[linux-dvb] Re: Fwd: Re: DEBI irq oops, crashes: kernel 2.6 & Hyperthreading unusable with DVB

[Johannes Stezenbach <js@convergence.de>]

Udo Wolter wrote:
> 
> I read about an nmi-watchdog in the documentation of the kernel.
> Maybe I can find more information regarding the hard lockup of the
> machine when I switch this feature on. I've never done this before
> (virtually I never planned to go that deep in the linux kernel *sigh*)
> so please be patient until I can give you more informations.

If you get an oops message from the nmi-watchdog, please post it here.
The nmi-watchdog will not catch all lockups, though. If e.g.
a DMA transfer goes to the wrong address (due to a race condition),
and overwrites essential data/code (like exception handlers...)
the NMI won't help.

> PS: What does DEBI and GPIO stands for ? What is the purpose of those
>     terms ?

The saa7146 data sheet can be found somewhere on the net.

DEBI = data bus extension interface
GPIO = general purpose I/O

DEBI irq is triggered after a DMA transfer from/to the dual-ported
RAM (DPRAM) on the av7110-card is finished.
The av7110 firmware can also request irqs to the PC via a GPIO line.
It uses some locations in DPRAM (IRQ_STATE etc.) to communicate
the request details.

Johannes


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