From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Stone Subject: Re: [PATCH v5 1/5] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE_ONLY to enforce this ACPI mode Date: Wed, 08 Jan 2014 16:55:58 -0700 Message-ID: <52CDE58E.5000001@redhat.com> References: <1389142011-27356-1-git-send-email-al.stone@linaro.org> <1389142011-27356-2-git-send-email-al.stone@linaro.org> <201401081346.25767.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47855 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932128AbaAHX4a (ORCPT ); Wed, 8 Jan 2014 18:56:30 -0500 In-Reply-To: <201401081346.25767.arnd@arndb.de> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Arnd Bergmann , linux-arm-kernel@lists.infradead.org Cc: al.stone@linaro.org, linux-acpi@vger.kernel.org, Hanjun Guo , patches@linaro.org, linaro-kernel@lists.linaro.org, linaro-acpi@lists.linaro.org On 01/08/2014 05:46 AM, Arnd Bergmann wrote: > On Wednesday 08 January 2014, al.stone@linaro.org wrote: >> Even though support for X86 in hardware reduced mode is possible, it >> is NOT enabled. Extensive effort has gone into the Linux kernel so that >> there is a single kernel image than can run on all x86 hardware; the kernel >> changes run-time behavior to adapt to the hardware being used. This is not >> currently possible with the existing ACPICA infrastructure but only presents >> a problem on achitectures supporting both hardware-reduced and legacy modes >> of ACPI -- i.e., on x86 only. > > Not sure about the logic here: While it's certainly possible to build a kernel > that runs on all x86 machines, it's also possible to build one that only > runs on some of them when some basic options are turned off. I don't see > any difference between that and what we have on ARM64 or the multiplatform > subset of ARM32. > > I don't think you need any strict architecture dependency here. If you want > to make it harder for users to accidentally turn it on, I'd suggest using > > config ACPI_REDUCED_HARDWARE_ONLY > bool "Hardware-reduced ACPI support only" > depends on !X86 || EXPERT > > Arnd Hrm. Seems a fair point. I'll respin the patch set to incorporate this, though now that I think of it I will add !IA64 since it is unlikely they'll do a reduced hardware platform any time soon and would have the same problem as x86. -- ciao, al ----------------------------------- Al Stone Software Engineer Red Hat, Inc. ahs3@redhat.com -----------------------------------