames (just to be sure) and -noconsolecontrols. mplayer kind of hangs when you start it without a proper terminal on stdin, unless you pass this option
• Then I copy the 5th frame to the output file, which has the current date and the time in its path
• Finally I close the ristretto process I opened before

I run this command in a while loop like that:

while sleep 28 ; do ./dup.sh ; done

./dup.sh takes around 2 seconds, so I have about 2 photos a minute.

I put that to a screen session.

Now in the out directory I serve the files using Python HTTP server:

python -m SimpleHTTPServer

This starts an HTTP server on port 8000 and serves all the files and creates an index of them when requesting /.

The processing

How easier to copy the HTTP-exposed files than using a plain-old wget command?

wget -r http://dell:8000/

This creates directory dell:8000 and downloads all the PNG files to it.

Once you have that directory you may later want to update it with only the newer files:

rm dell\:8000/index.html wget -nc -r http://dell:8000/

The -nc switch makes wget ignore files that are already there. We explicitly remove the index.html so it downloads a new list (that includes newer files).

I wanted to make a program that gets a photo of the 7-segment display and reads it producing a number that along with the date could be used to graph the temperature over time.

First, let's use ImageMagick to:

• crop the picture to only the interesting part: the OUT reading
• shear the picture to make the LCD segments vertical and horizontal, not skewed
• bump contrast/gamma to remove the noise
• auto-adjust the visual properties of the picture so it's more consistent across different times (like night vs day)
• make it black and white — turned out it works best if I only use the Green channel, R and B turned out more noisy than G.
• resize to as small size as needed — for easier and faster processing

Here's the actual command:

convert $file_in -gamma 1.5 -auto-level -brightness-contrast 35x80 -shear -14x0 -crop 260x70+320+227 -channel Green -separate -resize 40x20 $file_out

Input image:

Output image:

Zoomed in:

You can see the bottom segment is not really visible, but that's OK, all the digits can be properly read without that segment being visible, so we'll only consider the 6 segments that we can easily read.

Now comes the meat, the Python program reading the file and returning the temperature:

#!/usr/bin/env python #encoding: utf-8 from PIL import Image # Points that hold each segment: # d1 is the first digit d1_sA = [(12,1), (13,1), (14,1), (15,1)] d1_sB = [(18,2), (18,3), (18,4), (18,5)] d1_sC = [(18,8), (18,9)] d1_sE = [(11,8), (12,9), (11,9), (12,8)] # Don't need this, as we only ever have 1 and 2 in the first place d1_sF = [] d1_sG = [(13,7), (14,7), (15,7), (16,7)] # d2 is the second digit d2_sA = [(24,1), (25,1), (26,1), (27,1)] d2_sB = [(29,2), (29,3), (29,4), (29,5)] d2_sC = [(29,8), (29,9)] d2_sE = [(22,8), (22,9)] d2_sF = [(22,2), (22,3), (22,4), (22,5)] d2_sG = [(24,6), (25,6), (26,6), (24,7), (25,7), (26,7)] # d3 is the small digit (first after the decimal point) d3_sA = [(35,4), (36,4), (37,4)] d3_sB = [(38,5), (38,6), (38,7)] d3_sC = [(38,9)] d3_sE = [(34,9)] d3_sF = [(34,5), (34,6), (34,7)] d3_sG = [(35,8), (36,8)] # Now the tricky part, for each segment I define a threshold below which I consider it "lit" # 0 means completely black, 255 is white. # Because of uneven lighting, for each segment (and digit, but we ignore that) the value is different. tA = 200 tB = 170 tC = 120 tE = 115 tF = 140 tG = 170 # A threshold for the "-" sign tSIGN = 200 # All of those were obviously updated on the go to match the files # A nice debugging function that prints which segments the code considers lit # Also if you wondered what A, B, C, E, F, G meant, here's the schematic: def print_digit(segs): # Only print this if there's a second argument to the script passed if len(sys.argv) == 2: return print ''' {A}{A} {A}{A} {F} {B} {F} {B} {F} {B} {G}{G} {G}{G} {E} {C} {E} {C} {E} {C} '''.format( A='###' if 'A' in segs else ' ', B='###' if 'B' in segs else ' ', C='###' if 'C' in segs else ' ', E='###' if 'E' in segs else ' ', F='###' if 'F' in segs else ' ', G='###' if 'G' in segs else ' ', ) # This doesn't do anything spectacular, just passes the coordinates for each of the segments and the average value of the first 9 pixels of the image: (0,0) - (3,3) def read_digit(im, pointsA, pointsB, pointsC, pointsE, pointsF, pointsG, avg9px): segs = '' segs += 'A' if read_segment(im, pointsA, tA-avg9px) else '' segs += 'B' if read_segment(im, pointsB, tB-avg9px) else '' segs += 'C' if read_segment(im, pointsC, tC-avg9px) else '' segs += 'E' if read_segment(im, pointsE, tE-avg9px) else '' segs += 'F' if read_segment(im, pointsF, tF-avg9px) else '' segs += 'G' if read_segment(im, pointsG, tG-avg9px) else '' print_digit(segs) # A list of all digits and their representation on the 7-segment display: if segs == 'ABCEF': return 0 if segs == 'BC': return 1 if segs == 'ABEG': return 2 if segs == 'ABCG': return 3 if segs == 'BCFG': return 4 if segs == 'ACFG': return 5 if segs == 'ACEFG': return 6 if segs == 'ABC': return 7 if segs == 'ABCEFG': return 8 if segs == 'ABCFG': return 9 # A special case for the first digit, it doesn't display "0", just doesn't display any segments if segs == '': return 0 # The function that takes the PIL image object, gets a list of (x,y) coordinates # and checks if the average value of them is smaller than the threshold passed: segment "on" # For 0 points passed it returns False: segment "off" def read_segment(im, points, threshold=128): val = 0 for point in points: val += im.getpixel(point) return val < threshold * len(points) # Nothing interesting in here, just for printing the date from the file name def get_date(file_name): time_str = file_name.split('-')[-1].replace('.png', '') d1, d2, m1, m2, y1, y2, y3, y4 = file_name.split('/')[-1].split('-')[0] return '{}{}/{}{}/{}{}{}{} '.format(m1, m2, d1, d2, y1, y2, y3, y4) + '{}{}:{}{}:{}{}'.format(*list(time_str)) # A bunch of imports in the middle of the file # Don't do that at home ;-) import sys import subprocess # This will be for example: pngs/dell\:8000/24092016-101055.png file_in = sys.argv[1] # And this: processed-pngs/dell\:8000/24092016-101055.png file_out = 'processed-' + file_in # Calling the ImageMagick as discussed in the article subprocess.check_call(['convert', file_in, '-gamma', '1.5', '-auto-level', '-brightness-contrast', '35x80', '-shear', '-14x0', '-crop', '260x70+320+227', '-channel', 'Green', '-separate', '-resize', '40x20', file_out]) # Reading what it created im=Image.open(file_out) # Now a thing I added at some point later. # Because of different lighting throughout the day and because the ImageMagick command # above was not good compensating for it (in spite of auto-level and high contrast) # some of the images were darker than the others. In most images (the ideal scenario for the code) # the first 9 pixels of the image (0,0) to (3,3) were just white (or very close), but in those darker # images the whole image was darker and I used the first 9 pixels to detect how much darker first9px = im.getpixel((0,0)) + im.getpixel((0,1)) + im.getpixel((0,2)) \ + im.getpixel((1,0)) + im.getpixel((1,1)) + im.getpixel((1,2)) \ + im.getpixel((2,0)) + im.getpixel((2,1)) + im.getpixel((2,2)) # This is the compensation, for most of the images it's 0 or very few, but for darker images, it's more avg9px = 255-first9px/9 num = '{}{}{}.{}'.format( '-' if read_segment(im, [(2,6), (3,6), (4,6)], tSIGN-avg9px) else '+', read_digit(im, d1_sA, d1_sB, d1_sC, d1_sE, d1_sF, d1_sG, avg9px), read_digit(im, d2_sA, d2_sB, d2_sC, d2_sE, d2_sF, d2_sG, avg9px), read_digit(im, d3_sA, d3_sB, d3_sC, d3_sE, d3_sF, d3_sG, avg9px), ) if 'None' not in num: print get_date(file_in) + '\t' + num # If there's a second argument to the script passed, show the original image for comparison if len(sys.argv) > 2: Image.open(file_in).show()

Even though this script is so simple, after tweaking the thresholds, most of the files were recognized correctly, those that weren't had one or more non-recognized digits, so they were easy to filter out. For over 1-day worth of images, only 2 or 3 minutes had a missing reading.

I loaded the data to LibreOffice and generated this pretty graph:

Timelapse video

Another approach visualizing the data was to create a video.

The plan:

• Annotate the images with the recorded time
• Compose the video from single frames, putting 60 frames per a second of the resulting video

60 frames a second with roughly 2 frames captured a minutes means a day of recording is compressed to:

2 frames a minute * 60 minutes an hour * 24 hours a day = 2880 frames 2880 frames / 60 frames a second = 48 seconds

This makes is "viewable". 60 FPS (versus 30 FPS at higher speed) means you can pause at any time and read the crisp time and temperature.

Here's the annotate part:

#!/usr/bin/env python import sys import subprocess path_in = sys.argv[1] path_out = sys.argv[2] date, time = path_in.replace('.png', '').split('/')[-1].split('-') D1, D2, M1, M2, Y1, Y2, Y3, Y4 = date h1, h2, m1, m2, s1, s2 = time label = '{}{}/{}{}/{}{}{}{} {}{}:{}{}:{}{}\\n'.format(M1, M2, D1, D2, Y1, Y2, Y3, Y4, h1, h2, m1, m2, s1, s2) subprocess.check_call([ 'convert', path_in, '-gravity', 'south', '-pointsize', '45', '-font', 'FreeMono', '-annotate', '0', label, '-fill', 'black', path_out ])

Here's the result:

Running this in a loop, 16 images at a time:

#!/bin/bash i=0 for file_in in dell*/*.png; do file_out="`printf "labeled/%06d.png" $i`" echo ./add-labels.py "$file_in" "$file_out" i=$((i+1)) done | parallel -j 16

In addition to annotatig the image it also names them as 000001.png, 000002.png etc, which makes it easy for avconv to convert them to a video:

avconv -fflags +genpts -r 60 -i labeled/%06d.png -r 60 temperature.mkv

And here's the video:

by Gabrys

Ogólnie moja opinia na temat samochodów i ich ekranów multimedialnych, jest taka, że dla wszystkich byłoby dużo lepiej, gdyby producenci samochodów przestali się tym w ogóle zajmować, tylko dali jakąś dobrą integrację z tabletem, który można byłoby sobie wsadzić w odpowiedni slot w samochodzie.

Ale do rzeczy. Dlaczego system w aucie, który kupiliśmy jest według mnie taki słaby?

Po pierwsze sposób w jaki startuje. Nawigacja i reszta bajerów (radio, odtwarzacz MP3 itd) uruchamia się dopiero po "przekręceniu kluczyka". Uruchomienie systemu trwa około minutę, więc nici z szybkiego ustawienia nawigacji czy wyboru stacji przed ruszeniem w podróż.

System mógłby już zacząć się uruchamiać gdy otwieramy drzwi a nawet gdy kluczyk zbliża się do auta (mamy czujnik bliskości), wtedy długi czas uruchamiania systemu (o ile nie można go sensownie skrócić) nie byłby taki straszny, bo proces miałby miejsce zanim wsiądziemy do auta.

Po drugie brak możliwości sterowania nawigacją w czasie jazdy. Gdy przekraczamy około 5 mil na godzinę nawigacja przechodzi w tryb ograniczonego sterowania: niemożliwe jest wpisywanie adresu czy nazwy pożądanego punktu, a jeśli nazwę już wpisaliśmy w czasie, gdy auto się toczyło: niemożliwe jest zatwierdzenie wpisanej nazwy.

Są dostępne tylko niektóre opcje, wybrane chyba zupełnie losowo, bo o logice ciężko w tej sytuacji rozmawiać. Auto nie jest zainteresowane kto obsługuje nawigację. Niezależnie od tego, czy następny punkt podróży chce wpisać kierowca czy pasażer "z powodów bezpieczeństwa" jest to niemożliwe.

W sytuacji gdy jedziemy autostradą i w wyniku zmiany planów (np. ktoś się źle poczuł i należy podjechać po drodze do apteki) należy zatrzymać auto (albo zwolnić do około 5 mph) i dopiero wtedy możliwe jest ustawienie następnego punktu podróży.

Jeśli w Mazdzie nazywa się to bezpieczeństwem (zatrzymywanie auta na autostradzie), to jest po prostu głupia (tak jak i ich nawigacja).

Po konsultacji na forum Mazdy6 w Polsce dowiedziałem się, że zabezpieczenie, o którym piszę wcale nie występuje w Polskich samochodach. Bardzo mnie to zdziwiło, bo jeżeli to kwestia bezpieczeństwa, to chyba powinno to działać tak samo we wszystkich krajach? Dla dociekliwych, to też nie kwestia regulacji prawnych w stanach, bo inne marki samochodów nie utrudniają w ten sposób życia swoim kierowcom.

Jak zwykle w takich sytuacjach zwróciłem się do Mazdy z pytaniem jak to naprawić.

Niestety nie mam zapisanego mojego pytania, ale dotyczyło ono dlaczego niemożliwe jest w aucie sterowanie nawigacją (nawet przez pasażera) w czasie jazdy. Oto odpowiedź:

Dear Piotr Gabryjeluk,

Good Morning

Apologies that you are unhappy with our navigation system , to answer your question about operating the navigation while the vehicle is in motion , for safety precautions it could be a distraction to operate while in the vehicle is in motion. For the other issues with the navigation if it is not working as normal I suggest taking the vehicle into a local Mazda dealer to inspect your concern.

Thank you for contacting Mazda Customer Experience Center.

If you have any questions in the future, you can reach me directly using the number and extension below.

Sincerely,

William

Representative, Customer Experience

Nie można takiej odpowiedzi pozostawić bez odzewu, więc zadałem kolejne pytanie w nawiązaniu do tej odpowiedzi:

Dear William,

Could you please tell me how exactly operating the navigation system by a passenger is a distraction?

Thank you very much,
Piotr Gabryjeluk

Po ośmiu dniach nie dostałem żadnej odpowiedzi, więc zapytałem:

Hi there,

Am I going to get the response from William?

My issue is definitely NOT SOLVED!

Thanks,
Piotr Gabryjeluk

Odpowiedź:

Dear Piotr Gabryjeluk,

Good Morning Apologies but it looks like I did supply the answer for you in regards why your not able to use the navigation while vehicle is in motion.

Thank you for contacting Mazda Customer Experience Center.

If you have any questions in the future, you can reach me directly using the number and extension below.

Sincerely,
William
Representative, Customer Experience

Moja odpowiedź:

Dear William,

You claimed that my navigation system cannot be operated by the passenger, because it is a security threat. I asked you why is that a security issue. You did not answer to that. Please answer that question.

Thank you,
Piotr Gabryjeluk

Brak odpowiedzi. Nikt się nie przejmuje. Po przeszukaniu Internetu mam wrażenie, że nie tylko ja mam ten problem i wszyscy są jednakowo ignorowani przez Mazdę.

Jak to naprawić?

Skoro Mazda ma w dupie wygodę klientów, może jest jakiś sposób na naprawę problemu? Wygląda na to, że jest to możliwe. Na stronie forum Mazdy6: http://forum.mazda6club.com/car-electronics/351338-infotainment-hacks.html znalazłem informację o tym, że problem może być rozwiązany przez zalogowanie się przez ssh do samochodu i wyłączenie flagi.

Tylko jak się zalogować? Okazuje się, że wystarczy podpiąć kartę Ethernetową do złącza USB w aucie, a auto pobierze adres IP przez DHCP, następne pod tym adresem na standardowym porcie SSH należy się zalogować na roota (hasło jci), przemontować system plików w tryb read-write mount -o rw,remount / a następnie wyedytować skrypt /jci/scripts/set_lvds_speed_restriction_config.sh wykomentowując linię zawierającą enable_speed_restriction.

Co z tego wynika?

Jeżeli to prawda (jeszcze tego nie sprawdzałem), to znaczy, że Mazda mając techniczną możliwość zdjęcia "zabezpieczenia" (które zresztą jest włączone tylko w niektórych krajach) odmawia tego klientom powołując się na kompletnie bezsensowne argumenty (że jest to podobno kwestia bezpieczeństwa). Dodatkowo obsługa klienta Mazdy nie odpowiada na pytania i ignoruje klientów.

Jednocześnie, zgodnie z opiniami Mazdofili, wychodzi na to, że Mazda postawiła na sprawdzone rozwiązanie (wygląda na to, że pod "maską" systemu infotainmentu mamy dość standardowego Linuxa) co powinno się przełożyć na niezawodność systemu.

Kwestię umożliwienia logowania na konto roota i trzyliterowe hasło zostawiam bez komentarza. Auto nie jest standardowo podłączone z Internetem i wymagany jest fizyczny dostęp do samochodu, żeby się dostać do systemu. Zakładam, że takie "standardowe" hasło i logowanie bezpośrednio na konto roota ułatwia pracę serwisantom, więc nie widzę w tym dużego zagrożenia.

Linki

• http://forum.mazda6club.com/car-electronics/351338-infotainment-hacks.html
• https://github.com/mazdahacks/tweaks
• http://mazda3revolution.com/forums/2014-2016-mazda-3-skyactiv-audio-electronics/104730-index-infotainment-project.html
• http://openmzdc.wikia.com/
• http://www.lukasz-skalski.com/portfolio/mazda-media-player/ (klonowanie obrazu z Androida na wyświetlacz Mazdy)

by Gabrys

The problem is that even though the TV has an USB port and Roku has a "Roku Media Player" channel that allows you plan video and audio files from the USB disk, not all formats are accepted.

Interestingly Roku has support for subtitles, but the support is quite limited. I found out that one of the options that work nicely is to have the subtitles embedded into the movie itself, given the movie uses Matroska container (.mkv files).

On a side note, if the files are not encoded "properly" (Roku only supports a selection of video and audio codecs), you'll need to re-encode the video using ffmpeg or avconv, but how to do it is much simpler to Google than how to deal with the subtitles. In this post I'll only show you how to deal with the subtitles.

So let's see what we have:

quake@quake-laptop:~/movies$ ls movie.mp4 movie.txt

There's a MP4 file and subtitles in a separate file.

quake@quake-laptop:~/movies$ avconv -i movie.mp4 -f microdvd -sub_charenc cp1250 -i movie.txt -c:v copy -c:a copy movie-with-subs.mkv

Let's look at this command part by part:

• avconv — the tool we're using
• -i movie.mp4 — the movie to convert
• -f microdvd — format for the subtitles (this part is actually optional)
• -sub_charenc cp1250 — the encoding of the subtitles (optional if UTF-8)
• -i movie.txt — the subtitles
• -c:v copy -c:a copy — copy the audio and video stream (rather than re-encode)
• movie-with-subs.mkv — the output file

Which is very nice is this command will not do any re-coding, it will only repackage the movie from MPEG to Matroska container and convert the subtitles. This means there's no quality lost and it only takes a few seconds.

As noted above if the file is not playable on Roku (or there's audio missing) you may actually need to transcode the file (omitting or modifying the -c:v copy -c:a copy line).

by Gabrys

My approach to this issue was to use PulseAudio software mixer capabilities, so the hardware mixer is never adjusted (other than for the initial setup).

Step 1. Getting PulseAudio to use the software mixer

I found no good documentation on this other than PulseAudio uses paths to convert the desired volume to the hardware mixer settings and if it lacks the ability to do so it would turn the volume up/down using software. Reading between the lines I realized if I remove the paths I will get what I want. Just do this and restart pulseaudio and you'll have PulseAudio doing all the mixing in software:

sudo mv /usr/share/pulseaudio/alsa-mixer/paths /usr/share/pulseaudio/alsa-mixer/paths.bak

Verifying it works

Open two terminal windows. In each of them open alsamixer. Both should display very simple controls and say Card: PulseAudio. Use F6 to switch to the real card in one of the windows. Usually the cards have plethora of controls, so should yours.

Now change the output volume in the alsamixer still saying "Card: PulseAudio". If the volume reported by the other alsamixer does not change, it works as expected!

If you now rename the paths directory back and restart the pulseaudio process, updating the PulseAudio volume should update the real device volume as well.

Step 2. Integrating this with XFCE (or other DE)

The way xfce4 handles the volume is two-fold:

• There's a xfce4-volumed daemon. It only controls the key bindings. It binds volume up, volume down and mute keys to control the real device controls
• There's a panel applet called "Audio Mixer" that shows the current volume level and lets you change the volume as well.

Both component are optional and both seem to not work with PulseAudio (even through PulseAudio ALSA emulation which tricks alsamixer for instance).

We're going to overcome this problem by replacing these components with two other programs.

pa-applet

pa-applet will replace the "Audio Mixer" applet. The difference is the pa-applet docks to the systray, so is not XFCE-specific. The downside is we don't have control over the specific position of the icon, all we know is it will appear in the systray (so don't forget to have the systray applet added to the panel).

In order to install this software you need to clone the source, and run ./autogen.sh, ./configure, make, sudo make install. You will get information about deps missing, for instance:

configure: error: Package requirements (glib-2.0) were not met: No package 'glib-2.0' found

You need to find the proper *-dev package for each unmet dependency (for this one it will be libglib2.0-dev).

I came across one additional problem. The software seems not updated after some GTK+ 3 updates and it uses a deprecated function. Because the code is configured in a way that every warning stops the compilation, it wouldn't let you compile the code unless you open the src/Makefile file and then find and remove the -Werror flag from it.

xfce4-volumed-pulse

This part will take care of binding the media keys to the pulse audio controls (rather than to the sound card controls).

You need to download the tar package, untar it, ./configure, make, sudo make install. It also requires quite a few libs to be installed, but I didn't found any issues when compiling.

Hooking this up together

Since I didn't need the original xfce4-volume anymore I decided to remove it:

apt-get remove xfce4-volumed

But because XFCE will try to launch this anyway on each start, I decided to take advantage of it and replace it with a script:

#!/bin/bash /usr/local/bin/xfce4-volumed-pulse /usr/local/bin/pa-applet

Add the executable bit, restart the laptop and all should be working correctly at this moment.

Setting the hw mixer controls

Since PulseAudio won't update the hw controls after you follow up this little howto, it's quite important to set all the important channels to 100% (or other number up to your taste). The way to update the hw controls was described before.

Open the terminal, type alsamixer and hit F6. This will give the list of ALSA devices besides the PulseAudio emulation, your real sound cards should display as well. Choose the right one and you should be given access to tweak the real card controls.

Note if you removed the PulseAudio paths, the PulseAudio controls wouldn't update when you tweak the hw controls.

by Gabrys

I quickly set this up using Apache. Here's the virtual host file:

<VirtualHost *:8371> ServerName localhost ProxyPreserveHost Off SSLProxyEngine On Header edit Set-Cookie secure;.HttpOnly HttpOnly RewriteEngine On RewriteRule ^/(.*) https://remote-server.com/$1 [P,L] ProxyPassReverse / https://remote-server.com/ </VirtualHost>

You need to enable the following modules for that: proxy, proxy_http, rewrite, headers

Note, above I also mangle the Set-Cookie response headers in a way, that every http-only secure cookie (this means a cookie is transmitted to the server only over a secure transport and is not available on the client side) is converted to a http-only but non-secure.

The rule I produced (convert regexp "secure;.HttpOnly" to just "HttpOnly") may not work for you because I targeted one particular service and the construction of such cookies may be different for the one you want to proxy.

The second note is that, the service you're proxying might actually check the protocol on the client side as well, which we cannot mock on the server-level. I was lucky my service didn't have such checks.

by Gabrys

After spending some time figuring out why this doesn't work out of the box, I learned most of the tutorials are not right about one thing. They claim to share the network in the same (sub)network you don't need any special configuration on the client. That's wrong. You need to install cups-browsed package on the client:

sudo apt-get install cups-browsed

Then you just wait 30 seconds and you're remote printers should appear in http://localhost:631/printers

If you want to print from a different network (or your stupid router doesn't bridge Wifi and Ethernet networks) you may need to add a line like that:

BrowsePoll server-name

to the /etc/cups/cups-browsed.conf file.

An update: actually BrowsePoll server-name doesn't seem to work. I needed to replace the server name with the server IP address.

by Gabrys

Teraz Flash na Linuksa dostępny jest tylko w wersji 11. Jak chcesz wersję 12, to musisz mieć Chrome'a. Można jakimś hakiem wyciągnąć z Chrome'a samą wtyczkę i wrzucić do Chromium, ale to już trochę bez sensu.

Natomiast o Moonlighcie to już chyba wszyscy zapomnieli. Przekierowanie ze strony Microsoftu (gdzie kierują strony "brak wtyczki) prowadzi do 404-ki, w apcie susza, w sumie nie wiadomo co robić.

Ale dzisiaj odkryłem rozwiązanie obu problemów. Nazywa się ono pipelight. Jest to sprytna biblioteka instalująca Windowsowe wtyczki do przeglądarek jako wtyczki do przeglądarek na Linuksie, np. Firefoksa. Korzysta to z wine'a i sprawdziłem, że działa. Zarówno Silverlight jak i Flash 12 odtąd działa elegancko. Przynajmniej do oglądania filmów i transmisji na żywo. Obsługa kamerki w tej "wersji" Flasha nie działa.

by Gabrys

To let others use this knowledge every half a year a note like this is written onto my blog.

Installation

You can read about installation LiveCD issues in a separate blog post. Let's concentrate on things specific to Sony Vaio (mostly the dual-graphics system we have from Sony).

Let's just say it's much better to install Ubuntu using the Intel graphics (the graphics-card switch in STAMINA position) card, since it's supported much much better by Linux.

Installing nVidia drivers

This should be easy, but is not due to a few glitches. Let's get through them step by step:

1. Have the Ubuntu installed using Intel graphics card (STAMINA mode)
2. Stop the laptop
3. Put the graphics-mode switch to SPEED mode
4. Start the laptop again
5. Wait till you can log in
6. Log in. You won't be able to use the Unity desktop, so classic Ubuntu desktop should be launched (if not, choose "Classic Ubuntu (no effects)" from drop-down list when logging in)
7. Click System » Administration » Additional drivers
8. Choose recommended driver and click enable. This will download and install the nVidia drivers for you.
9. Don't reboot yet. You need to blacklist the nouveau driver (it's the open-source 3D nVidia driver attempt). Do this:
   echo blacklist nouveau | sudo tee /etc/modprobe.d/blacklist-nv.conf
10. OK. Now you can reboot. The nvidia driver should kick in and you should have working Unity desktop

One more thing. Intel 3D drivers are now broken, so you won't have the Unity desktop working in there. Let's fix it!

Make 3D graphics (and Unity desktop) work in both Intel and nVidia

This is basically the same as explained in the previous post, but using separate script (so it's more elegant).

Create executable file /usr/local/bin/detect-gl :

sudo touch /usr/local/bin/detect-gl sudo chmod +x /usr/local/bin/detect-gl

Edit it:

sudo gedit /usr/local/bin/detect-gl

Put the following into it:

#!/bin/bash if ls -l /etc/alternatives/gl_conf | grep nvidia; then link=nvidia else link=mesa fi if lspci | grep 'VGA compatible controller: nVidia Corporation'; then hw=nvidia else hw=intel fi if [ "$link" = "nvidia" -a "$hw" = "intel" ]; then update-alternatives --set gl_conf /usr/lib/mesa/ld.so.conf ldconfig killall Xorg fi if [ "$link" = "mesa" -a "$hw" = "nvidia" ]; then update-alternatives --set gl_conf /usr/lib/nvidia-current/ld.so.conf ldconfig killall Xorg fi

Call that script from /etc/rc.local (commands from this script are launched on each boot). Open file /etc/rc.local:

sudo gedit /etc/rc.local

before exit 0 line, put the following line:

/usr/local/bin/detect-gl

Your whole file should look more or less like this:

#!/bin/sh -e # # rc.local # # This script is executed at the end of each multiuser runlevel. # Make sure that the script will "exit 0" on success or any other # value on error. # # In order to enable or disable this script just change the execution # bits. # # By default this script does nothing. /usr/local/bin/detect-gl exit 0

This script will make sure the proper GL library is used for both graphics cards (Mesa lib for Intel, nVidia lib for nVidia card).

Fixing nVidia backlight issues

This is the most elegant solution I could think of. As the brightness settings almost work (when you press the Fn-F5, Fn-F6 keys, the notification appears and the bar shows you the backlight changes) we'll use D-Bus to listen for backlight change signal to set the backlight using nvclock command.

Install nvclock:

sudo apt-get install nvclock

Now create executable file:

sudo touch /usr/local/bin/nvidia-brightness-helper.py sudo chmod +x /usr/local/bin/nvidia-brightness-helper.py

Edit it:

sudo gedit /usr/local/bin/nvidia-brightness-helper.py

Put the following into it:

#!/usr/bin/env python import dbus, gobject from subprocess import call from dbus.mainloop.glib import DBusGMainLoop def apply_brightness(new_brightness): if new_brightness < 15: new_brightness = 15 call(['nvclock', '-S', str(new_brightness)]) # only launch when nVidia is present if call(['bash', '-c', 'lspci | grep "VGA compatible controller: nVidia Corporation" 1>/dev/null']) == 0: dbus.mainloop.glib.DBusGMainLoop(set_as_default=True) bus = dbus.SessionBus() bus.add_signal_receiver(apply_brightness, dbus_interface="org.gnome.PowerManager.Backlight", signal_name="BrightnessChanged") loop = gobject.MainLoop() loop.run()

Now open your Startup programs configuration dialog and add the script to things started when you log in.

Fixing suspend

I must confess I haven't check the suspend without doing this but suspecting it IS broken like in was in Maverick, I've blacklisted the TPM modules by putting:

blacklist tpm blacklist tpm_bios blacklist tpm_tis blacklist tpm_infineon

into /etc/modprobe.d/blacklist-tpm.conf file.

Poor 3D performance

When running Unity all the 3D games have poor performance. I found the easiest workaround is to log in into Classic Ubuntu (with no effects) desktop, which gives you standard GNOME with no compiz and nice 3D performance for launched apps.

Dual-screen issues

I'm using a dual-screen setup (laptop's LCD + external monitor connected via VGA port). The current version of Ubuntu has multiple issues with this, especially when aligning the screens in vertical (laptop's screen being the bottom one, big LCD the top one). The "dock" or "launcher" if you wish appears on the wrong screen (the small laptop instead of on the big screen). To fix this do this:

xrandr --output VGA1 --primary

Log out and in again after doing this. Launcher is on top screen now :-).

I found another irritating bug: when you plug in a big external monitor into the VGA port, the desktop automatically expands to both monitor (not a bug yet), but on one or both of them, some area is black, so you can't see the menus and windows. Logging out and in is also a workaround for this.

When you log in with an external monitor connected, the desktop is strangely stretched and has some artifacts. Interestingly taping Super button (to show the Ubuntu Dash) and Escape (to hide it) refreshes the screen and it looks OK then.

It's hard to put some windows on the bottom screen (your mouse pointer stops on the bottom of the top screen while dragging). You can move the windows even further down using Alt and dragging by window content (and not the title bar).

Once a window is on the bottom screen, trying to resize it crashes the application and it disappears… The workaround is to resize by holding Alt key and drag with middle mouse button.

Other issues

When using Intel graphics card and Unity, Adobe Flash movies (YouTube for example) shows some artifacts. From time to time they also crash the whole X session (I'm not sure why).

OK, this would be it. Hope this helps someone.

by Gabrys

As I had no more CDs or DVDs, I decided to try booting the distribution from USB drive that I assembled from microSDHC card reader and a microSD 4GB card that I got with my Android phone using standard Ubuntu tool called "Boot disk assistant", which burns CD ISO file onto a USB drive in a way that it becomes bootable equivalent of the CD with additional option to save the modifications you make to the Live system on the disk itself, so that it becomes more or less persistent.

LiveUSB creation

First I decided to use that option and let the program use about 3 GB for the overlay file. This made the program busy for about a half an hour, the card reader (actually writer) got warm, and the result was the USB was not that bootable.

A day after that attempt I decided to give it a try without the persistence and it worked this time. The problem came when I tried to "Try Ubuntu" (in opposite to "Install Ubuntu"). The graphic mode quited and I got nothing in return. I tried multiple things to do in text mode, rebooted a few times and after that it appeared that the graphic mode re-run after about a minute. The CPU was completely idle in this time as was the disk, so this wasn't reasonable thing.

Anyways it appeared the release was much more stable than the beta version I tested and it kind of even worked. I found a few concepts useful and cool, so I decided to put the system on my disk to give it a serious try.

Having it on disk

Automatically detecting an external monitor was the biggest positive surprise for me. This never worked in Ubuntu till now. The downside is the graphics got crazy and displayed desktop in not really usable chunks, but I moved some windows around and it got fixed.

nVidia troubles

Then I tried booting with nVidia graphics card enabled (I have a dual-graphics Sony Vaio laptop) to see if the drivers would automatically install. Ubuntu first booted into classic Ubuntu mode (no fancy Unity desktop shell) but it was usable. I navigated to System » Administration » Additional Drivers and chose the recommended proprietary nVidia drivers to install. They got installed and I was asked to reboot the computer so I did.

After the reboot graphic mode was not working and so didn't the text mode. I rebooted with Intel graphics card to discover that installing the nVidia drivers broke Intel drivers which made me without Unity desktop shell even on previously working Intel card. Since I knew what to do to "fix" nVidia I did this — I blacklisted the nouveau module and also a bunch of tpm modules that prevented from proper resume after suspend in previous version of Ubuntu. And rebooted with nVidia card chosen.

This time Xorg went up, the Unity showed up and everything was more or less OK. After removing nVidia drivers (apt-get remove nvidia-current) Intel got working Unity back. But I wanted to have Unity working on both graphics card without constant installing and uninstalling nVidia drivers and I figured out how to do it.

Automating Intel/nVidia boots

In /etc/rc.local before exit 0 I entered something like this:

if ls -l /etc/alternatives/gl_conf | grep nvidia; then link=nvidia else link=mesa fi if lspci | grep 'VGA compatible controller: nVidia Corporation'; then hw=nvidia else hw=intel fi if [ "$link" = "nvidia" -a "$hw" = "intel" ]; then update-alternatives --set gl_conf /usr/lib/mesa/ld.so.conf ldconfig killall Xorg fi if [ "$link" = "mesa" -a "$hw" = "nvidia" ]; then update-alternatives --set gl_conf /usr/lib/nvidia-current/ld.so.conf ldconfig killall Xorg fi

This code checks whether current GL implementation is nVidia (valid for nVidia card) or Mesa (valid for Intel card), then checks current card by examining the output of lspci command and uses certain update-alternatives lines followed by ldconfig to update the GL implementations. killall Xorg kills the X server which is brought back by login manager with GL library updated.

This is a dirty hack but it works just well for me and made both graphic cards working with no additional work.

Glitches/Summary

Ubuntu seems very stable now, but X server crashed a few times (especially loading Flash videos from Vimeo in Firefox). There are some problems in multi-monitor configurations, like no way to move the window to bottom monitor (if they are aligned vertically) by dragging its top bar (moving with Alt works). The windows on bottom monitor are not maximized properly (they are maximized on the top monitor instead) and they can't be resized by dragging the resize handles (but resizing with Alt+middle mouse button works).

There were some other small random issues, either not really relevant or easily fixable, but overall it seems a very good beta release. But wait. This is no beta, but final release. In this case it's not good. It's OK for a Linux user like me, but it definitely should not be released for regular users. Shame on you Canonical. They promised they release in April, but they should have release another beta release, do a serious testing (what I did was anything but unusual), fix the remaining bugs and then release the final version.

by Gabrys

The problem with this router is that there was no cool open source software for it. Linksys opened its sources, but I meant something like DD-WRT or OpenWRT. The problem is that the CPU architecture is different from for example the widely known and used WRT54G series.

Nonetheless there was some heavy work done to run a custom Linux firmware on it. After some successes, the author decided to port OpenWRT distribution to this router. And this is how it's done :-).

The OpenWRT is a command-line distribution of Linux for a bunch of routers. There is a web interface called X-Wrt which is installable as a opkg package to the OpenWRT systems, but there is no real information of how to install it on specifically WRTU54G-TM.

The good news is it can be done, the bad news is you have to hack it a little (but only very little). So let's go.

First, you need to "update" the software of the router to the OpenWRT version. The reference here is: http://wiki.scottn.us/wrtu54g-tm. Just log in to the router WWW interface, select Administration » Firmware Upgrade and choose this file wrtu54g-tm-openwrt-devel-b5.bin (download it from http://wrt.scottn.us/wrtu54g-tm-openwrt-devel-b5.bin).

This takes a while. Router then reboots. Give it a few minutes to load and install. After that the power LED keeps blinking which is probably a bug (in the official firmware, the LED blinks while the system is loading, but once it's up it lights still).

Connect to one of 4 Ethernet ports and you should be given an address IP in the 192.168.1.* network. If not, assign yourself one (for example 192.168.1.10). Then you can confirm the router is up, by pinging it:

ping 192.168.1.1

Trying to ssh to it will reveal you can't really do it, since you don't know the root password. This is tricky, but you need telnet to the router:

telnet 192.168.1.1

You'll be given the root shell. Set the password:

passwd

You'll need to enter the password twice for confirmation. Don't forget it :-).

Now you can ssh to the router:

ssh root@192.168.1.1

Deal with the RSA "host not known" warnings etc, and supply the password you just set.

If you connected the router to the network (by Ethernet cable to the "Internet" port) and your ISP has DHCP server, you should already have the Internet connectiong:

ping google.com

If you need to supply the static IP address, edit the following file:

/etc/config/network

You can use vim (busybox version) editor:

vim /etc/config/network

wan network corresponds to the Internet connection, while lan to the 4-port switch.

In this scenario it's possible you also have to supply the DNS servers, so instead of checking the Internet connectivity by pinging google.com, ping some IP address, like:

ping 8.8.8.8

Once you have the Internet connection, you can update the packages repositories, so you can install the X-Wrt interface:

mv /etc/opkg.conf /etc/original.opkg.conf cat > /etc/opkg.conf

Enter the following:

src/gz adm8668 http://wrt.scottn.us/packages src/gz snapshots http://downloads.openwrt.org/snapshots/trunk/brcm47xx/packages dest root / dest ram /tmp lists_dir ext /var/opkg-lists option overlay_root /overlay arch all 5 arch brcm47xx 10 arch adm8668 20

… and press Ctrl-D. Your /etc/opkg.conf file should now contain the lines above. Update the repositories:

opkg update

Install the X-Wrt, which is packed in package named webif:

opkg install webif

Now if you point your web browser to http://192.168.1.1/ you should have a poor 404 page. It seems the permissions of the /www directory are wrong. I just did that to fix the problem:

chmod -R a+rX /www /etc/init.d/uhttpd restart

Now you can log to the Web interface in with your login (root) and password.

You can now play with the router settings using the browser :-). Much simpler.

References:

http://wiki.scottn.us/wrtu54g-tm
http://wiki.openwrt.org/doc/start

by Gabrys

Let's start from the beginning. I'm having a Sony Vaio laptop with dual graphics system. During boot I can switch if nVidia or Intel graphics card is used. While on nVidia card, I didn't encounter any problems but the thing in "Extra Drivers" no nVidia card was detected. I'm not sure, maybe this "automatic" 3rd party driver installation is only activated after a real install.

I really wanted to see the new Ubuntu interface, so I switched to Intel graphics card and rebooted the machine. After a while I was able to "Try Ubuntu", I started the Firefox and then I noticed I don't have a network connection configured, so I clicked the network manager icon, chose my wifi network and tried to enter the password, but this caused compiz to close unexpectedly. Multiple times. After I managed to click "cancel" button the window decorations were gone and keyboard focus was not passed to clicked field, which made my system unusable. The standard shortcut to run command in Ubuntu: Alt-F2 didn't work either.

This was a pretty short test, but not passed at all. Ubuntu 11.04 doesn't deserve beta status, there are stability issues. For example trying to suspend the laptop in nVidia mode (without any commercial drivers) froze it instead so i had to reboot :-(.

by Gabrys

Although things work pretty good, I had to do some tricks to make it work in specific areas.

Broken suspend

It seems tpm* modules (who knows what they are for?) break this. Putting file like this:

# With these modules loaded suspend doesn't work blacklist tpm blacklist tpm_bios blacklist tpm_tis blacklist tpm_infineon

to /etc/modprobe.d/blacklist-tpm.conf (and rebooting) solves the problem for me.

Brightness buttons not working

Run this code in terminal:

while true; do line=`acpi_listen | head -n 1`; if echo "$line" | grep 'sony/hotkey SPIC 00000001 00000010'; then xbacklight -dec 25 -time 0 -steps 1 smartdimmer -d fi if echo "$line" | grep 'sony/hotkey SPIC 00000001 00000011'; then xbacklight -inc 25 -time 0 -steps 1 smartdimmer -i fi done

You need to have smartdimmer and xbacklight package. The keys kind of work now (but quite lamely).

Other stuff

The Ubuntu font is great. I love it. It seems nouveaux driver (for nVidia card) is really good. It supports multi-monitor configuration via xrandr and other standard stuff. Unfortunately you won't get 3D effects (Compiz) with it and you'll need to install nVidia commercial drivers for it.

Consult Sony Vaio SZ Series And Linux for more (mostly old) information.

by Gabrys

Get Unreal Tournament

The most likely version to obtain is UT GOTY (Game Of The Year edition).

Get Installer

Go here:

http://www.liflg.org/?catid=6&gameid=51

There are two installers. Download both using BitTorrent client. For me the one witout "goty" worked.

Run installer like this:

sudo bash /path/to/unreal.tournament_436-multilanguage.run

Probably it won't run, because you don't have GTK 1.2. Bad news, GTK 1.2 isn't even available in system repository. The last Ubuntu version that shipped GTK 1.2 was Ubuntu Jaunty. My favorite trick to get packages from older distros is as follows:

sudo sed s/lucid/jaunty/g /etc/apt/sources.list -i
sudo aptitude update
sudo aptitude install -y libgtk1.2
sudo sed s/jaunty/lucid/g /etc/apt/sources.list -i
sudo aptitude update

Try to run the installer, it should work now.

Default options are generally OK, so you can keep them. Once "enter CD" dialog appears, you need to either enter the CD or mount the ISO image using the following command:

sudo mount /path/to/the/iso-file.iso /media/cdrom

Click OK, and the installer continues to run. If you're asked to enter CD2 and you don't have one, try the second installer (the one without "goty") from loki site.

Running UT

I had no luck in running UT:

quake@vaio ~ $ ut
Signal: SIGIOT [iot trap]
Aborting.

From this thread I've learned it could be solved by doing this:

cd /usr/local/games/ut/System
for i in ../Maps/*.uz ; do sudo ./ucc-bin decompress $i ; done
mv *.unr ../Maps

After doing this, you should be able, to run ut successfully.

Changing resolution

I was not able to change resolution (once I changed it, it was going back to 640x480 after a few seconds). Open file ~/.loki/ut/System/UnrealTournament.ini, locate "640" and "480" in it and change to desired resolution.

High speed

When I run UT it seemed going about 5 times faster than it should. After reading much about -cpuspeed option and playing with CPU downclocking I figured out that without sound it runs OK. After some experimenting it seems, that it's pulseaudio is causing it, once I killed it and prevented to run (it auto-respawns for some reason) UT finally worked at good speed.

sudo chmod -x /usr/bin/pulseaudio
killall pulseaudio
ut

The problem with this is that some process continuously tries to run pulseaudio, which causes CPU to be loaded and ut to run not smoothly.

So this should work:

sudo mv /usr/bin/pulseaudio /usr/bin/pulseaudio.original
echo -e '#!/bin/bash\nsleep 10000' | sudo tee /usr/bin/pulseaudio
sudo chmod +x /usr/bin/pulseaudio
killall pulseaudio
ut

Remember to do this after playing ut:

sudo mv /usr/bin/pulseaudio.original /usr/bin/pulseaudio

If you have some problems with sound after playing UT, log out and in again, and it should be OK.

NOTE: this trick should be equivalent to running pasuspender ut, but for some reason it does not work.

More tricks

When playing on LAN party we discovered more tricks:

To let UT correctly determine CPU speed, you need to set CPU frequency (using some applet or cpufrequtils) and disable additional cores (leaving one):

echo 0 | sudo tee /sys/devices/system/cpu/cpu1/online
echo 0 | sudo tee /sys/devices/system/cpu/cpu2/online
echo 0 | sudo tee /sys/devices/system/cpu/cpu3/online
echo 0 | sudo tee /sys/devices/system/cpu/cpu4/online
echo 0 | sudo tee /sys/devices/system/cpu/cpu5/online
echo 0 | sudo tee /sys/devices/system/cpu/cpu6/online
echo 0 | sudo tee /sys/devices/system/cpu/cpu7/online

(if you have 8 cores, cpu0 will be online, the rest offline).

Next trick is disabling desktop effects or window composing. For one person this meant much smoother graphics, for other it meant working sound (which is very weird, but yes, that's true).

UPDATE: Maverick Audio

It seems that on maverick the pulseaudio hack is not working, but here's what you can do instead:

• edit /usr/local/bin/ut (may be located somewhere else, find when you installed the game)
• find this line: ./$GAME_BINARY "$CMD_ARGS" "$@"
• replace with: padsp ./$GAME_BINARY "$CMD_ARGS" "$@"
• (make sure you have the padsp binary, just run try to run it)
• then just run ut and sound works :-)

UPDATE: this works, but gives significant audio lags (200-300 ms!). This basically sucks. So the other workaround is:

• having alsa-oss installed (program aoss)
• having a proper .asoundrc in home directory:

ctl.!default { type hw card 0 } pcm.dmixer { #this virtual device does the mixing of type dmix #the various signals ipc_key 1024 slave { pcm "hw:0,0" period_time 0 period_size 1024 buffer_size 4096 rate 44100 } bindings { 0 0 1 1 } } pcm.!default { #this means that applications use the mixer type plug #by default, so you can hear everything slave.pcm "dmixer" }

• having 32 bit alsa-oss libs installed (getlibs -p alsa-oss)

You need /usr/lib32/libaoss.so. Once you have it backup /usr/lib/libaoss.so and link it to the 32 bit version: /usr/lib32/libaoss.so. Then edit the ut script like before but instead of padsp use aoss. This works for me. WARNING: this overrides all ALSA applications. If you want the default configuration (that routes the audio to pulseaudio), you'll need to change .asoundrc file name after playing UT.

by Gabrys

But from time to time you just simply rm -Rf ~ and your all precious data is totally out of luck. Backups you say, don't you?

So let's think how do you do backups. cp /home/quake /my/distant/location ? On my 24 GB home directory? It would take hours. cp /home/quake /home/backups/quake/date ? Better, this will take a few minutes, but wait, I have like 120 GB of disk space, which means I can have no more than 5 backups.

What to do with this? There are two posibilities. Either you minimize data to backup to only backup important data (but figuring out what data is important may take some time and be inappropriate) or move to smarter solution, like incremental backups. Or snapshots.

Having brtfs as the filesystem for my home directory, I chose to make a snapshot of it each hour. It takes between 0 and 1 second to complete and uses almost no disk space. Why? Btrfs is copy-on-write filesystems, which means cloning a filesystems is instant as it only makes it available under two locations. And then modifying one of the two makes a real copy of the modified fragment of it and changes that copy.

OK. How to do it.

First create a btrfs filesystem (you'll need a recent kernel and btrfs-utils):

# mkfs.btrfs /dev/sda7

(sda7 is partition for my /home directory)

Then mount it somewhere else than /home, let's use /vol as an example:

# mount /dev/sda7 /vol

Create some volumes on that filesystem: home, quake, snapshots:

# btrfsctl -S home /vol # btrfsctl -S quake /vol # btrfsctl -S snapshots /vol

The volumes are accessible as the subdirectories of /vol:

# ls -la /vol drwx------ 1 root root 36 1970-01-01 01:00 . drwxr-xr-x 24 root root 4096 2009-10-25 15:04 .. drwx------ 1 root root 20 2009-10-25 15:51 home drwx------ 1 root root 11488 2009-10-25 16:17 quake drwx------ 1 root root 76 2009-10-25 15:40 snapshots

But you can mount then separately:

# mount /dev/sda7 /home -o subvolume=home # mkdir /home/quake # mount /dev/sda7 /home/quake -o subvolume=quake

Fix permissions:

# chown quake:quake /home/quake /vol/quake /vol/snapshots # chmod 0755 /home/ /home/quake

Now you're ready to do snapshots. Now populate the /home/quake directory:

$ mkdir /home/quake/abcd $ mkdir /home/quake/dddd $ mkdir /home/quake/abcd/eeee $ echo testtest > /home/quake/testfile

Aaaaaand, make snapshots!

$ btrfs -s /vol/snapshots/quake-`date +%Y%m%d-%H%M` /vol/quake

I figured out, that it's quite important to point to /vol/quake and not /home/quake. At first it seams that it's totally the same, but on /home/quake there can be some other filesystems mounted (like .gvfs for GNOME virtual file systems) and /vol/quake contains "pure data". When doing snapshots of /home/quake with filesystems mounted under it, the filesystems freezes for me (btrfs is still experimental, they say). So as noted above, it's better to snapshot pure data directory.

Now, the /vol/snapshots/quake-20091025-1653 (or whatever your date is) and /vol/quake should list the same files and the operation of "cloning" should be just instant no matter how much data you have. But now modifying the contents of /vol/quake should not change anything in /vol/snapshots/quake-20091025-1653 (but of course should in /home/quake).

Also the snapshot doesn't really take any disk space as long as you keep the /vol/quake directory unchanged. Once you change some file from /vol/quake, it needs to really keep two copies of it, so this is when additional space is allocated.

To sum up let's have a table listing possibilities to have the same contents in two directories:

More notes on btrfs and snapshotting:

• What can be done with btrfs-bcp on directories level can be done with snapshots on volumes level (as described in this post)
• Snapshots in btrfs are not removable yet. You can clear them and reclaim the space taken by saved difference from the starting point. Still a few bytes is taken by having the directory that is not removable. Deleting snapshots is to be implemented in stable version of btrfs.

by Gabrys

06:00.0 Network controller: Intel Corporation PRO/Wireless 4965 AG or AGN [Kedron] Network Connection (rev 61)

I had problems since late Hardy or Intrepid, using different kernel from that time with no luck. The worst case was connecting to WPA2 Enterprise (user/password) secured network. In worst subcase, I had the connection for 5-20 minutes and after that the network card or driver hanged and then only computer reboot used to help.

I was used to see iwlist scan errors like "Resource temporarily unavailable" or "Busy". dmesg showed different things on different kernels.

My frustration was great, when the problem started (after some upgrades that meant to improve things) to appear even on unsecured network. The connection was broken and I had to notoriously reconnect with my NetworkManager.

Finally I found a version of kernel that plays well.

It's from jaunty-proposed repository (enable it in your Synaptic or other package manager). Don't use jaunty-backports (this one was only broken). The package that solves things is: linux-backports-modules-jaunty version 2.6.28.12.16. The install should also update the linux-image to 2.6.18-12 (update your grub.conf as usual to include the changes).

After rebooting, run uname, to verify the kernel version:

# uname -a Linux vaio 2.6.28-12-generic #43-Ubuntu SMP Fri May 1 19:31:32 UTC 2009 x86_64 GNU/Linux

This is crucial here: 2.6.28-12-generic. The original Ubuntu kernel is 2.6.28-11 not -12.

Hope this helps someone (with VAIO SZ or any other Intel AGN-enabled notebook with Ubuntu).

by Gabrys

First of all, this is a link to the article I've found and seems to be quite OK: http://howtoforge.com/linux_lvm_snapshots_p2

The idea is simple. We have to:

1. Have LVM partition
2. Set up some (I believe this is not limited to standard ext3) partitions on it
3. Prepare some place for backups (over network or on a separate disk)
4. Then at any time, we can just create a snapshot - this does not really consume MUCH resources — but consumes SOME.
5. This takes not more than 1 second and creates a device/file/something that is an image of the filesystem in the exact moment of creating the snapshot.
6. Having the image (snapshot) we can do anything with it (like with a block device) — mount (and backup the files), create a raw-copy, export to another machine, clone, whatever.

Notes

• The author believes one can safely restore a backup without even restarting services.
  • Will we need to rely on this? 60 seconds of down-time is acceptable and guaranties that nothing bad happens.

by Gabrys