Qt/OpenGL/Ubuntu Bug

This is a discussion on Qt/OpenGL/Ubuntu Bug within the Tech Board forums, part of the Community Boards category; But I think by magic sys key what is actually meant is Alt+PrintScreen (or was it Ctrl+PrintScreen?). It's a very, ...

  1. #16
    Cat without Hat CornedBee's Avatar
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    But I think by magic sys key what is actually meant is Alt+PrintScreen (or was it Ctrl+PrintScreen?). It's a very, very special kernel feature that should allow regaining of some control (enough to do things like kernel dumps) even in the most severe error cases, such as kernel panics or kernel-internal deadlocks.
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  2. #17
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    The link I postet says

    ALT-SYSRQ
    that on most PCs shoul evaluate to alt+print+[key]

    I forgot to mention that this feature must be enabled in the kernel config. But I think I remember ubuntu has it enabled. you can check it this way:
    Code:
    ~ # grep -i magic /boot/config
    CONFIG_MAGIC_SYSRQ=y
    y means "enabled"

    at least it can saves you from coffee-can-long file system checks. not unimportant using a rapidly crashing program / os

  3. #18
    Cat without Hat CornedBee's Avatar
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    File system checks are much faster on the journaled file systems in use nowadays.
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  4. #19
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    Thanks for all the replies. I tried the ALT + SYSRQ + [KEY], and it didn't appear to do anything but run the file system check when I booted it up the next time (it wasn't so long.) The link said ALT + SYSRQ + t dumps all the processes and related information to the console, but it didn't seem to do anything.

  5. #20
    Cat without Hat CornedBee's Avatar
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    You'd probably have to be on a console, but most likely you were on an X server.
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  6. #21
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    try this:

    A:
    switch to terminal (alt+ctrl+f1)
    sysrequest help (alt+print+h)
    if you get a help message goto B, else
    try
    Code:
    echo 1 > /proc/sys/kernel/sysrq
    (as root) and goto A

    B:
    run your crashing app and if it's crashed:
    alt+print+r to regain keyboard access
    alt+print+s to sync files systems
    alt+print+k to kill all processes of the actual virtual terminal -> xserver should die and restart itself)
    ...debug...
    goto B

    does this work?



    Quote Originally Posted by aprescott_27 View Post
    The link said ALT + SYSRQ + t dumps all the processes and related information to the console, but it didn't seem to do anything.
    On my machine alt+print+h prints to a text terminal (alt+ctrl+F1) and alt+print+t dumps to the syslog, not to console.
    Last edited by pheres; 07-12-2007 at 01:37 PM.

  7. #22
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    So I don't think anyone gave information that is technically meaningful. Are there no logs which track errors, or anything of the sort? I mean in -windows- I can refer to the event log to see how applications fail.

    The best response you can get out of me anyway, is that elves magically crapped all over your piece of software.

    More.... -specific- information, or don't post since it's futile. :-)

    And all of you telling him to watch his memory, you're insane. he hasn't said anything that should indicate that's an issue because he hasn't given any useful information other than his assumption, which he says he's assuming.

    So please capture an error message, capture an exception, capture -something- that can be interpreted by someone other than you. Then maybe we can help.

    Step through the application if you have to in debug, and watch it crash. Show us some piece of code where the error may be occurring, we can start small and build up.

  8. #23
    Cat without Hat CornedBee's Avatar
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    There's the kernel log, there's the system log, but they don't seem to contain anything. Which can happen, with some bugs. We're trying to help him in getting information.
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  9. #24
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    Do you have an ATI card and are you using the fglrx drivers by any chance? In the past I've had problems quite similar to yours. If so, you could try using the free ati or radeon driver and see if your problem persists.

  10. #25
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    BTW, this has gone way off-topic. Moving to Tech.
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  11. #26
    l'Anziano DavidP's Avatar
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    Two things:

    1. your friend who ran the program on his machine said he a got a seg fault, but you said you don't really have any pointers in the program. Seg faults are pretty much aways an issue with dangling pointers. One time just recently I was getting a seg fault, but I didn't have a single pointer in my entire program....I fixed it somehow, although I can't remember exactly what the issue was as it was over 6 months ago. My point is, even if you think you don't have any pointers at all...seg faults can still occur.

    2. What video card are you using? I used to have a GeForce 2 and it would stall all the time. It was so annoying...
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