Am 25.10.2010 23:21, Philippe Gerum wrote: > On Mon, 2010-10-25 at 21:40 +0200, Jan Kiszka wrote: >> Am 25.10.2010 21:03, Peter Pastor wrote: >>> Hey Jan, >>> >>> I did not apply any ubuntu patch for kernel 2.6.35 (since I do not have >>> one). Also, good to know that I should not use xenomai patches together >>> with ubuntu patches. >>> >>> Anyway, the problem occurred as well with the kernel 2.6.35 (see attached >>> dmesg_bad_2.6.35) >>> I also attached the config. >>> >> >> ... >> >>> [ 5751.714643] irq 16: nobody cared (try booting with the "irqpoll" option) >>> [ 5751.714649] Pid: 0, comm: swapper Tainted: P >>> 2.6.35-ipipe-2.5.4-slim #2 >>> [ 5751.714653] Call Trace: >>> [ 5751.714655] <IRQ> [<ffffffff8108bb56>] __report_bad_irq+0x26/0xa0 >>> [ 5751.714668] [<ffffffff8108bd5c>] note_interrupt+0x18c/0x1d0 >>> [ 5751.714672] [<ffffffff8108c77d>] handle_fasteoi_irq+0xcd/0x100 >>> [ 5751.714677] [<ffffffff8100656d>] handle_irq+0x1d/0x30 >>> [ 5751.714681] [<ffffffff81005a40>] do_IRQ+0x70/0x100 >>> [ 5751.714685] [<ffffffff81092147>] __ipipe_sync_stage+0x207/0x20d >>> [ 5751.714689] [<ffffffff810059d0>] ? do_IRQ+0x0/0x100 >>> [ 5751.714692] [<ffffffff8109214d>] ? __xirq_end+0x0/0x9c >>> [ 5751.714696] [<ffffffff810059d0>] ? do_IRQ+0x0/0x100 >>> [ 5751.714700] [<ffffffff810926a3>] __ipipe_walk_pipeline+0x113/0x120 >>> [ 5751.714706] [<ffffffff81024414>] __ipipe_handle_irq+0x124/0x310 >>> [ 5751.714708] [<ffffffff8108bf10>] ? __ipipe_ack_fasteoi_irq+0x0/0x10 >>> [ 5751.714712] [<ffffffff814f78d3>] common_interrupt+0x13/0x2c >>> [ 5751.714713] <EOI> [<ffffffff810249d6>] ? __ipipe_halt_root+0x26/0x40 >>> [ 5751.714718] [<ffffffff81061191>] ? atomic_notifier_call_chain+0x11/0x20 >>> [ 5751.714722] [<ffffffff8100cbd5>] default_idle+0x45/0x50 >>> [ 5751.714725] [<ffffffff8100198a>] cpu_idle+0x7a/0xd0 >>> [ 5751.714728] [<ffffffff814f14a1>] start_secondary+0x1c1/0x1c5 >>> [ 5751.714730] handlers: >>> [ 5751.714730] [<ffffffff8136ed60>] (usb_hcd_irq+0x0/0xb0) >>> [ 5751.714735] [<ffffffffa00bac30>] (mpt_interrupt+0x0/0xa00 [mptbase]) >>> [ 5751.714747] Disabling IRQ #16 >> >> I'm not yet sure, but a first thought: We have a shared fasteoi IRQ >> here, and we are on SMP. Compared to vanilla, the fasteoi flow of ipipe >> looks so much different to me ATM that I tend to believe two cores end >> up having this IRQ queued at the same time. One runs first and handles >> all triggers, the second bails out like above. >> >> Philippe, we _end_ fasteoi in the ipipe ack path. Do we mask them prior >> to this? What prevents a second IRQ arriving after this early eoi? > > All fasteoi handlers are supposed to mask+ack when the pipeline is > enabled,
What am I missing? The code I was looking at (__ipipe_ack_fasteoi) just does a regular eoi at chip level. > to avoid interrupt storm due to the deferral we may introduce > in the irq delivery. I do see this in the regular ioapic chip > descriptor, but this is lacking with interrupt remap. I guess we could > have a problem with Intel IOMMUs. IOMMUs should blow up the system anyway once a PCI driver is used in the RT domain (DMA remapping involved Linux locks and may even allocate memory). Guess we should add a !IPIPE to their Kconfig entries. Jan
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