From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: please revert c/s 17686 Date: Thu, 12 Jun 2008 14:28:49 +0100 Message-ID: <485140B1.76E4.0078.0@novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com Cc: Gang Wei , ke.yu@intel.com List-Id: xen-devel@lists.xenproject.org Switching HPET into legacy mode is not acceptable, as this doesn't only cut off the PIT channel 0 interrupt, but also the RTC one. The former is acceptable as no domain will ever gain control over it, but the latter = isn't as Dom0 may validly make use of it. I'm observing a failure of setting the system clock correctly due to this issue (hwclock checks whether the RTC update interrupt is occurring as expected), and I suppose other uses of /dev/rtc would also suffer. It is my understanding that using the HPET to overcome the APIC timer stop issue is therefore impossible at present - you cannot use legacy mode, and you also cannot use the individual routing mode as whatever IRQ is chosen may turn out being in use by one or more other devices (and hence would require sharing the IRQ between Xen and one or more guests). Thanks, Jan