Alex Williamson wrote: > On Thu, 2014-10-23 at 19:33 +0200, Andreas Hartmann wrote: >> Alex Williamson wrote: >> [...] >>> If you use Bjorn's previous patch to disable VC save/restore and my >>> patch to reorder the reset mechanisms, does echo 1 > reset for the sysfs >>> entry for the device also still cause a hang? >> >> Yes - it's hanging too (w/ vfio bound to the device - didn't test other >> possibilities). > > Does it happen regardless of the slot the card is plugged into? Thanks, As I already wrote, it's not possible to plug the device to another port. But besides that, let me stress some "findings" I made over the past view weeks I'm now knowing about this problem. Maybe it gives you an idea about what's going on: - I did all of the tests in text mode on the console. Normally, there is a blinking cursor. When doing the echo 1 > reset, the shell doesn't come back again and the blinking of the cursor gets immediately slower. Getting slower means: it takes some more time until it is on / off again again. This way, it "blinks" another not exceeding 2 times until it's finally dead. It looks like the machine would have suddenly extremely high load (there are 8 cores!) - but this seems to be not true, because the cpu fan stays silent - the rpm isn't changed at all. - Most of the time, I'm doing tests which fail, I'm having problems after the hang with USB (it's the Etron device). Problem means: initrd isn't able to communicate with the device (but bios and grub2 didn't had any problem, because keyboard worked fine, which is connected via USB 3). At this point, it is necessary to disconnect the mains completely and wait half a minute until the problem disappears. Seldom, I too had this problem even on bios stage: the keyboard couldn't be seen even by the bios any more. - Sometimes (really seldom - now happened about 3 times), it gets extremely hard to return to normal operation after that hang. This means: Since a few weeks, I'm running kernel 3.12.28-3-desktop out of the box (= as provided by openSUSE). Sometimes now, I got (apparently) the same problems (= PCIe passthrough hangs the complete machine) w/ 3.12.28 as I'm having with stock >= 3.14 after testing. It's even useless then to reconnect the mains (I experienced this 2 times in series after one hang yesterday). At this point, I have to run kernel 3.10.x (which runs pretty fine as usual) and only after that, 3.12 works again as expected (as appeared once yesterday while tests w/ disabled USB 3 devices via bios). - I think there is a relationship between how long the hang is active and the consecutive problems coming up. If the hang is immediately (max about 1s) reset w/ the reset knob, it is possible, that there is no USB problem after reboot and the machine works completely fine with 3.12.x again. Conclusion (from my point of view): The broken reset seems to do something really _extreme ugly_ w/ the hardware, which has the potential to break the hardware "lasting" or the consecutive software isn't able at all to correctly reconfigure the system again - even after reconnecting the mains. Fortunately I'm having an old kernel version (3.10.x), which seems to be able to "repair" the hardware again. But I have to emphasis that the situation is really highly questionable and I'm meanwhile fearing to break my board finally, which is working really _extremely_ stable besides that. Out of interest: Bjorn's patch disables vc save/restore support - and the machine works fine again. Why is it needed at all if it seems to work perfectly w/o it? What's the additional benefit? Or in other words: What am I missing until today :-) ? What would be better? What could I do more? Thanks, kind regards, Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
