I'm out of the office until 1st August. On 28 Apr 2011, at 20:52, Bryce Harrington <124...@bugs.launchpad.net> wrote:
> Heh, I see my comment about this being a minor annoyance got people > in a > huff. ;-) > > Anyway, as to whether it's a kernel or X problem, it's sort of a bit > of > both. (The best bugs live in the cracks between two codebases.) X > and > the kernel communicate key events as signals rather than via > threading. > And it only handles one signal at a time, so if for some reason the > key > up signal was fired while another signal was being handled (e.g. from > another device in your system) then it can get lost. That's why > hitting > a key a second time (to fire a new up-key signal) makes things work. > The way signals behave is a kernel thing, so this is why it's partly > kernel, partly X. Essentially it's a race condition. For deeper > information see http://ajaxxx.livejournal.com/62378.html > > Really, it sounds like it's an upstream design flaw in X. Ajax > appears > to be thinking that the whole system should be ripped out and replaced > with a threading system. My own experience with threading is that > sometimes the cure can be worse than the disease... threading can be > quite hard to get right and sometimes has nasty side effects. > Needless > to say, such a change is not trivial and not something we'd do at the > Ubuntu distro level - definitely work that needs done upstream. Maybe > Wayland will gain a better system for handling keyboard events, and > that's where efforts today should be directed? Don't know. > > As an aside, you guys are right that there could conceivably be some > rare scenarios where this bug could cause some severe issue like a > stuck > delete key deleting files or whatnot. Maybe some of you have even > experienced something like that. But for the vast majority of cases, > the issue will exhibit itself as extraneous characters when you're > typing documents and some such - definitely a lot less severe than > random GPU lockups or sudden X crashes back to the login screen or > your > monitor suddenly turning tie died. These latter issues are > unfortunately not as uncommon as I'd like, and until they are I tend > to > judge anything less severe as a "minor annoyance". ;-) > > But annoyances are bad. While I don't think this issue is one we're > likely to work on in Ubuntu at the distro level, I can give some > advice > about how to go forward with it, if you're wanting to pursue it > yourself. (And FSM bless you!) > > Due to the nature of the issue, it's frequency and severity are > going to > vary from hardware to hardware. Due to timings in hardware interrupts > and signal generation, and even interactions with software, you might > see it only with a particular combination of keyboard, motherboard, > and > mouse. Or it might go away after turning off your wireless. Or might > go away for 3 Ubuntu releases and then suddenly and quite mysteriously > reappear. Most of our typical keyboard debugging tools such as xev > are > going to be of limited value in investigating it; it may tell you that > the release signal didn't show up, but that doesn't explain why. > There > are kernel debugging interfaces that will show what's going on there, > but that gives limited insights as well. > > The first thing I would look at is obtaining a reliable repetitive > test > case. Get together hardware and a set of steps that lets you reliably > reproduce the issue on command, or with a sane enough frequency (like > steps that let you reproduce >25% of the time). This makes testing > less > time consuming and also gives you a strong way to determine it's > definitely fixed. > > Next, it would be smart to ensure someone hasn't already fixed it. > That > could save you a lot of work. We provide xorg-edgers and kernel > ppas to > facilitate doing this. See https://launchpad.net/~xorg- > edgers/+archive/ppa and http://kernel.ubuntu.com/~kernel-ppa/ > mainline/. > > Finally the hard part, which will require code hacking. Touch base > about this with Ajax to find if he has any experimental branches, or > if > he knows if anyone else is working on the problem, and how you can > help. > From his blog post, it sounds like the implementation of threaded > input > handling might be the real way forward, and that could probably > benefit > from extra testers and/or coders. > > -- > You received this bug notification because you are a member of > Papercutters, which is subscribed to One Hundred Paper Cuts. > https://bugs.launchpad.net/bugs/124406 > > Title: > Keyboard keys get stuck and repeat > > Status in GNU Emacs: > Invalid > Status in One Hundred Paper Cuts: > Invalid > Status in The Linux Kernel: > Confirmed > Status in X.Org X server: > In Progress > Status in “linux” package in Ubuntu: > Won't Fix > Status in “xorg-server” package in Ubuntu: > Triaged > Status in “linux” source package in Jaunty: > Won't Fix > Status in “xorg-server” source package in Jaunty: > Invalid > Status in Gentoo Linux: > New > > Bug description: > Keyboard keys such as the arrows, Alt-F4, PageUp/PageDown, etc. often > get 'stuck' and continue being 'clicked' even after they are > physically released. For example when clicking Alt-F4, sometimes it > gets stuck so all the windows are closed instead of just one. > > My configuration is Feisty + Xgl + Compiz Fusion. My previous > configuration was Edgy + Xgl + Beryl, where this didn't happen. > Others > have reported the same problem without using either Xgl or Compiz. > > The keyboard itself isn't the problem. When dual-booting to Windows, > everything works fine. Also, the problem happens with two different > keyboards (internal laptop, external USB). > > My best guess is that the problem occurs at time of high system load. > Somehow during these times the key-release signal gets lost and the > key-press is repeated indefinitely. This happens more often with > Compiz configurations because Compiz tends to increase system load. > It > also happens more often with power-hungry apps like Firefox and > Acrobat Reader for similar reasons. > > PS: When the keys would repeat all input devices would be locked up. > ie. mouse won't move, clicks don't do anything, keyboard presses > don't > register. Then when it becomes unstuck, the mouse moves around and > everything. Hope this helps. > > See also this forum thread for other people with the same problem: > http://ubuntuforums.org/showthread.php?t=432057 ** Attachment added: "unnamed" https://bugs.launchpad.net/bugs/124406/+attachment/2233544/+files/unnamed -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/124406 Title: Keyboard keys get stuck and repeat To manage notifications about this bug go to: https://bugs.launchpad.net/emacs/+bug/124406/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
