From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752913AbeD3JyQ (ORCPT ); Mon, 30 Apr 2018 05:54:16 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:57142 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751027AbeD3JyP (ORCPT ); Mon, 30 Apr 2018 05:54:15 -0400 Date: Mon, 30 Apr 2018 10:54:08 +0100 From: Lorenzo Pieralisi To: Rohit Khanna Cc: Catalin Marinas , "will.deacon@arm.com" , "linux-kernel@vger.kernel.org" , Thierry Reding , Alexander Van Brunt , Bo Yan , Jason Sequeira , Mark Rutland , Vignesh Radhakrishnan , Krishna Sitaraman Subject: Re: [PATCH] arm64: skip cpu nodes marked as disabled in DT Message-ID: <20180430095408.GA32033@e107981-ln.cambridge.arm.com> References: <1524697712-20208-1-git-send-email-rokhanna@nvidia.com> <1524699380207.85374@nvidia.com> <20180426072514.GA33476@MBP.local> <20180426101802.GA1646@e107981-ln.cambridge.arm.com> <1524772461183.61914@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1524772461183.61914@nvidia.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 26, 2018 at 07:54:06PM +0000, Rohit Khanna wrote: > Thanks Lorenzo for pulling out the old thread. > > So just to make sure my understanding is correct from the discussion > on that thread, below is not a preferred approach. > > "If CPUs are marked as disabled in the devicetree, make sure they do > not exist in the system CPU information and CPU topology information." > > > The reason is because - "The meaning of disabled for cpus in ePAPR is > that the cpu is offline (i.e. in a spinloop or wfi), not that the cpu > is unavailable." > > > Preferred approach is - > "Since with this approach the DT should change anyway if on different > > hardware devices based on the same chip you want to allow booting a > > different number of CPUs, why do not we remove the cpu nodes instead of > > disabling them" Yes, I think that's the best course of action and it was the outcome of that email thread. Lorenzo > Thanks > Rohit > ________________________________________ > From: Lorenzo Pieralisi > Sent: Thursday, April 26, 2018 3:18 AM > To: Catalin Marinas; Rohit Khanna > Cc: will.deacon@arm.com; linux-kernel@vger.kernel.org; Thierry Reding; Alexander Van Brunt; Bo Yan; Jason Sequeira; Mark Rutland > Subject: Re: [PATCH] arm64: skip cpu nodes marked as disabled in DT > > On Thu, Apr 26, 2018 at 08:25:14AM +0100, Catalin Marinas wrote: > > On Wed, Apr 25, 2018 at 11:36:06PM +0000, Rohit Khanna wrote: > > > Adding few other folks. > > > > It looks fine to me but cc'ing Mark and Lorenzo (and it should have been > > posted on linux-arm-kernel@lists.infradead.org). > > > > > From: Rohit Khanna > > > Sent: Wednesday, April 25, 2018 4:08 PM > > > To: catalin.marinas@arm.com; will.deacon@arm.com > > > Cc: linux-kernel@vger.kernel.org; Rohit Khanna > > > Subject: [PATCH] arm64: skip cpu nodes marked as disabled in DT > > > > > > Skip the CPU nodes that are marked as disabled in DT. > > > > > > Bug 1828570 > > That's not information that can be used in its current form, which > bug-tracking system ? > > > > Signed-off-by: Rohit Khanna > > > Reviewed-on: http://git-master/r/1245333 > > If it is a public mailing list discussion the > > Link: > > tag and the lkml redirector should be used, I do not know what the > redirector used here is though. > > Process is defined here: > > https://www.kernel.org/doc/html/latest/process/submitting-patches.html > > > > Reviewed-by: Alexander Van Brunt > > > --- > > > arch/arm64/kernel/smp.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > > > index f3e2e3aec0b0..2b4371b0948d 100644 > > > --- a/arch/arm64/kernel/smp.c > > > +++ b/arch/arm64/kernel/smp.c > > > @@ -578,6 +578,10 @@ static void __init of_parse_and_init_cpus(void) > > > for_each_node_by_type(dn, "cpu") { > > > u64 hwid = of_get_cpu_mpidr(dn); > > > > > > + /* Check to see if the cpu is disabled */ > > > + if (!of_device_is_available(dn)) > > > + goto next; > > > + > > This was discussed a long time ago and kind of dropped - I digged the > thread out of archives for everyone's information: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2013-June/174324.html > > Lorenzo