From patchwork Wed Jan 8 00:46:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: al.stone@linaro.org X-Patchwork-Id: 3450971 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 311FEC02DC for ; Wed, 8 Jan 2014 00:50:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 499FB20122 for ; Wed, 8 Jan 2014 00:50:50 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4F89B20121 for ; Wed, 8 Jan 2014 00:50:49 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W0hKB-0002Ct-7I; Wed, 08 Jan 2014 00:48:48 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W0hJj-00009c-Uq; Wed, 08 Jan 2014 00:48:19 +0000 Received: from mail-ig0-f179.google.com ([209.85.213.179]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W0hIy-0008UA-D1 for linux-arm-kernel@lists.infradead.org; Wed, 08 Jan 2014 00:47:36 +0000 Received: by mail-ig0-f179.google.com with SMTP id hk11so3219688igb.0 for ; Tue, 07 Jan 2014 16:47:04 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=39FMEb5jnA1LVpmNhQZR8BuAc5nYz9CsWr208nTpDO4=; b=heTRXOOD+ZOyltJ4dfbAOF163YhQRDIsS8OleGu9IB2LkcceKVki7SE44HsyDqntSz a8Sfa4trjLz8LHvDI6MSaZprmL13Ut4gNj4XWxZC3GlgxTTQAxFB7vgDip9R65DVx/Sz +nj4yLHMIbCc3GZ2LUidc2fHSLdNg9nDv1ZkL2nk23B50xP8tk+U14b48zdbH0/ft8mn gxiDrHD9dGxYoAovXHGhiOxYee5K/VXwpe6uZupd86JQC+jHTUZAMpfPei8tABOJUGIA PzyjYZucYTK4pvzJiAHnGLQms3kurltnJBvv0Nlbc6i44nWHGxnrSnI9iRmpIVVWdEFF oP8A== X-Gm-Message-State: ALoCoQlll/o1uKH5wogBCxfNJfkp76F5epkXiP3ETOTlHR8htzKOLEjo/tvmOESX7shdBJtX9I9B X-Received: by 10.42.171.6 with SMTP id h6mr10956760icz.62.1389142024401; Tue, 07 Jan 2014 16:47:04 -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 kt2sm6361770igb.1.2014.01.07.16.47.03 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Jan 2014 16:47:03 -0800 (PST) From: al.stone@linaro.org To: linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v5 1/5] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE_ONLY to enforce this ACPI mode Date: Tue, 7 Jan 2014 17:46:47 -0700 Message-Id: <1389142011-27356-2-git-send-email-al.stone@linaro.org> X-Mailer: git-send-email 1.8.4.2 In-Reply-To: <1389142011-27356-1-git-send-email-al.stone@linaro.org> References: <1389142011-27356-1-git-send-email-al.stone@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140107_194732_519544_E853C865 X-CRM114-Status: GOOD ( 19.39 ) X-Spam-Score: -0.1 (/) Cc: Hanjun Guo , patches@linaro.org, Al Stone , linaro-kernel@lists.linaro.org, linaro-acpi@lists.linaro.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, SUSPICIOUS_RECIPS, UNPARSEABLE_RELAY autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 | 12 ++++++++++++ include/acpi/platform/aclinux.h | 6 ++++++ 2 files changed, 18 insertions(+) diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 4770de5..1199087 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -343,6 +343,18 @@ 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" + depends on ARM || ARM64 + 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