Author: root42

Setting PATH and other variables on OS X

Since OS X is a UNIX like many others, I usually put my environment variable settings like PATH in ~/.profile. However, for Cocoa based apps, that are not run from a terminal, this will not help. Luckily, there is a documented procedure for setting environment variables for Cocoa applications. In short, you just have to edit a plist. If it already exists on your system, just type the following in a terminal:

open ~/.MacOSX/environment.plist
If the file does not yet exist, just run the Property List Editor (e.g. via spotlight), and create that folder and that file.

Syncing iPod Touch and iPhone with Linux

Ok, so I just tried out the new libimobiledevice. Installation was a breeze, using the provided OpenSUSE repository. A first run of ideviceinfo returned successfully detailed information about the attached iPod Touch. I also upgraded libgpod4. But Amarok 2.3 did not show a thing. Mounting of the iPod needed to be done manually using “ifuse ~/my-ipod-dir”. Supposedly, this happens automatically with Gnome, usin gvfs. But since I am using KDE, this is at the moment a no-go. Ok, so Amarok fails at this point in time. What about gtkpod? It works, although it throws some mysterious error message (“Eweiterte Informationen werden nicht verwendet” — wtf?), and that program is dog-slow. I though iTunes is bad, but this program is really, really slow as a snail. But here a proof of concept that I was able to sync to albums to the device:


What I did not yet try is syncing contacts, notes and bookmarks. With gtkpod, you need to specify a program to do that. No idea which one that is supposed to be. Keeping my MobileMe contacts in sync with my Linux desktop would be nice, though. Also, syncing from within Amarok is mandatory for me, but does not work currently. So let’s wait and hope the situation gets better with time. So far I will continue to sync my device with OS X.

Extremely slow SMB performance over WiFi using OS X

I have an OpenSUSE machine running a Samba server to provide files to my network. Now when I use the MacBook Pro to access those files, this happens awfully slow, with 80-200 KiB per second. I never figured out why, since rsync and sftp work very fast (for WiFi at least), at speeds of around 1.2 MiB per second. Today I googled for it, and it turns out that OS X delays ACK packages. I have no clue why it does that and what good this does, but you can disable it by running:

sudo sysctl -w net.inet.tcp.delayed_ack=0
After that, my SMB transfers jumped to 1 MiB per second, minimum. You can presumably make this change permanent by adding “net.inet.tcp.delayed_ack=0” to the file /etc/sysctl.conf. This will then be applied during system startup.
Update: Here is a nice explanation why the performance of OS X suffers sometimes, when using delayed ACK, and also why it might be useful in some cases.

OpenCL on OS X

I have just tried to run an official OpenCL sample program by Apple on a MBP 10.6.3 machine. Result: a crash. Why? I do not know yet, but it seems that OpenCL somehow crashlanded the nvidia OpenGL driver. This is what I get:
08.04.10 17:04:50 kernel NVDA(OpenGL): Channel exception! exception type = 0xd = GR: SW Notify Error
08.04.10 17:04:50 kernel 0000006e
08.04.10 17:04:50 kernel 00200000 00008397 00000474 00000040
08.04.10 17:04:50 kernel 0000047e 00001408 00000001 00000008
08.04.10 17:04:50 kernel 00000000 00000000 01dfdc03
08.04.10 17:05:04 kernel NVDA(OpenGL): Channel exception! exception type = 0x8 = Fifo: Watchdog Timeout Error
08.04.10 17:05:04 kernel 0000006e
08.04.10 17:05:04 kernel 00000010 00008397 00000474 00000000
08.04.10 17:05:04 kernel 0000047e 00001528 00000000 00000008
08.04.10 17:05:04 kernel 00000000 00000000 019fdc03
As soon as I know something more and especially how to fix it, I will share it here.
Update: It does not crash, if I don’t touch any keys when the kernel runs. So I guess the OpenCL drivers are a bit buggy still…

SD card reading problems

Today I was shooting some pictures using some camera and a cheap 2GB SD card. Upon returning home, I copied the pictures from the SD card to the Mac, using an old 6-in-1 card reader. After about 980 MiB of images, OS X throws a read error. Using cp in terminal yields the same result. Trying to repair the card using the hard disk utility even resulted in the system hanging. No hard freeze, but I had to power cycle it, since I was too lazy to fire up another ssh-capable machine.
After some research, I read on Wikipedia that SD cards over 1 GiB are adressed differently. It seems that older devices, such as my reader may have problems using those cards. This means I have to go buy a new reader tomorrow, I guess! Or be restricted to using only 1 Gig of the SD cards I use… Which is not a good idea for camera producing 37 MiB RAW files.

Update: My suspicion was correct. A new 10 € card reader solved the problem. The 2 GiB are back, I can read all the photos from the card.