Ubuntu and Radeon video cards

The last few releases of Ubuntu have given me a lot of trouble on a desktop with a pair of Radeon 7970 video cards. The Live CD would start up, but leave me with a blank black screen and a mouse cursor. Doing a console-only install worked fine, but as soon as I’d try to install an X server, the system would go back to showing nothing more than a black screen.

Various help forums discuss enabling the “nomodeset” option during installation (it seems lots of other folks have had problems getting Ubuntu to play nice with AMD/ATI video cards). By itself, that didn’t make any difference on my system, but the idea in this thread put me on the right track. Here are the steps I used to install Ubuntu 14.04 on a system with a pair of Radeon 7970 graphics cards:

  1. When the Live DVD starts up, press the down arrow. A language selection screen should appear; use the arrow keys to select your language and press Return.
  2. Press F6. A menu will appear with advanced installation options. Check the boxes for “nomodeset” and “free software only” (use the Return key to check them).
  3. Press Escape to exit that menu and press Return to start the Live DVD.
  4. After waiting a few minutes, my system still appeared hung on a blank screen. Press ctrl-alt-F1 to get to a console.
  5. At the console, enter the command “sudo bash” to start a shell with administrative access.
  6. Type “apt-get remove xserver-xorg-video-radeon” to remove the default Radeon driver.
  7. Type “service lightdm restart” to restart the display manager. On my system, this took me to a regular desktop running from the Live DVD. From there I could install Ubuntu normally.
  8. Once the install finished and the system restarted, I went into Settings → Software & Updates and checked the box to allow “Proprietary drivers for devices”. Close that dialog to apply the new setting, then open it up again. Select the “Additional Drivers” tab and change from the open-source driver to AMD’s fglrx-updates driver. Reboot and enjoy your new Ubuntu desktop.

[Nearly] Silence your Butterfly Labs Little Single Bitcoin Miner

Last week my Butterfly Lab Little Single (SC) Bitcoin miner finally arrived. The good: it works as advertised and mines Bitcoins at about 30 GH/sec. Setup was a breeze on Windows 8; plug in the miner, install the WinUSB driver using Zadig, startup cgminer, and away it goes.

The bad: it runs with all the subtlety of a jet engine. This thing is far and away louder than the eight GPUs I used to have running full-bore minting Bitcoins. Something needed to be done.

I took it apart to see if any improvements could be made. Two problems stood out: the heatsink fan was pointing in the wrong direction, and there was no air intake fan. Rummaging in the closest revealed a pair of Corsair 120mm fans and a 3-pin power splitter, so I already had all the hardware I needed. Flipping the heatsink fan around, replacing the stock exhaust fan with a quieter model, and adding an intake fan took about 10 minutes. The noise coming out of the unit is easily half of what it was; using a cheap iPhone sound meter gave a reading of 60 dB (for comparison, the same meter read 55 dB for a pair of mining GPUs).

Not only is it quieter—it’s also running cooler. Prior to this mod, it ran at about 80° C. Post-mod, it bounces between 68°–70° C. I’ve noticed that when it gets down to 68º the fans spin down further, to the point where it’s nearly silent. When the temp creeps up to 70º the fans spin back up, but still nowhere near the loudness level of the stock cooling solution.

If you want to do this yourself, here’s what you’ll need:

The steps are simple:

  1. Remove the four Torx screws from one end of the unit.
  2. Slide off the casing.
  3. Disconnect the exhaust fan from the 3-pin connector (located in the middle of the unit’s mainboard).
  4. Remove the four Torx screws from the opposite end of the unit.
  5. Remove the two Philips screws from the heatsink fan.
  6. Turn the heatsink fan upside and screw it back onto the heatsink. This fan should be blowing air down onto the heatsink; BFL installed it so that it draws air up and away from the heatsink. (An easy way to test the direction a fan is blowing is to hold a piece of tissue paper over it while it’s running.)
  7. Install one of the 120mm fans as an exhaust fan next to the heatsink (replacing the fan BFL supplied). This should be blowing hot air out of the unit.
  8. Install the other 120mm fan as an intake fan on the other side of the unit (BFL didn’t include a fan here on my unit). This should be drawing cold air into the unit.
  9. Use the 3-pin Y-splitter to connect both fans to the single 3-pin fan connector on the mainboard.
  10. Slide the case back on and screw the end-caps back in place using the Torx screws.

Here’s a photo showing what it should look like (with the case removed). The blue arrows indicate the direction of airflow for each fan.

Improved airflow on the BFL Little Single.

Improved airflow on the BFL Little Single.

It’s not completely silent, but it’s quiet enough for me to run 24/7 now. Thanks to Butterfly Labs for providing excellent Bitcoin mining hardware; I just wish they’d had put a bit more thought into the unit’s airflow. Thankfully, that’s easy to fix on our own.

Cygwin and the Case of the Unreadable Blues

Cygwin includes some nice built-in aliases for colorizing terminal output, but the default blue hue is so dark as to be unreadable on the black background. It’s easy to fix, though; just add the following Blue and BoldBlue lines to your ~/.minttyrc file:


These lines will use a lighter shade of blue than the default, so you’ll be able to read it in a less-than-pitch-dark room. As an example, here’s my complete ~/.minttyrc file:


Hash strings to integers in PHP with the DJB hashing algorithm

I recently found myself needing a PHP implementation of the DJB hashing algorithm, but ran into a problem—in 64-bit PHP5, integers don’t overflow. Instead, they magically turn into floating point variables large enough to hold the new value. For short strings this isn’t really a problem (the hashing algorithm won’t cause an integer overflow in the first place), but for anything over five or six characters, you end up with numbers that aren’t comparable with other implementations of the algorithm (nor, for that matter, will they fit into any of MySQL’s numeric data types).

So, here’s a short function that uses PHP’s GNU Multiple Precision (GMP) module to perform the arithmetic at the necessary level of precision, then convert the result back to a standard PHP int:

define('PHP_INT_MIN', ~PHP_INT_MAX);

function hash_djb2($str){
	$hash = 5381;
	$length = strlen($str);

	for($i = 0; $i < $length; $i++) {
		$hash = gmp_add(gmp_mul($hash, 33), ord($str[$i]));
		while (gmp_cmp($hash, PHP_INT_MAX) > 0) {
			$diff =	gmp_sub($hash, PHP_INT_MAX);
			$hash =	gmp_add($diff, PHP_INT_MIN);
			$hash =	gmp_sub($hash, 1); // off by 1
	return gmp_intval($hash);

I’ve only tested this on 64-bit PHP5 on Linux. PHP seems to handle integers a little differently across different platforms, so your mileage may vary. Enjoy!

iCloud and Outlook: Installation Order Matters!

Nice work, nVidia. Today marks the third time in three years I’ve had to send my Mac back to Apple to replace one of your faulty GPUs. What the hell happened?

I spent the morning setting up an old Windows box so I can at least keep up on e-mail while my Mac gets a less-broken logic board. Figured this would be a good chance to checkout iCloud on Windows, so I downloaded it, installed it, and then installed Outlook 2010. Went into the iCloud control panel, told it to synchronize my Outlook Contacts, and… no. Got this useful error instead:

Error: 0x8004010F: ZebraMapiCopySession::CreateMobileMeMessageStore: CreateMessageService failed

What the hell does that mean? Turns out, it means that you shouldn’t install Outlook after iCloud; you need to install Microsoft Office first. Uninstalling and then re-installing iCloud fixed the problem. Now I’ve got my calendar, contacts, and e-mail all showing up nicely in Outlook. Which would be awesome, except—it’s still Outlook.

And Apple? Your error messages could use some work…

Apple TV and iTunes Match

My 3rd generation Apple TV (with iOS 5) has some problems streaming media. First noticed it with NetFlix; the stream would pause for about 30 seconds every couple of minutes. iTunes Match had a different problem; after playing about 10 minutes of music, the screen would go blank (my TV started searching for different inputs, so I think the Apple TV’s output signal completely died), then return to the Apple TV home screen. I haven’t had any problems using NetFlix or iTunes Match on my computer, so I assumed the wifi (an Airport Extreme) and Internet connection weren’t to blame.

Finally seem to have tracked down the problem (or at least, one of them): it’s something in the Dolby Digital output. Go into Settings/Audio & Video/Dolby Digital and change the value to Off. I have my Apple TV hooked up to a receiver via an optical cable, so I’d turned this setting on to get surround sound. Since disabling, I’ve been able to listen to entire albums on iTunes Match for the first time—they had never made it past the 10 minute mark before. Here’s hoping a software update will fix this issue and restore the surround sound feature…

Update: Spoke too soon—just dropped the audio stream again, though it’s definitely not happening as consistently as before. *sigh*.

iOS 5.1 disabled iMessage

Not sure if anyone else has had this problem, but it looks like yesterday’s iOS 5.1 update turned off iMessage support, at least on my AT&T iPhone 4. A quick trip to Settings→Messages→iMessage was all that it took to get iMessages working again (they had somehow been turned off during the update).

Anyway, just posting in case someone else is trying to figure out why their iPhone suddenly stopped receiving iMessages.

New look!

Finally gave this old site something of a make-over. Most of my energy these days goes into research, art, and music, so I’ve made space for those topics and removed all of the old, long-unloved software projects. They were mostly just gathering bit-dust here, anyway—the successful ones found new homes years ago.

So, if you came here looking for something specific but keep hitting 404′s trying to find it, drop me a line. I’ll point you in the right direction.

Yet Another WordPress Flash Uploader Problem (with solution!)

This was a new one for me. Every time I tried to upload a photo to a WordPress site, I received a very informative “HTTP Error” message while the upload progress bar read “Crunching…”. Thanks in part to the stunningly generic error message, it took a while to figure out exactly what was going on.  The problem, it turns out, was HTTP authentication; I had enabled Apache’s basic HTTP login for the site, but being a plugin, Adobe Flash was not similarly authenticated.  So, trying to use the Flash-based image uploader kept silently failing because it couldn’t authenticate with the server.  The fix is simple: just tell Apache not to use authentication for the script that handles Flash-based uploads.  You can do this by modifying the .htaccess file in the root of your WordPress directory like so:

<FilesMatch "(async-upload.php)$">
    Satisfy Any
    Order allow,deny
    Allow from all
    Deny from none

Making the Apple Keyboard Play Nice with Windows

After a long, long love affair with Logitech, I’ve finally finished a slow migration toward Apple’s input devices.  Their aluminum keyboard took some getting used, but once I’d grown accustomed to it on my Macbook, I decided to get one for my Windows 7 desktop.  It seemed like everything was working perfectly until I pressed the mute button; nothing happened.  Volume down?  No go.  In fact, all of the media keys (volume up/down, mute, play/pause, etc.) refused to do anything. For whatever reason, SharpKeys and other keyboard mapping utilities don’t recognize Apple’s media keys.  The solution, it turns out, is to install a pair of Bootcamp files from your Mac OS X installation DVD.

Here are the steps that worked for me.  I’m running Windows 7 x64 with a 2010 Apple aluminum keyboard, and have a Mac OS X 10.6 Snow Leopard installation disc.  As always, your mileage may vary:

  1. Insert your Mac OS X installation disc.  If it tries to auto-run anything, cancel it.
  2. Open Windows Explorer, right-click on your DVD drive, and select Open from the menu.
  3. Navigate to the Boot CampDriversApple folder.
  4. Copy BootCamp.msi (or BootCamp64.msi for x64 systems) to your desktop.
  5. Copy AppleKeyboardInstaller.exe (or x64/AppleKeyboardInstaller64.exe for x64 systems) to your desktop.
  6. Use a tool such as 7-zip to extract the AppleKeyboardInstaller.exe file.
    1. With 7-zip, can you do this by right-clicking on the file and selecting 7-Zip->Extract to “AppleKeyboardInstaller”.
  7. Navigate to the folder you extracted AppleKeyboardInstaller.exe to and run the DPInst.exe file to install the Apple keyboard driver for Windows.
  8. Click Start->All Programs->Accessories, right-click on Command Prompt, and select Run as administrator.
  9. In the command prompt, type “cd Desktop“.
  10. Install BootCamp by typing “BootCamp.msi” (or “BootCamp64.msi” for x64 systems) in the command prompt.
  11. Once the installation completes, you can delete the files on your desktop and remove the Mac OS X installation disc.  Reboot your computer and enjoy your new media keys!

April 2013 Update: I just tried this method using Windows 8 and the BootCamp drivers from Mac OS X 10.8 Mountain Lion. Apple seems to be preventing the new BootCamp.msi  (version 5) from installing on non-Apple hardware, so the above method will fail on Step 10. Luckily I had an old copy of Mac OS X 10.7 Lion BootCamp drivers (version 4) which worked perfectly on Windows 8.

August 2013 Update: Thanks to Tom in the comments section, who pointed out that Apple’s Bootcamp update will install on non-Apple hardware, so we can use the latest Bootcamp drivers on Windows 8! On my machine, however, these new Bootcamp drivers set the time incorrectly after each reboot. The fix is to open up regedit.exe and navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation. Double-click the RealTimeIsUniversal key and set its value to 0. Reboot and enjoy!