Re: [PATCH RESEND] ptp: add VMware virtual PTP clock driver

[David Miller]

From: Vivek Thampi <vithampi@xxxxxxxxxx>
Date: Fri, 28 Feb 2020 05:32:46 +0000

> Add a PTP clock driver called ptp_vmw, for guests running on VMware ESXi
> hypervisor. The driver attaches to a VMware virtual device called
> "precision clock" that provides a mechanism for querying host system time.
> Similar to existing virtual PTP clock drivers (e.g. ptp_kvm), ptp_vmw
> utilizes the kernel's PTP hardware clock API to implement a clock device
> that can be used as a reference in Chrony for synchronizing guest time with
> host.
> 
> The driver is only applicable to x86 guests running in VMware virtual
> machines with precision clock virtual device present. It uses a VMware
> specific hypercall mechanism to read time from the device.
> 
> Reviewed-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
> Signed-off-by: Vivek Thampi <vithampi@xxxxxxxxxx>
> ---
>  Based on feedback, resending patch to include a broader audience.

If it's just providing a read of an accurate timesource, I think it's kinda
pointless to provide a full PTP driver for it.