24 February 2007

LCD DHL IBM JFS KDE USB HID

The excitement started a week or two ago when I discovered that my ThinkPad laptop’s internal cooling fan had stopped working. As soon as I did something graphically intense for more than a minute or two, the system would overheat and perform an emergency shutdown.

Fortunately, I have a backup laptop.

Unfortunately, the backup ThinkPad laptop had also developed a fault. The fluorescent backlight for the display was failing. The screen was a curious reddish-purple color, and very dim—unless I turned the brightness up, in which case the backlight stopped working entirely, and everything went black. It also tended to crap out when the machine got warm.

So, I called the IBM hardware support line. The next day, the DHL truck showed up and I was handed a shipping box. I followed the instructions and shipped the dying-LCD laptop, which I figured was the less usable of the two. I enclosed the appropriate paperwork and a short description of the problem. Then, I went back to writing Java.

One day later, the DHL truck turned up again. It was my laptop, repaired. New LCD, and they also upgraded the BIOS while they were working on it.

Next, I installed Kubuntu on the repaired machine. I switched to Ubuntu back in June 2006, and had gotten used to GNOME. Unfortunately, the GNOME developers had subsequently decided it was a good idea to include the Mono runtime as a required part of gnome-desktop, and Ubuntu had made it a required part of ubuntu-desktop.

For those who don’t know, Mono is controversial. It’s a Novell project, and Novell just signed a deal with Microsoft to get permission to use patented Microsoft technology in Novell’s Linux distribution (SuSE). Mono is a reimplementation of Microsoft’s .NET, and it’s widely believed that Microsoft hold many patents that cover .NET.

One theory is that Microsoft is encouraging people to become dependent on Mono now so that they can suddenly threaten patent infringement suits and cripple desktop Linux later on. That might sound a little paranoid, but remember that Microsoft already funded SCO during their lawsuit alleging intellectual property infringement in Linux, so plenty of people are suspicious.

Anyway, I want no part of anything to do with .NET, so I had been planning to switch back to KDE and use Kubuntu once the next major release came along. But, with a newly repaired machine and the prospect of upheaval anyway, I decided I might as well make the switch now.

The next piece of excitement was when I discovered that Kubuntu doesn’t support ReiserFS. Regardless of whether Hans Reiser turns out to be guilty of murdering his wife, ReiserFS is on the way out, as Reiser’s team had stopped improving it in favor of Reiser4; and unfortunately, Reiser4 hasn’t made it into the Linux kernel.

So, I had to reformat the entire drive. After some research I decided to go with JFS. (Hey, it’s IBM dog food.) I soon had Kubuntu up and running.

Next I had to move my data over. I tried the direct approach, connecting the two laptops via ethernet and transferring my files over that. After a few minutes the first laptop overheated and shut down. Uh-oh.

I had a fairly recent full backup, so I restored that on the Kubuntu system. I then left rsync running overnight, at nice 19, with a bandwidth limit imposed. This got everything up to date slowly enough to avoid overheating.

Installing Java, Eclipse, VMware and IBM’s VPN software was next. Unpleasant, but it was done soon enough. I logged in and swapped the laptops, putting the newly repaired one on the desk and plugging in the external keyboard and trackball via USB.

Which is when things got really ugly.

The symptoms were unsubtle: the arrow keys, Insert, Delete, Home, End, Page Up and Page Down would all open Ksnapshot every time I pushed one of them. Investigating further with xev revealed that those keys were generating a spurious “release key with keycode 111” event after each pair of correct events. No “push key with keycode 111” event was being generated, but that didn’t seem to matter.

I investigated various possible fixes involving xmodmap. I tried unloading the USB HID kernel modules and seeing if X could handle the USB keyboard as an explicit second keyboard. Nothing worked.

Then, as I was staring at the output of lsmod, I had a vague recollection about UHCI and OHCI and EHCI and USB devices and incompatibilities… On a whim, I tried unplugging the keyboard from the USB hub, and plugging it directly into the laptop. Suddenly everything worked.

So it seems there’s some lingering bug in Linux’s USB keyboard support, which is triggered by USB keyboard converters. My guess is that when the keyboard is plugged into the hub, the incoming USB signals are converted to USB 2.0 by the hub, whereas when the keyboard is plugged directly into the laptop everything is done using USB 1.x. Perhaps the buggy module is only used for USB 2.0.

Actually, there’s one last lingering problem… if I type Shift-Insert the system goes insane, launching dozens of Ksnapshot windows. So I think I need to get a genuine USB keyboard. In the mean time, I’m making a mental note not to type shift-insert, which I don’t usually do anyway as most programs recognize the more usual Ctrl-P for paste.

© mathew 2017