From patchwork Thu Jan 16 18:44:17 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Stone X-Patchwork-Id: 23275 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-qe0-f69.google.com (mail-qe0-f69.google.com [209.85.128.69]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id 4484C203C4 for ; Thu, 16 Jan 2014 18:44:34 +0000 (UTC) Received: by mail-qe0-f69.google.com with SMTP id 1sf4733463qec.8 for ; Thu, 16 Jan 2014 10:44:33 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:delivered-to:from:to:cc:subject :date:message-id:x-original-sender:x-original-authentication-results :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-unsubscribe; bh=AtUSY1uo41kN2BzogGIZ7Qv9STktTULTtE93/BnIBLA=; b=EjoOQnDs4U+Goj8uQdqS1lbVmNk/AKrhnjp8P5ccfraem/XWrhL+iAZba5OXtFmA3v KrkTzb7rgWJpHnYP515c8/UpGc9pw8niJLc9oGWMUl4K7URIbRHx0944HHzwcKgbv6VL StomSSQ+256DJHHgafWsJMA/HaidjLVEzbMTxTrINfNu6kXd1UKtC1pNJjN5hm76mPsY RGPLsglb0woqy9An02s/0hSHPdGxCb8MvBXgSqNZXV+kdwWSr3J924o6724sPLy+eeIk UqrzaMey+uEA6nG7Z/eu6oNU/E1YwJYXltClT3+8vT3UFungBLXSmUNPyRU+zJSQ0ncd tD3g== X-Gm-Message-State: ALoCoQm7PotcuMnLT/8sV0P/VD3OcG5p+CaZROXTmekn8VYKNx5508p0q3FFpXe1+13vrt8BkDO7 X-Received: by 10.236.110.3 with SMTP id t3mr3433294yhg.3.1389897873431; Thu, 16 Jan 2014 10:44:33 -0800 (PST) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.82.49 with SMTP id f17ls1001567qey.54.gmail; Thu, 16 Jan 2014 10:44:33 -0800 (PST) X-Received: by 10.52.157.38 with SMTP id wj6mr50284vdb.63.1389897873303; Thu, 16 Jan 2014 10:44:33 -0800 (PST) Received: from mail-vc0-f181.google.com (mail-vc0-f181.google.com [209.85.220.181]) by mx.google.com with ESMTPS id s10si3716072vco.131.2014.01.16.10.44.33 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 16 Jan 2014 10:44:33 -0800 (PST) Received-SPF: neutral (google.com: 209.85.220.181 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.220.181; Received: by mail-vc0-f181.google.com with SMTP id ie18so1159239vcb.12 for ; Thu, 16 Jan 2014 10:44:33 -0800 (PST) X-Received: by 10.52.117.176 with SMTP id kf16mr6485246vdb.6.1389897873026; Thu, 16 Jan 2014 10:44:33 -0800 (PST) X-Forwarded-To: patchwork-forward@linaro.org X-Forwarded-For: patch@linaro.org patchwork-forward@linaro.org Delivered-To: patches@linaro.org Received: by 10.59.13.131 with SMTP id ey3csp369848ved; Thu, 16 Jan 2014 10:44:32 -0800 (PST) X-Received: by 10.43.103.67 with SMTP id dh3mr9640545icc.60.1389897872103; Thu, 16 Jan 2014 10:44:32 -0800 (PST) Received: from mail-ie0-f180.google.com (mail-ie0-f180.google.com [209.85.223.180]) by mx.google.com with ESMTPS id aj4si13153710icc.27.2014.01.16.10.44.31 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 16 Jan 2014 10:44:31 -0800 (PST) Received-SPF: neutral (google.com: 209.85.223.180 is neither permitted nor denied by best guess record for domain of al.stone@linaro.org) client-ip=209.85.223.180; Received: by mail-ie0-f180.google.com with SMTP id at1so1186251iec.25 for ; Thu, 16 Jan 2014 10:44:31 -0800 (PST) X-Received: by 10.50.12.103 with SMTP id x7mr11342305igb.11.1389897871671; Thu, 16 Jan 2014 10:44:31 -0800 (PST) Received: from fidelio.ahs3 (74-93-232-46-Colorado.hfc.comcastbusiness.net. [74.93.232.46]) by mx.google.com with ESMTPSA id e2sm1584834igt.2.2014.01.16.10.44.30 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 Jan 2014 10:44:30 -0800 (PST) From: al.stone@linaro.org To: linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: linaro-acpi@lists.linaro.org, patches@linaro.org, linaro-kernel@lists.linaro.org, Al Stone , Hanjun Guo Subject: [PATCH v2] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE_ONLY to enforce this ACPI mode Date: Thu, 16 Jan 2014 11:44:17 -0700 Message-Id: <1389897857-1790-1-git-send-email-al.stone@linaro.org> X-Mailer: git-send-email 1.8.4.2 X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: al.stone@linaro.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 209.85.220.181 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Precedence: list Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org List-ID: X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , From: Al Stone Hardware reduced mode, despite the name, exists primarily to allow newer platforms to use a much simpler form of ACPI that does not require supporting the legacy of previous versions of the specification. This mode was first introduced in the ACPI 5.0 specification, but because it is so much simpler and reduces the size of the object code needed to support ACPI, it is likely to be used more often in the near future. To enable the hardware reduced mode of ACPI on some platforms (such as ARM), we need to modify the kernel code and set ACPI_REDUCED_HARDWARE to TRUE in the ACPICA source. For ARM/ARM64, hardware reduced ACPI should be the only mode used; legacy mode would require modifications to SoCs in order to provide several x86-specific hardware features (e.g., an NMI and SMI support). We set ACPI_REDUCED_HARDWARE to TRUE in the ACPICA source by introducing a kernel config item to enable/disable ACPI_REDUCED_HARDWARE. We can then change the kernel config instead of having to modify the kernel source directly to enable the reduced hardware mode of ACPI. Lv Zheng suggested that this configuration item does not belong in ACPICA, the upstream source for much of the ACPI internals, but rather to the Linux kernel itself. Hence, we introduce this flag so that we can make ACPI_REDUCED_HARDWARE configurable. For the details of the discussion, please refer to: http://www.spinics.net/lists/linux-acpi/msg46369.html 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. The problem with the current ACPICA code base is that if one builds legacy ACPI (a proper superset of hardware-reduced), the kernel can run in hardware- reduced with the proper ACPI tables, but there is still ACPICA code that could be executed even though it is not allowed by the specification. If one builds a hardware-reduced only ACPI, the kernel cannot run with ACPI tables that are for legacy mode. To ensure compliance with ACPI, one must therefore build two separate kernels. Once this problem has been properly fixed, we can then enable x86 hardware-reduced mode and use a single kernel. Changes for v2: -- Changed test for EXPERT to avoid reported Kconfig warning Signed-off-by: Hanjun Guo Signed-off-by: Al Stone --- drivers/acpi/Kconfig | 13 +++++++++++++ include/acpi/platform/aclinux.h | 6 ++++++ 2 files changed, 19 insertions(+) diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 4770de5..9fd6a7a 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -343,6 +343,19 @@ config ACPI_BGRT data from the firmware boot splash. It will appear under /sys/firmware/acpi/bgrt/ . +config ACPI_REDUCED_HARDWARE_ONLY + bool "Hardware-reduced ACPI support only" if EXPERT + def_bool n + depends on ACPI + help + This config item changes the way the ACPI code is built. When this + option is selected, the kernel will use a specialized version of + ACPICA that ONLY supports the ACPI "reduced hardware" mode. The + resulting kernel will be smaller but it will also be restricted to + running in ACPI reduced hardware mode ONLY. + + If you are unsure what to do, do not enable this option. + source "drivers/acpi/apei/Kconfig" config ACPI_EXTLOG diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h index 28f4f4d..7d71f08 100644 --- a/include/acpi/platform/aclinux.h +++ b/include/acpi/platform/aclinux.h @@ -52,6 +52,12 @@ #ifdef __KERNEL__ +/* Compile for reduced hardware mode only with this kernel config */ + +#ifdef CONFIG_ACPI_REDUCED_HARDWARE_ONLY +#define ACPI_REDUCED_HARDWARE 1 +#endif + #include #include #include