From patchwork Tue Dec 17 00:16:37 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Stone X-Patchwork-Id: 22545 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-qc0-f197.google.com (mail-qc0-f197.google.com [209.85.216.197]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id ACCB223FF1 for ; Tue, 17 Dec 2013 00:16:53 +0000 (UTC) Received: by mail-qc0-f197.google.com with SMTP id r5sf10053677qcx.0 for ; Mon, 16 Dec 2013 16:16:53 -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:in-reply-to:references:x-original-sender :x-original-authentication-results:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-unsubscribe; bh=kyQ7A6e/Upa6NttzsmzXrDJaNmF68zDZTlVixfnmPOY=; b=jnkIFWKbNqlj3BwtnQgachzr5yyivIzp8/fYxJJ1L5RFJvn73lRJozKGDrWBlqi/Ie +IWVCebD9D9TgH3/qV5SGMML7nwZKjwtGlSp3raYLI0C+H+4dYVyHH8o9YhU9g3aRkta gDweU3JdvI18KLHcs2LEntxsFwMoEzTiFZcMkKD7gwy16+W6CUCvtF0+E8izySHGhUdE /AULeVZK0JZejWEvEazn42yhUyKmDgTS0Wq8wRw+g4t30435KQl9AJzPX/5oocbkQRH5 YqrmP1OZFZ7EQD1wwR8U6vm5tBfudRpvtVLBg2aZTyHVB/gjAe/sE8e/jZgq/2/t6VgY rCpA== X-Gm-Message-State: ALoCoQk1kfHwIqcydm17z+XL/cxCAlipabfFQfNoR/BH7I/kNxK8LN83Jt/54uISgqsvU1AkQUdb X-Received: by 10.236.21.132 with SMTP id r4mr6799665yhr.7.1387239413469; Mon, 16 Dec 2013 16:16:53 -0800 (PST) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.47.9 with SMTP id z9ls2287755qem.79.gmail; Mon, 16 Dec 2013 16:16:53 -0800 (PST) X-Received: by 10.221.18.70 with SMTP id qf6mr3547347vcb.37.1387239413362; Mon, 16 Dec 2013 16:16:53 -0800 (PST) Received: from mail-vc0-f172.google.com (mail-vc0-f172.google.com [209.85.220.172]) by mx.google.com with ESMTPS id df13si3453561vec.148.2013.12.16.16.16.53 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 16 Dec 2013 16:16:53 -0800 (PST) Received-SPF: neutral (google.com: 209.85.220.172 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.220.172; Received: by mail-vc0-f172.google.com with SMTP id ij19so3716253vcb.3 for ; Mon, 16 Dec 2013 16:16:53 -0800 (PST) X-Received: by 10.52.241.105 with SMTP id wh9mr13582vdc.83.1387239413208; Mon, 16 Dec 2013 16:16:53 -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 10.220.174.196 with SMTP id u4csp29237vcz; Mon, 16 Dec 2013 16:16:52 -0800 (PST) X-Received: by 10.42.179.195 with SMTP id br3mr4235670icb.21.1387239412249; Mon, 16 Dec 2013 16:16:52 -0800 (PST) Received: from mail-ig0-f176.google.com (mail-ig0-f176.google.com [209.85.213.176]) by mx.google.com with ESMTPS id c13si12221064igo.62.2013.12.16.16.16.52 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 16 Dec 2013 16:16:52 -0800 (PST) Received-SPF: neutral (google.com: 209.85.213.176 is neither permitted nor denied by best guess record for domain of al.stone@linaro.org) client-ip=209.85.213.176; Received: by mail-ig0-f176.google.com with SMTP id k19so5043309igc.3 for ; Mon, 16 Dec 2013 16:16:52 -0800 (PST) X-Received: by 10.43.124.134 with SMTP id go6mr116143icc.84.1387239411933; Mon, 16 Dec 2013 16:16:51 -0800 (PST) Received: from fidelio.ahs3.com (74-93-232-46-Colorado.hfc.comcastbusiness.net. [74.93.232.46]) by mx.google.com with ESMTPSA id j3sm12877632igj.9.2013.12.16.16.16.50 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 16 Dec 2013 16:16:51 -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 v4 1/5] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE to enable this ACPI mode Date: Mon, 16 Dec 2013 17:16:37 -0700 Message-Id: <1387239401-13918-2-git-send-email-al.stone@linaro.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1387239401-13918-1-git-send-email-al.stone@linaro.org> References: <1387239401-13918-1-git-send-email-al.stone@linaro.org> 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: 209.85.220.172 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. Signed-off-by: Hanjun Guo Signed-off-by: Al Stone --- drivers/acpi/Kconfig | 8 ++++++++ include/acpi/platform/aclinux.h | 6 ++++++ 2 files changed, 14 insertions(+) diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 5d92485..53f0f16 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -343,6 +343,14 @@ config ACPI_BGRT data from the firmware boot splash. It will appear under /sys/firmware/acpi/bgrt/ . +config ACPI_REDUCED_HARDWARE + bool "Hardware-reduced ACPI support" + depends on ARM || ARM64 + help + This config adds support for Hardware-reduced ACPI. When this option + is selected, will generate a specialized version of ACPICA that ONLY + supports the ACPI "reduced hardware". + source "drivers/acpi/apei/Kconfig" config ACPI_EXTLOG diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h index 28f4f4d..a33f502 100644 --- a/include/acpi/platform/aclinux.h +++ b/include/acpi/platform/aclinux.h @@ -52,6 +52,12 @@ #ifdef __KERNEL__ +/* Compile for reduced hardware mode if requested for this kernel config */ + +#ifdef CONFIG_ACPI_REDUCED_HARDWARE +#define ACPI_REDUCED_HARDWARE 1 +#endif + #include #include #include