>> Traced it back to the introduction of NO_HZ. Going from >> CONFIG_HZ_PERIODIC to CONFIG_NO_HZ_IDLE or CONFIG_NO_HZ_FULL is enough >> to do it. > Is this specific to running in a VM or do those options break your host > system as well? Just the guest. The same kernel boots on the host. > >> Earlier in boot there was a message that might be related: >> drivers/rtc/hctosys.c: unable to open rtc device (rtc0) >> And indeed there is not rtc or rtc0 in /dev in the guest like there is >> on the host. I'm guessing this is more missing functionality than it is >> a bug. >> > Hmmm, as far as I understand this, the RTC is not related to having > CONFIG_NO_HZ_FULL and friends. The RTC is only there to provide you an > actual read of wall-clock date/time, where the architected timers should > be used in an ARM VM as the clocsource and to program timer interrupts. > > Tangentially, recent versions of QEMU should have an RTC in the '-M > virt' machine, specifically a pl031, so you could try to add > CONFIG_RTC_DRV_PL031=y to your guest kernel config and see if the > warning above disappears, assuming you have a recent enough version of > qemu (use 2.1.0, or check hw/arm/virt.c for VIRT_RTC in the memmap). Thanks, will try that. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
