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On Tuesday 20 September 2005 16:59, Mark Knecht wrote: |
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> However, if at this point I try to stop the jack server from within |
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> QJC the machine locks hard and only a reset button push gets it going |
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> again. |
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Dragging this thread further off-topic, did you know about the Magic SysRq |
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option? |
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|
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If you have the option enabled in the kernel (Kernel hacking -> kernel |
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debugging -> Magic SysRq key), you can give the kernel a few really useful |
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comands, usually even if there's a runaway process blocking everything. |
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|
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see /usr/src/linux/Documentation/sysrq.txt for more details but here's the |
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basics: |
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To activate a Magic SysRq function, press |
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Alt + SysRq (Print Screen) + the key corresponding to the function |
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all at once. |
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|
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If you want to use more than one function, you can hold Alt + SysRq while |
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pressing and releasing several of the operation keys in sequence |
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|
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Handy options include: |
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Name |key| Description |
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----------+---+-------------------------------------------------------------- |
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Nice | n | Reset all processes to normal priorities (i.e. force runaway |
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| | RT tasks to yield the processor |
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----------+---+-------------------------------------------------------------- |
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tErm | e | Send SIGTERM to all processes except init |
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----------+---+-------------------------------------------------------------- |
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kIll | i | Send SIGKILL to all processes except init |
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----------+---+-------------------------------------------------------------- |
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Sync | s | attempt to sync all mounted filesystems (not always possible |
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| | or immediate, especially if other stuff is still hogging the |
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| | system) |
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----------+---+-------------------------------------------------------------- |
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Umount | u | attempts to remount all mounted filesystems R/O (same caveat |
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| | as for Sync) |
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----------+---+-------------------------------------------------------------- |
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reBoot | b | immediately reboot the system. 99.9% as effective as a |
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| | hardware reset button. Just as dangerous. I reccomend trying |
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| | Nice, tErm, kIll, Sync, and Umount before using reBoot. Note |
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| | that even if Sync and Umount do not succeed, reBoot probably |
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| | will, so be careful |
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----------+---+-------------------------------------------------------------- |
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powerOff | o | immediately power off the system (same warnings as reBoot) |
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----------+---+-------------------------------------------------------------- |
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|
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This has gotten me out of a bind several times. |
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