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Date: Wed, 2 Dec 2015 14:15:42 +0000
From: David Vrabel <david.vrabel@citrix.com>
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To: Sander Eikelenboom <linux@eikelenboom.it>, <boris.ostrovsky@oracle.com>,
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CC: <linux-kernel@vger.kernel.org>, <xen-devel@lists.xen.org>
Subject: Re: [Xen-devel] linux 4.4 Regression: 100% cpu usage on idle pv guest
 under Xen with single vcpu.
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On 28/11/15 15:47, Sander Eikelenboom wrote:
> 
> -rtc_cmos rtc_cmos: hctosys: unable to read the hardware clock
> +hctosys: unable to open rtc device (rtc0)
> 
> -genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0)
> -hvc_open: request_irq failed with rc -16.

I have reproduced this issue.  We really shouldn't have an RTC device in
a PV guest and I think this irq conflict breaks hvc0.

David