From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hanjun Guo Subject: Re: [PATCH] ACPICA / hwreg: Use acpi_gbl_reduced_hardware to prevent accessing PM registers Date: Wed, 18 Sep 2013 17:31:32 +0800 Message-ID: <523972F4.9070703@linaro.org> References: <1379066741-23689-1-git-send-email-hanjun.guo@linaro.org> <94F2FBAB4432B54E8AACC7DFDE6C92E36FEEBC6A@ORSMSX103.amr.corp.intel.com> <94F2FBAB4432B54E8AACC7DFDE6C92E36FEEC15B@ORSMSX103.amr.corp.intel.com> <52366F91.30204@linaro.org> <94F2FBAB4432B54E8AACC7DFDE6C92E36FEEC56A@ORSMSX103.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pa0-f43.google.com ([209.85.220.43]:47985 "EHLO mail-pa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751881Ab3IRJeF (ORCPT ); Wed, 18 Sep 2013 05:34:05 -0400 Received: by mail-pa0-f43.google.com with SMTP id hz10so8021819pad.16 for ; Wed, 18 Sep 2013 02:34:04 -0700 (PDT) In-Reply-To: <94F2FBAB4432B54E8AACC7DFDE6C92E36FEEC56A@ORSMSX103.amr.corp.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Moore, Robert" Cc: "'Rafael J. Wysocki'" , 'Len Brown' , "Box, David E" , "Zheng, Lv" , "'linux-acpi@vger.kernel.org'" , "'patches@linaro.org'" , "'linaro-kernel@lists.linaro.org'" , "'linaro-acpi@lists.linaro.org'" On 2013-9-17 1:26, Moore, Robert wrote: > + #define ACPI_REDUCED_HARDWARE TRUE > > The intent of this feature is of course, to remove all code that is not needed -- specifically for hardware-reduced machines where the size of the kernel is important. > > On a larger machine, the hardware-reduced flag should be sufficient. However, I would think that the host OS would look at this flag and realize that it should not be doing certain ACPI hardware-related things up front, rather than later when it finds out that a write to some ACPI hardware fails because the hardware isn't there. Do you mean we should change the ACPI device driver instead of changing the ACPICA code? that would be a hard job, because hardware ACPI is used everywhere. Thanks Hanjun > > This is not to say that it is probably a good thing to return an error from the ACPI hardware code in the hardware-reduced case. > > Bob >