[mythtv-users] My Perennial Problems with XvMC
chris at cpr.homelinux.net
chris at cpr.homelinux.net
Wed Sep 20 03:37:15 UTC 2006
On Tue, Sep 19, 2006 at 08:05:31PM -0600, Norm Dugas wrote:
> I would check to make sure it's not a bus issue or a shared IRQ issue
> (if you've got AGP and PCI, don't know about PCIe). Mobo docs should
> say something about IRQ assignments. As for the bus issue, google would
> be my friend.
Note that almost all motherboards physically share IRQ lines
between different PCI slots and the mobo resources, so often the
only way to put two devices onto different interrupts is to
physically move the card to a different slot. Changing the IRQ
assignment for one card won't have any effect as the other will
follow it.
For example, on my Asus P4X8X-X the IRQ line assignments are:
IRQ A = PCI5
IRQ B = PCI2 + PCI6 + AGP
IRQ C = PCI3 + mobo audio
IRQ D = PCI1 + PCI4 + mobo ethernet
The manual for the mobo mentioned that the AGP slot uses the same
IRQ as PCI2 and PCI6, but the IRQ used by the on-board ethernet
port wasn't mentioned *anywhere*. I only found out about it when I
bought a PCI IDE adaptor card and installed it in slot 4. I had no
problems until I started doing MythTV playbacks to a remote
frontend. When I did that, the ethernet port and IDE adaptor both
started hammering the same IRQ line. Eventually the system would
get confused (the kernel watchdog would report an eth0 timeout and
then the IDE driver would report that the drive had failed) and
although the system didn't actually crash, it fell into an
error/retry/error loop that prevented it from doing anything else.
Once I moved the IDE adaptor to a different slot the problem went
away.
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