From patchwork Tue Jan 14 20:37:02 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Stone X-Patchwork-Id: 23203 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-ie0-f198.google.com (mail-ie0-f198.google.com [209.85.223.198]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id 5D57B2066C for ; Tue, 14 Jan 2014 20:37:14 +0000 (UTC) Received: by mail-ie0-f198.google.com with SMTP id tp5sf2950917ieb.1 for ; Tue, 14 Jan 2014 12:37:13 -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=IH936ubzbALwMTSg6VU1pE21RkA+yBOTprw1lqYuCjo=; b=MNJewstKO5nCBfwzTlmQFn86RiA3dWwT17CpDH6WQcPmRZOXIKWcj6TTpnn47Nv6u6 I4jRkArmv8XeZ4K1lg4mKvn5zgjAkkYODX7zui5OP+p9URnQadjA+3AxYq0f3XnFjtzM yG/3SyxP9BOLsJ2A4aczn7owog/+TMBRon5uyKmUhwv1g/1RqM8Up2jLW8rwV8i/N+F8 14HQwEomqxZ9P2dgQkEQ2o7FqapqF6wU9YuwLIEH7ldUoJwm2dqswHP+sIYwKytpx8Cd b9uutfzl7V1mqbABycdw7RHd7ZQlOotFsplwDvcQfNhChzxUjyY1R56O5IHHj1eKplj4 QxBg== X-Gm-Message-State: ALoCoQnBO/qrEwRt/fPFmv0n2N2WwnO3XuxEp+RKXGwuX00MzsQrT1SFaqVhbbL1XZ3MzlYSkhNG X-Received: by 10.182.161.105 with SMTP id xr9mr1337858obb.31.1389731833590; Tue, 14 Jan 2014 12:37:13 -0800 (PST) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.49.49.10 with SMTP id q10ls296948qen.0.gmail; Tue, 14 Jan 2014 12:37:13 -0800 (PST) X-Received: by 10.58.37.232 with SMTP id b8mr88778vek.27.1389731833495; Tue, 14 Jan 2014 12:37:13 -0800 (PST) Received: from mail-vc0-f171.google.com (mail-vc0-f171.google.com [209.85.220.171]) by mx.google.com with ESMTPS id ef6si633070ved.47.2014.01.14.12.37.13 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 14 Jan 2014 12:37:13 -0800 (PST) Received-SPF: neutral (google.com: 209.85.220.171 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.220.171; Received: by mail-vc0-f171.google.com with SMTP id le5so52963vcb.30 for ; Tue, 14 Jan 2014 12:37:13 -0800 (PST) X-Received: by 10.52.158.170 with SMTP id wv10mr584vdb.77.1389731833405; Tue, 14 Jan 2014 12:37:13 -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 ey3csp228422ved; Tue, 14 Jan 2014 12:37:12 -0800 (PST) X-Received: by 10.50.61.101 with SMTP id o5mr5077606igr.31.1389731832334; Tue, 14 Jan 2014 12:37:12 -0800 (PST) Received: from mail-ig0-f173.google.com (mail-ig0-f173.google.com [209.85.213.173]) by mx.google.com with ESMTPS id l3si3216230igx.53.2014.01.14.12.37.12 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 14 Jan 2014 12:37:12 -0800 (PST) Received-SPF: neutral (google.com: 209.85.213.173 is neither permitted nor denied by best guess record for domain of al.stone@linaro.org) client-ip=209.85.213.173; Received: by mail-ig0-f173.google.com with SMTP id c10so5992401igq.0 for ; Tue, 14 Jan 2014 12:37:12 -0800 (PST) X-Received: by 10.42.215.80 with SMTP id hd16mr295394icb.17.1389731831980; Tue, 14 Jan 2014 12:37:11 -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 qb4sm2924781igb.7.2014.01.14.12.37.10 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Jan 2014 12:37:11 -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] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE_ONLY to enforce this ACPI mode Date: Tue, 14 Jan 2014 13:37:02 -0700 Message-Id: <1389731822-21336-1-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: 209.85.220.171 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. This patch used to be part of a set to implement stricter conformance with hardware reduced ACPI. The code changes from that set are being re-thought in order to handle some non-compliant hardware, but this patch did not depend on those changes. In the meantime, this patch is needed in order to enable ACPI core functionality for ARMv8 servers and hence is being submitted separately in order to aid that effort. 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..961ea9e 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" + def_bool n + depends on ACPI && EXPERT + 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