From: Yi, Shunli
Sent: Friday, October 08, 2010 3:59 AM
To: Xen Devel
Subject: [Xen-devel] Allow the backward time syncing in domU.
When we use dependent clock in domU, the time syncing from
Dom0 to DomU is monotonic (in xenified kernel 22.214.171.124 ).
While, when I read the source code of arch/i386/time-xen.c,
I think we can allow the backward time syncing by reset the monotonic time
value (monotonic.tv) when the HYPERVISOR_shared_info->wc_version is changed.
I’ve tested that, whenever the Dom0 time changed, the
domU’s time would be sync-ed immediately. (with
So, seems it works perfect, it’s a real dependent wall
It’s easy to implement the backward time syncing.
So, I wonder that, are there some risks to allow the
backward time syncing?
If there isn’t known risk, I’d like to send a
patch to allow the backward time syncing.
Could you anybody can help to understand the risks?
Any input is appreciated.
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