MrMorden Posted April 14, 2005 Report Share Posted April 14, 2005 Hey everyone: My sound suddenly stopped working, for no apparent reason. So I went back to /proc/interrupts and found that Linux had, for some reason, assigned the same interrupt to both eth0 and Nvidia NForce2. This means, of course, that the sound will only work if I'm not connected to the 'net. I managed to solve this problem before by mucking around in the BIOS, but I'm not sure exactly what I did. (That is, I wasn't sure what I was doing the first time; not that I solved it with full knowledge and forgot.) So I spent another hour changing around the PnP/IRQ settings, and the few times I managed to "trick" Linux into putting eth0 and Nvidia NForce2 on separate interrupts, the sound still refused to work. I suspect that this has something to do with the fact that the interrupt with NForce2 was listed as XT-PIC instead of IO-APIC-edge like everything else. I suspect this because I can get the sound working properly if I disconnect eth0, and in this case the interrupt with Nvidia Nforce2 is listed as IO-APIC-edge. System information is as follows: Motherboard: Gigabyte GA-7NNXP (NForce2) Processor: Athlon XP 3200+ kernel: 2.6.8.1-12mdkcustom Version: Mandrake 10.1 Official Thank you! -MrMorden Quote Link to comment Share on other sites More sharing options...
MrMorden Posted April 14, 2005 Author Report Share Posted April 14, 2005 (edited) How's this for irony? Immediately after I post, I decide "I'll try ONE MORE THING," which was setting IRQ 9 to "reserved," where Nvidia Nforce 2 would show up as XT-PIC. Now it's showing up on IRQ 4 as IO-APIC-edge, and it's working. As grateful as I am that it's no longer broken, I find it frustrating that I don't know why it's fixed or why it broke again in the first place. Anyone have any thoughts? Thanks, -MrMorden Edit: Finished a sentence Edited April 14, 2005 by MrMorden Quote Link to comment Share on other sites More sharing options...
adamw Posted April 14, 2005 Report Share Posted April 14, 2005 probably APIC screwing up again. APIC is great when it works. It's a bit hard to test now you _fixed_ it of course, but booting Linux with 'noapic' as a boot parameter may well also have fixed the problem. Quote Link to comment Share on other sites More sharing options...
MrMorden Posted April 14, 2005 Author Report Share Posted April 14, 2005 From what I gather, APIC is supposed to (har, har) allow multiple pieces of hardware to access the same interrupt, right? So why does it work flawlessly in Windows but not in Linux? What effect would setting apic=off or lapic=off in lilo have on my computer, besides possibly fixing the problem? Quote Link to comment Share on other sites More sharing options...
adamw Posted April 14, 2005 Report Share Posted April 14, 2005 I thought it basically dynamically allocates interrupts on demand, but I'm willing to be wrong...I'll check it out later. Regardless, the answer to your question in most cases is 'not a sausage'. You need local APIC for multiprocessor setups, and if you have a ton of hardware I guess you might run out of IRQs (like we all used to back when soundcards needed to run on something under 10 and they were all full...). Otherwise, nada. If something went wrong it'd be fairly immediately obvious, as well (i.e. bits of hardware would stop working), I think. Quote Link to comment Share on other sites More sharing options...
MrMorden Posted April 14, 2005 Author Report Share Posted April 14, 2005 Nope, single processor setup here, and I've got about 10 devices that call for an interrupt and 15 interrupts all told. As for APIC's supposed functionality (har, har) you seem more knolwedgable than I am, and my understanding came from a brief glance at linuxquestion's Linux Wiki, so you're probably right. In any case, thanks for the possible solution, when it happens next time, I'll try turning off APIC in lilo. Regards, MrMorden Quote Link to comment Share on other sites More sharing options...
AussieJohn Posted April 15, 2005 Report Share Posted April 15, 2005 Do you have Plug & Play , disabled in the bios.??? I have always followed this recommendation. I also select noapic nolapic and also apic=off. I have never had to fiddle with interrupts in 3.5 yrs. I also use lan and have a nvidia video card. I should also mention that my computer is a PC and not a laptop so I don't know that side of things. John. Quote Link to comment Share on other sites More sharing options...
MrMorden Posted April 15, 2005 Author Report Share Posted April 15, 2005 Do you have Plug & Play , disabled in the bios.??? <{POST_SNAPBACK}> I've been poking around the BIOS, and I can't find an option that says something along the lines of Plug and Play: Enable/disable. The closest thing I could find was a section called "PnP/PCI Configuration" which has an "Auto/manual" assignment option for PCI devices. Of course, setting this option to manual did not fix the problem. As for the desktop/laptop thing, my computer is a desktop, not a laptop. Quote Link to comment Share on other sites More sharing options...
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