Re: [LAD] rtirq script is broken with 2.6.31

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Paul Davis wrote: I don't know all the details of the implementation; NTL I take it that a lower priority IRQ handler can be preempted in favor of one with a higher priority even if they're on the same IRQ line. It won't do any good for level-sensitive IRQs, but with hardirq preemption fasteoi does replay edge interrupts: If an IRQ arrives, rt-linux sends an EOI. If the edge IRQ comes again (while linux is processing the same IRQ), non-threaded handler marks IRQ to be replayed, then masks it and sends EOI. When the thread awakes, it unmasks the IRQ before handle_IRQ_event, so that it can catch the next edge IRQ. Here's what Thomas Gleixner wrote announcing 2.6.31-rc4-rt1: Another interesting detail is that the new forced threaded code uses per device threads instead of per interrupt line threads as we have done in the past. This was just a logical consequence of the per device thread (voluntary threading) infrastructure in mainline and allows us now to share an interrupt line between a hardirq based handler and a threaded handler device. One use case which comes to my mind is AT91 which shares the timer and the serial port interrupt; we now can solve that problem w/o nasty hacks by requesting a threaded handler for the serial port which shuts up the serial device interrupt in the hard interrupt handler part. ..for further details just ask the rt-linux ML or attend the eleventh Real-Time Linux Workshop on September 28 to 30, in Dresden, Germany ;)