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* [PATCH net-next] ptp: Remove 'default y' for VMCLOCK PTP device
@ 2024-11-02 21:52 David Woodhouse
  0 siblings, 0 replies; only message in thread
From: David Woodhouse @ 2024-11-02 21:52 UTC (permalink / raw)
  To: Jakub Kicinski
  Cc: Richard Cochran, Peter Hilber, linux-kernel, virtualization,
	linux-arm-kernel, linux-rtc, Ridoux, Julien, virtio-dev,
	Luu, Ryan, Chashper, David, Mohamed Abuelfotoh, Hazem,
	Paolo Abeni, Christopher S . Hall, Jason Wang, John Stultz,
	Michael S . Tsirkin, netdev, Stephen Boyd, Thomas Gleixner,
	Xuan Zhuo, Marc Zyngier, Mark Rutland, Daniel Lezcano,
	Alessandro Zummo, Alexandre Belloni, qemu-devel, Simon Horman

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From: David Woodhouse <dwmw@amazon.co.uk>

The VMCLOCK device gives support for accurate timekeeping even across 
live migration, unlike the KVM PTP clock. To help ensure that users can
always use ptp_vmclock where it's available in preference to ptp_kvm,
set it to 'default PTP_1588_CLOCK_VMCLOCK' instead of 'default y'.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 drivers/ptp/Kconfig | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
index e98c9767e0ef..ed087ae75f0e 100644
--- a/drivers/ptp/Kconfig
+++ b/drivers/ptp/Kconfig
@@ -135,12 +135,16 @@ config PTP_1588_CLOCK_VMCLOCK
 	tristate "Virtual machine PTP clock"
 	depends on X86_TSC || ARM_ARCH_TIMER
 	depends on PTP_1588_CLOCK && ACPI && ARCH_SUPPORTS_INT128
-	default y
+	default PTP_1588_CLOCK_KVM
 	help
 	  This driver adds support for using a virtual precision clock
 	  advertised by the hypervisor. This clock is only useful in virtual
 	  machines where such a device is present.
 
+	  Unlike the KVM virtual PTP clock, the VMCLOCK device offers support
+	  for reliable timekeeping even across live migration. So this driver
+	  is enabled by default whenever the KVM PTP clock is.
+
 	  To compile this driver as a module, choose M here: the module
 	  will be called ptp_vmclock.
 
-- 
2.44.0



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2024-11-02 21:52 [PATCH net-next] ptp: Remove 'default y' for VMCLOCK PTP device David Woodhouse

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