![Jesper Juhl](/assets/img/avatar_default.png)
Update ksymoops related documentation to reflect current 2.6 reality. Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
75 lines
2.9 KiB
Text
75 lines
2.9 KiB
Text
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If the box freezes hard with bttv ...
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=====================================
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It might be a bttv driver bug. It also might be bad hardware. It also
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might be something else ...
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Just mailing me "bttv freezes" isn't going to help much. This README
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has a few hints how you can help to pin down the problem.
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bttv bugs
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---------
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If some version works and another doesn't it is likely to be a driver
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bug. It is very helpful if you can tell where exactly it broke
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(i.e. the last working and the first broken version).
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With a hard freeze you probably doesn't find anything in the logfiles.
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The only way to capture any kernel messages is to hook up a serial
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console and let some terminal application log the messages. /me uses
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screen. See Documentation/serial-console.txt for details on setting
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up a serial console.
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Read Documentation/oops-tracing.txt to learn how to get any useful
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information out of a register+stack dump printed by the kernel on
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protection faults (so-called "kernel oops").
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If you run into some kind of deadlock, you can try to dump a call trace
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for each process using sysrq-t (see Documentation/sysrq.txt).
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This way it is possible to figure where *exactly* some process in "D"
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state is stuck.
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I've seen reports that bttv 0.7.x crashes whereas 0.8.x works rock solid
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for some people. Thus probably a small buglet left somewhere in bttv
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0.7.x. I have no idea where exactly, it works stable for me and alot of
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other people. But in case you have problems with the 0.7.x versions you
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can give 0.8.x a try ...
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hardware bugs
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-------------
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Some hardware can't deal with PCI-PCI transfers (i.e. grabber => vga).
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Sometimes problems show up with bttv just because of the high load on
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the PCI bus. The bt848/878 chips have a few workarounds for known
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incompatibilities, see README.quirks.
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Some folks report that increasing the pci latency helps too,
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althrought I'm not sure whenever this really fixes the problems or
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only makes it less likely to happen. Both bttv and btaudio have a
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insmod option to set the PCI latency of the device.
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Some mainboard have problems to deal correctly with multiple devices
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doing DMA at the same time. bttv + ide seems to cause this sometimes,
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if this is the case you likely see freezes only with video and hard disk
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access at the same time. Updating the IDE driver to get the latest and
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greatest workarounds for hardware bugs might fix these problems.
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other
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-----
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If you use some binary-only yunk (like nvidia module) try to reproduce
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the problem without.
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IRQ sharing is known to cause problems in some cases. It works just
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fine in theory and many configurations. Neverless it might be worth a
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try to shuffle around the PCI cards to give bttv another IRQ or make
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it share the IRQ with some other piece of hardware. IRQ sharing with
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VGA cards seems to cause trouble sometimes. I've also seen funny
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effects with bttv sharing the IRQ with the ACPI bridge (and
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apci-enabled kernel).
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