Re: [PATCH v4 35/35] OvmfPkg/OvmfXen: use RealTimeClockRuntimeDxe from EmbeddedPkg


Anthony PERARD
 

On Wed, Aug 07, 2019 at 06:09:57PM +0200, Roger Pau Monné wrote:
On Mon, Jul 29, 2019 at 04:39:44PM +0100, Anthony PERARD wrote:
A Xen PVH guest doesn't have a RTC that OVMF would expect, so
PcatRealTimeClockRuntimeDxe fails to initialize and prevent the
firmware from finish to boot. To prevent that, we will use
XenRealTimeClockLib which simply always return the same time.
This will work on both Xen PVH and HVM guests.
Not that this is not correct, but what's the point in requiring a
clock if it can be faked by always returning the same value?
It's not a clock that is required, it is a library that implements
RealTimeClockLib. Something needs it, so it is provided, even if it is
only to display the "current time".

It seems like it's usage is not really required, and could indeed be
dropped altogether?
Way to much work to drop it. Also, I don't work to fork OVMF.

The ARM implementation of OVMF for Xen does the same thing and simply
always return the same value.

Alternatively, there's the PV clock which is available to PVH guests
and will return a proper time.
We might need to do that one day I guess, but right now it is just a
nice to have.

Thanks,

--
Anthony PERARD

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