Posts tagged with “resolution”

Sat 15 Aug

Migrating iTunes to New OS

I recently switched from Vista to Ubuntu/Win7 due to truly abysmal performance. We're talking file copy rates in the tens of kilobytes, folks. Bad stuff. Anyway, I have switched over to a much better setup and am getting the kind of performance I am supposed to for the hardware I have. That said, I needed to move over my iTunes library to my new machine, without reimporting everything and losing all my playcount information.

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Thu 26 Feb

Roomba iCreate Unresponsive with Player/Stage

I am working on a research project that uses an iCreate, the hacker's version of the Roomba. It's a nice litle platform, particularly when you extend its functionality with Player/Stage. We have a laptop mounted on top of the robot, which gives us a lot of flexibility with what we can do with it. However, until recently, we'd been seeing some very erratic behavior from the robot.

Scenario: iCreate plus Command Module running Player/Stage 2.1.2, connected via USB-to-serial cable from a laptop to the robot's serial port. Player runs fine and properly accepts clients (such as playerjoy). However, the robot seemingly randomly will stop responding to input from client programs, apparently getting "stuck" on the last command you gave it.

Solution: The problem is actually the command module. For some reason, even when the command module is turned off, the robot exhibits this strange behavior. Removing the Command Module resolved the problem for us.

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Mon 23 Feb

Dell PowerEdge T300 SAS RAID and FreeBSD

I spent a couple hours tonight tackling this problem so I thought I'd post a solution here in case anyone else runs into it.

Scenario: Performed a clean install of FreeBSD7.1-RELEASE on a Dell PowerEdge T300 server with a SAS RAID controller, which completed without errors. After rebooting and beginning to install packages, I started seeing the following error: mpt0: QUEUE FULL EVENT: Bus 0x00 Target 0x00 Depth 120.

Solution: Searching online indicated that the problem was with support for Tagged Command Queuing in the mpt driver. The output of camcontrol was:

skipper# camcontrol tags da0 -v (pass0:mpt0:0:0:0): dev_openings  255 (pass0:mpt0:0:0:0): dev_active    0 (pass0:mpt0:0:0:0): devq_openings 255 (pass0:mpt0:0:0:0): devq_queued   0 (pass0:mpt0:0:0:0): held          0 (pass0:mpt0:0:0:0): mintags       2 (pass0:mpt0:0:0:0): maxtags       255

I then entered:

skipper# camcontrol tags da0 -N 119 (pass0:mpt0:0:0:0): dev_openings  119 (pass0:mpt0:0:0:0): dev_active    0 (pass0:mpt0:0:0:0): devq_openings 119 (pass0:mpt0:0:0:0): devq_queued   0 (pass0:mpt0:0:0:0): held          0 (pass0:mpt0:0:0:0): mintags       2 (pass0:mpt0:0:0:0): maxtags       255

This second command limited the size of the queue to 119, preventing the error I had seen before. To ensure that this problem wouldn't come up in the future, I added the following line to /etc/rc.local

# Set the devq_openings to 119 to prevent problems with SAS controller camcontrol tags da0 -N 119

Doing this runs the command at every boot, preventing the problem from creeping up in the future.

Additional Related Resources:,-freebsd-7.0-on-dell-1950-td20019090.html

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Mon 15 Dec

Perl Find and Replace

I had a web app that I initially wrote with the bad assumption that short tags would always be enabled. Now that I am older and wiser (regarding PHP, anyway), I realized that short tags are an awful thing to force on people. I needed to quickly find and replace all instances of short tags in my application, so I used these two lines of Perl, which I'm posting here so I can easily find them again.

perl -pi -w -e 's/<\?/<\?php/;' *.php perl -pi -w -e 's/<\?phpphp/<\?php/;' *.php

Because I had used the full <?php start tag in some instances, I had to use the second line as well. Thanks to this site for the clear explaination.

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Sun 9 Nov

lejos, libusb-win32, Vista, and usbhub.sys

I've been doing some robotics development lately with lejos. One of the dependencies for lejos is libusb, or for Windows its port libusb-win32. Unfortunately, this package causes problems on Vista (and from what I've read, WinXP) with the USB hub drivers. The problem manifested itself whenever my laptop was connected to the USB hub, which in my case was the docking station.

Whenever I put my computer into sleep mode, or tried to do a shutdown or reboot, I would get a BSOD, followed by a reboot. Actually, putting the computer to sleep caused a seemingly inexplicable reboot. I suppose the BSOD didn't appear because the screen fades out right before going to sleep (boo on you, MSFT: that's bad design if it stifles the BSOD). In any case, the error message pointed to usbhub.sys.

After noticing this problem even in Safe Mode and after a System Restore, I uninstalled libusb-win32 and the problem went away. This has been reported by several people on the project page for libusb-win32. Unofortunately, the project doesn't appear to be under any further development. Also, for the record, I was using libusb-win32

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