I think this is related to kvm module in 4.4's in-kernel irq chip. If one runs with kernel_irqchip=off property set on the qemu command, then even Xenial on Xenial SMP never fails.
Installing the 16.04 HWE Edge kernel (4.8.0-30) on my Xenial host resolves this as well. On Wed, Dec 14, 2016 at 8:17 PM, Ryan Harper <[email protected]> wrote: > The other oddity, running the guest with 1 cpu always works for me in the > cases where it failed before. > > > On Wed, Dec 14, 2016 at 5:37 PM, Ryan Harper <[email protected]> > wrote: > >> >> >> On Wed, Dec 14, 2016 at 4:31 PM, Seth Forshee < >> [email protected]> wrote: >> >>> Looking at kernel 4.9, the RTC_UIE_ON ioctl sets an alarm via the >>> cmos_rtc driver. This does a couple of things. >>> >>> 1. Disables the CMOS RTC alarm interrupt, writes an alarm time to the >>> CMOS RTC, then enables the alarm interrupt. >>> >>> 2. When configured to emulate an RTC using the HPET (which our kernel >>> is), makes sure HPET timer 1 is initialized for RTC emulation. >>> >>> Based on this I looked at the diffs for hw/timer/mc146818rtc.c (which >>> seems to be the CMOS RTC device) and hw/timer/hpet.c between the two >>> qemu versions. The differences all look pretty trivial, I don't see >>> anything which looks like it would have fixed the problem. >>> >> >> It's a guest kernel + qemu interaction. In the past, there was an issue >> w.r.t >> ensuring RTC interrupts were being delivered; that's what's currently >> broken. >> >> Comparing: grep rtc /proc/interrupts where it works (Trusty) vs failed, >> and you can see >> that we get at most a few interrupts to the RTC device. >> >> There isn't a whole lot of change to qemu's RTC between 2.5 and 2.6.1 in >> yakkety >> So, I need to see if running yakkety qemu on Xenial fixes things as well >> so we can >> continue to narrow down where the regression was introduced. >> >> >>> >>> -- >>> You received this bug notification because you are subscribed to qemu in >>> Ubuntu. >>> https://bugs.launchpad.net/bugs/1649718 >>> >>> Title: >>> Linux rtc self test fails in a VM under xenial >>> >>> To manage notifications about this bug go to: >>> https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1649718/ >>> +subscriptions >>> >> >> > -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1649718 Title: Linux rtc self test fails in a VM under xenial To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1649718/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
