From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lorenzo Pieralisi Subject: Re: [PATCH v9 18/21] ARM64 / ACPI: Select ACPI_REDUCED_HARDWARE_ONLY if ACPI is enabled on ARM64 Date: Tue, 10 Mar 2015 14:16:46 +0000 Message-ID: <20150310141645.GA25123@red-moon> References: <1424853601-6675-1-git-send-email-hanjun.guo@linaro.org> <1424853601-6675-19-git-send-email-hanjun.guo@linaro.org> <20150306174715.GA26888@e102568-lin.cambridge.arm.com> <54FEE227.4000808@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from foss.arm.com ([217.140.101.70]:42981 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752011AbbCJOQz (ORCPT ); Tue, 10 Mar 2015 10:16:55 -0400 Content-Disposition: inline In-Reply-To: <54FEE227.4000808@linaro.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Hanjun Guo Cc: Catalin Marinas , "Rafael J. Wysocki" , Will Deacon , Olof Johansson , "grant.likely@linaro.org" , Arnd Bergmann , Mark Rutland , "graeme.gregory@linaro.org" , Sudeep Holla , "jcm@redhat.com" , Marc Zyngier , Mark Brown , Robert Richter , Timur Tabi , Ashwin Chaugule , "suravee.suthikulpanit@amd.com" , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , linaro-acpi@lists.linaro. On Tue, Mar 10, 2015 at 12:23:03PM +0000, Hanjun Guo wrote: > On 2015=E5=B9=B403=E6=9C=8807=E6=97=A5 01:47, Lorenzo Pieralisi wrote= : > > On Wed, Feb 25, 2015 at 08:39:58AM +0000, Hanjun Guo wrote: > >> From: Al Stone > >> > >> ACPI reduced hardware mode is disabled by default, but ARM64 > >> can only run properly in ACPI hardware reduced mode, so select > >> ACPI_REDUCED_HARDWARE_ONLY if ACPI is enabled on ARM64. > > > > Agreed. This will remove unneeded acpica code. I think though, > > you should also check the FADT flag HW_REDUCED_ACPI at boot to > > make sure that the tables are HW reduced compliant. I am flagging >=20 > Agreed, I will add that check on top of this patch set. We explicitly > stated that we are using hardware reduced mode on ARM64 in the doc, s= o,=20 > how about print some warning message and go on with the boot if we > got the wrong flag HW_REDUCED_ACPI at boot? Why would be boot if the ACPI tables are not HW_REDUCED_ACPI compliant = ? To look for trouble :) ? arm64 does not support any other ACPI model, the missing flag should disable ACPI IMO on arm64. You could add a check in this patch same place where you check the FADT version and be done with this. Thank you ! Lorenzo > > this up because I noticed code in core code (not guarded by > > ifdef) that checks: > > > > acpi_gbl_reduced_hardware > > > > and if it is not set it goes on instantiating fixed HW devices. > > > > drivers/acpi/scan.c:2567 > > > > It is just a heads up, I think it is harmless, but one thing is > > removing acpica code on ACPI HW reduced only, the other is to make > > sure the kernel does not try to use ACPI HW features that acpica > > can't support. >=20 > I agree, need some cleanups for the ACPICA code I think, and this > was raised about 1 and half years ago and Intel folks need more > consideration on that [1]. >=20 > [1]: http://comments.gmane.org/gmane.linux.acpi.devel/63844 >=20 > Thanks > Hanjun >=20 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html