From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jennifer Herbert Subject: Legacy PIC (x86) support (RTC) in dom0 with Linux 4.12 and newer is broken for some hardware. Date: Tue, 4 Dec 2018 17:24:08 +0000 Message-ID: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4479491446057027705==" Return-path: Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1gUEnS-0004AK-7V for xen-devel@lists.xenproject.org; Tue, 04 Dec 2018 17:47:46 +0000 Content-Language: en-US List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" To: "'xen-devel@lists.xenproject.org'" List-Id: xen-devel@lists.xenproject.org --===============4479491446057027705== Content-Language: en-US Content-Type: multipart/alternative; boundary="_000_a46c25e311ed4a42a201583709920ab0AMSPEX02CL03citritenet_" --_000_a46c25e311ed4a42a201583709920ab0AMSPEX02CL03citritenet_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Since Linux 4.12, there has been a commit a1e23a42f1bdc00e32fc4869caef12e4e= 6272f26 "rtc: cmos: Do not assume irq 8 for rtc when there are no legacy irqs" The commit effectively disabled requesting IRQ 8 for systems without PIC controller present (As in the case when used at dom0 under Xen) and at the same time where this IRQ is not explicitly described in ACPI tables. I have found hardware without this IRQ in the ACPI tables, and indeed, found the RTC to be broken in dom 0. Temporarily, I reverted this commit, which fixed the problem, but I was wondering if anyone here knew of a better solution? Cheers, -jenny --_000_a46c25e311ed4a42a201583709920ab0AMSPEX02CL03citritenet_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable 
Since Linux 4.12, there has been a commit a1e23a42f1bdc00e32fc4869caef12e4e6272f26=

“rtc: cmos: =
Do not assume irq 8 for rtc when there are no legacy irqs”=

 <=
/span>
The commit effecti=
vely disabled requesting IRQ 8 for systems without PIC

controller present=
 (As in the case when used at dom0 under Xen) and at

the same time wher=
e this IRQ is not explicitly described in ACPI tables.

 <=
/span>


I have found hardw=
are without this IRQ in the ACPI tables, and indeed,

found the RTC to b=
e broken in dom 0.  Temporarily, I reverted this

commit, which fixe=
d the problem, but I was wondering if anyone here


knew of a better s=
olution?


 


Cheers,


 


-jenny


 
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