From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: Arndale secondary CPU boot issue Was Re:
 [xen-unstable test] 60076: regressions - FAIL
Date: Thu, 30 Jul 2015 11:38:18 +0100
Message-ID: <55B9FE9A.8060903@citrix.com>
References: <osstest-60076-mainreport@xen.org>
	<1438160718.16912.16.camel@citrix.com> <55B8DEBC.7010807@citrix.com>
	<55B8E011.6070609@citrix.com> <55B918F7.6080302@citrix.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
In-Reply-To: <55B918F7.6080302@citrix.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Julien Grall <julien.grall@citrix.com>, Dario Faggioli <dario.faggioli@citrix.com>, osstest service owner <osstest-admin@xenproject.org>
Cc: David Vrabel <david.vrabel@citrix.com>, xen-devel@lists.xensource.com, Ian Campbell <Ian.Campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
List-Id: xen-devel@lists.xenproject.org

On 29/07/15 19:18, Julien Grall wrote:
> On 29/07/15 15:15, Julien Grall wrote:
>>>> Can it be that things are "just" slow, since we're creating a 4 vcpus
>>>> guest on a 1 pcpu (not so powerful, I guess) host?
>>> The arndale board has a 2 physical CPUs. Although it looks like that the
>>> secondary cpu is never coming up:
>>>
>>> Jul 28 01:35:39.057076 (XEN) Adding cpu 1 to runqueue 0
>>> Jul 28 01:35:39.057104 (XEN) Bringing up CPU1
>>> Jul 28 01:35:39.064998 (XEN) CPU1 never came online
>>> Jul 28 01:35:40.065133 (XEN) Removing cpu 1 from runqueue 0
>>> Jul 28 01:35:40.065176 (XEN) Failed to bring up CPU 1 (error -5)
>>>
>>> This has been broken at some point in Xen 4.6. Xen 4.5 is booting with
>>> the right number of physical on the Arndale.
> I figured out what's going on. The problem interestingly came after the
> commit which added the support of the ticket lock [1] in Xen.
>
> While the problem is solved by reverting this patch, the source of the
> issue is not because of a ticket lock issue with ARM (thanks god!).

As an aside, why is failing to bring up a cpu not fatal under ARM?

I admit that x86 isn't much better in this regard - it will spin in an
infinite loop waiting for the upcoming cpu to call in, but it least it
doesn't proceed booting with some cpus unexpectedly missing.

~Andrew