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The PL031 RTC tracks the difference between the guest RTC and the host RTC using a tick_offset field. For migration, however, we currently always migrate the offset between the guest and the vm_clock, even if the RTC clock is not the same as the vm_clock; this was an attempt to retain migration backwards compatibility. Unfortunately this results in the RTC behaving oddly across a VM state save and restore -- since the VM clock stands still across save-then-restore, regardless of how much real world time has elapsed, the guest RTC ends up out of sync with the host RTC in the restored VM. Fix this by migrating the raw tick_offset. To retain migration compatibility as far as possible, we have a new property migrate-tick-offset; by default this is 'true' and we will migrate the true tick offset in a new subsection; if the incoming data has no subsection we fall back to the old vm_clock-based offset information, so old->new migration compatibility is preserved. For complete new->old migration compatibility, the property is set to 'false' for 4.0 and earlier machine types (this will only affect 'virt-4.0' and below, as none of the other pl031-using machines are versioned). Reported-by: Russell King <rmk@armlinux.org.uk> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Message-id: 20190709143912.28905-1-peter.maydell@linaro.org |
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| .. | ||
| a9gtimer.h | ||
| allwinner-a10-pit.h | ||
| arm_mptimer.h | ||
| armv7m_systick.h | ||
| aspeed_rtc.h | ||
| aspeed_timer.h | ||
| cmsdk-apb-dualtimer.h | ||
| cmsdk-apb-timer.h | ||
| digic-timer.h | ||
| hpet.h | ||
| i8254_internal.h | ||
| i8254.h | ||
| imx_epit.h | ||
| imx_gpt.h | ||
| m48t59.h | ||
| mc146818rtc_regs.h | ||
| mc146818rtc.h | ||
| mips_gictimer.h | ||
| mss-timer.h | ||
| nrf51_timer.h | ||
| pl031.h | ||
| stm32f2xx_timer.h | ||
| sun4v-rtc.h | ||
| xlnx-zynqmp-rtc.h | ||