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