Strange keyboard problem

October 19th, 2007 by Samuel Tardieu

Since about a week, I started to notice that I had been making a lot of typos in some commands I use frequently. For example, I became unable to type correctly

cd /usr/src/linux

which always resulted in

cd /usr/src:linux

(incidentally, when typing the above strings, I had to fix the first one and the second one came naturally buggy)

On a French keyboard (AZERTY layout), / is obtained by pressing shift and :. I first thought that my laptop keyboard was misfunctioning. But it happened on my home computer as well. I then thought I had become unable to properly release the C key before pressing the shift one, but no, I think I found a real bug somewhere: this problem occurs only when a key amongst the lowest left part of the keyboard (near to the shift, namely one of the WXCV letters on my keyboard) is rapidly followed by a shift.

Let’s make a test: while running a X11 server, press the C key, let it pressed so that you turn the auto-repeat mode on, then press shift (without releasing the key). You should, at least under Linux with Xorg, see something like:

ccccccccccccccCCCCCCCCCCCCCCCC...

But what I get is:

cccccccccccccccccccccc...

The shift key is ignored. Note that it works fine with the right shift key though.

For a fast touch typist (as I otherwise luckily am), this is rather unfortunate; the combination of one of those wxcv letters followed by a slash happens to me at least fifty times a day, often much more than that. Since I cannot reproduce that on the Linux console, I will for the moment put the blame on my X server.

5 Responses to “Strange keyboard problem”

  1. JCabillot Says:

    I have the same problem (I’m french too) on some boxes, but I think it depend on the Xorg version, here I have a Xorg 7.3 and cccCCC work perfectly.

  2. Samuel Tardieu Says:

    JCabillot: of course, just after I made this post, I found that some people had the same bug (including you) and that a fix may be working, see this page. I’ll test it.

  3. Thomas Says:

    Some bugs are really fascinating.

  4. Samuel Tardieu Says:

    Indeed, this patch fixes the bug. I’m happy to see that my fingers were not to blame!

  5. Nico XxL Says:

    Bon je suis venu chercher des infos par rapport a nos cours sur mmap() mais je me suis paume et je crois que j’ai trouve une nouvelle facon de genialement (ne pas) perdre mon temps :)

Leave a Reply


Creative Commons License