Tech Stuff

Updated: April/12

This page covers interesting “stuff” that I have learned over the years, some of it quiet obscure. Use at your own risk.


Problem: EEE 701, with 512KB of ram, I upgraded easily to 2G of ram (DDR2 PC2-5300). But the Linux kernel that comes with the EEE only uses the first 1G of ram.

Solution: 1) Read this page. Download the kernel. You can test it by rebooting and hit F9 to get the Grub menu. Then edit the first entry, and change the “kernel” line to

kernel (0x80,1)/home/user/vmlinuz- quiet rw vga=785 irqpoll i8052,noloop=1 root=/dev/sda1

Then hit the 'b' key to boot, and see if the kernel will run for you (it will!)

Problem: I updated to Easy Peasy 1.5 on my EEE701. Then my apt sources list seemed really messed up; lots of "invalid signature" messages

Solution: Clear out the /var/lib/apt/lists directory, and then "apt-get clean" and things seem to get cleard up. See:



Problem: I updated my Thinkpad X31 running Kubuntu from Intrepid to Jaunty. I had to change my xorg.conf driver from "ati" to "radeon". Then my X server began to peg the usage meter, consuming 100% of the CPU. Other solutions on the net include: deleting gnome-config, turning off compiz; neither of these helped

Solution: I deleted xorg.conf, and then ran

dpkg-reconfigure xserver-xorg
. I don't know what aspect it changed, but now my X server takes about 2-20% of the CPU, which is fine with me.

Wrong, wrong. That didn't do it. I found the problem though; something in my kde config was causing the X app to chew up the CPU time. When I deleted ~/.kde, the system came up very responsive, with X taking only a tiny fraction of the CPU. Of course, I lost all my app preferences, but that's ok with me.

sigh....wrong again. It turns out that Ubuntu/Jaunty sets the X server driver to use the new EXA (experimental) acceleration mode, which doesn't work on my Thinkpad X31. By adding the line

    Option   "AccelMethod"  "xaa" 
to my /etc/X11/xorg.conf file, this seems to have fixed it. The X server no longer tops the "top" list. Average cpu consumption seems to be <1%.

Problem: My desktop is a M2A-VM, with an RS690/X1200 Radeon chip onboard. The newest (Lucid Lynx 10.04) had problems with complex OpenGL rendering; there were all kinds of surfaces shown where they weren't supposed to be

Solution: The default for Ubuntu 10.4 is to enable kernel mode setting (KMS) for the video. By adding "nomodeset" to the kernel startup (in /etc/default/grub), the video now works. This disables kernel mode setting, and reverts to xorg doing all the mode setting. And my glxgears went from 1400fps to 2400fps.


Problem: I bought a TEW-652BRP router, and was trying to install the DD-WRT firmware on it. It wouldn't go in.

Solution: The TEW-652BRP factory firmware will accept a firmware upload that has the signature for a '652; that is, the binary ends with the phrase AP81-AR9130-RT-080609-05. That's all ok.

But, I had toasted the factory firmware, and had to fall back to the firmware recovery mechanism; the basic trival page. It seems that Trendnet used the code from the '632 at that point. I had to patch the binary so that it ends with AP81-AR9130-RT-070614-00, which is the signature for the '632. After that, all was fine.


Problem: I had a hard time getting the h264 encoding to work. Either the codec is not found. "Unknown encoder"

Solution: It turns out that in recent (2012) versions of ffmpeg, the decoder is called h264, but the encoder is called libx264. And you need to give it a "preset", with either

	-vpre slow
	-preset slow

If those preset names don't work, try looking in /usr/share/ffmpeg at the file names. On my machine, I had to use the entire file name, including any prefix. Here's an invocation of ffmpeg that worked:

ffmpeg -i out-1.ogv -ss 5  -t 45 -r 12 -loop_output 5 -s svga -vpre libx264-slow -vcodec libx264