Description of problem:
PL031 is a real time clock.
Although it is not found on real hardware AFAICT, it is emulated by
qemu-system-aarch64 and therefore it's a useful way to get wallclock
time in VMs.
There is no kvmclock on !x86, and without PL031 the VM's time will
be set to 1/1/1970 for a long time (until you start ntpd which is quite
a long time into the boot process, and never happens in libguestfs VMs).
I have enabled this option in my kernel and tested it booting on
both the real hardware and inside a VM. It has no effect on the
In the VM it ensures that the wallclock is set correctly close to boot.
You will see this message during VM boot:
[ 0.742380] rtc-pl031 90010000.pl031: rtc core: registered pl031 as rtc0
[ 0.789316] rtc-pl031 90010000.pl031: setting system clock to 2014-07-28 14:21:39 UTC (1406557299)
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Start a KVM VM.
2. Observe the clock in the VM. It is set to 1/1/1970.
CONFIG =y or =m ?
(In reply to Don Dutile from comment #1)
> CONFIG =y or =m ?
I'm testing it compiled in (=y). It doesn't affect boot on the
aarch64 real hardware. I believe it'd be better for the clock to
be compiled in so that it can be initialized as soon as possible.
I've been testing this patch for months. What can I do to
get this actioned? I will push it myself if permitted.
diff --git a/config-arm64 b/config-arm64
index bdcc9b9..eac2b9a 100644
@@ -52,7 +52,7 @@ CONFIG_NFS_USE_KERNEL_DNS=y
# CONFIG_PL330_DMA is not set
# CONFIG_RTC_DRV_PL030 is not set
-# CONFIG_RTC_DRV_PL031 is not set
# CONFIG_SERIAL_AMBA_PL010 is not set
I'll change it in today's rawhide build.