Messages in this thread | | | Date | Thu, 19 May 2016 15:39:45 +0300 | From | Nikolai Zhubr <> | Subject | Re: x86_64, Haswell, unhandled vga irqs before i915 loaded |
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Ping? Nobody interested? Maybe there is some more appropriate (specialized) place to ask? Any hints appreciated, Thank you.
Please CC me, I'm not subscribed.
Regards, Nikolai
14.05.2016 11:21, I wrote: > Hello all, > > Some of my motherboards exhibit the [in]famous bug of throwing unwanted > (and unhandled) irqs from integrated intel video core on monitor cable > plug/unplug events when there is no specific chipset driver loaded > (yet). Searching some forums yields this apparently started happening > (sometimes?) starting from Sandy Bridge, affecting both analog VGA > output and digital (DVI, HDMI) outputs. > > Currently, I observe this with 4.1.13 kernel (I could also test some > later one but I suppose nothing relevant has changed since). > Unfortunately the warning message from the kernel in this particular > case is extremally unhelpfull and confusing, because the irq line in > question usually happen to be shared with some usb and/or netcard etc., > so kernel keeps talking about usb and/or netcard, so people end up being > totally confused. > > How to reproduce: > - get some relevant motherboard (Mine is gigabyte ga-b85-hd3 rev 2.1) > - ensure i915.ko (or any fb drivers) not automatically loaded on boot. > - watch dmesg and /proc/interupts > - start plugging/unplugging VGA or HDMI monitor cable. > > What you will see then (approxmately): > > /proc/interupts: > ... > 16: 100001 0 0 IR-IO-APIC-fasteoi ehci_hcd:usb5 > ... > (100000 counter increase in a fraction of second) > > dmesg: > irq 16: nobody cared (try booting with the "irqpoll" option) > ... > Disabling IRQ #16 > > Now meanwhile freebsd people have apparently managed to fix the problem > with a one-liner patch, but I can not test it yet because adapting this > patch for linux is a bit beyond my capability. > This is the discussion: > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=156596 > This is the patch: > https://svnweb.freebsd.org/base?view=revision&revision=284012 > This is the commit log: > Disable VGA PCI interrupts until a chipset driver is loaded for VGA > PCI devices. Else unhandled display adapter interrupts might freeze > the CPU or consume a lot of CPU. > > My understanding is that the problem is caused by buggy BIOS rather than > the kernel, but e.g. in my case no usefull BIOS update is available > (yet?), and still I'd like to "fix" it anyhow. > > *** Please CC me, I'm not subscribed! > > Thank you, > > Regards, > Nikolai
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