From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH 3/5] RTC: Add UIP(update in progress) check
 logic
Date: Mon, 5 Mar 2012 10:36:20 -0800
Message-ID: <1330972580.22559.33.camel@cthulhu.hellion.org.uk>
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To: "Zhang, Yang Z" <yang.z.zhang@intel.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Jan Beulich <JBeulich@suse.com>
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On Mon, 2012-03-05 at 03:25 -0500, Zhang, Yang Z wrote:
> The UIP(update in progress) is set when RTC is in updating. And the
> update cycle begins 244us later after UIP is set. 

Not arguing against this patch but OOI how important is it to emulate
this behaviour to this level of accuracy? On real hardware the UIP tells
you that the data may not be valid/consistent but I don't think the
emulated RTC has that property (does it?). Do guest OSes rely on seeing
the UIP bit occasionally or have you seen a specific issue which caused
you to make this change?

Ian.