Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761138AbcLURyU (ORCPT ); Wed, 21 Dec 2016 12:54:20 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57384 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761049AbcLURyT (ORCPT ); Wed, 21 Dec 2016 12:54:19 -0500 From: Jonathan Toppins To: linux-arm-kernel@lists.infradead.org Cc: msalter@redhat.com, Catalin Marinas , Will Deacon , Stefano Stabellini , Hanjun Guo , Mark Rutland , Shannon Zhao , Aleksey Makarov , Ard Biesheuvel , linux-kernel@vger.kernel.org Subject: [RFC] arm64/acpi: make ACPI boot preference configurable Date: Wed, 21 Dec 2016 12:54:05 -0500 Message-Id: <7eba0601099f75f19021c4259eca75ada06f4511.1482341997.git.jtoppins@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Wed, 21 Dec 2016 17:54:18 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2265 Lines: 56 This patch allows a user to configure ACPI to be preferred over device-tree. Currently for ACPI to be used a user either has to set acpi=on on the kernel command line or make sure any device tree passed to the kernel is empty. If the dtb passed to the kernel is non-empty then device-tree will be chosen as the boot method of choice even if it is not correct. To prevent this situation where a system is only intended to be booted via ACPI a user can set this kernel configuration so it ignores device-tree settings unless ACPI table checks fail. Signed-off-by: Jonathan Toppins --- arch/arm64/Kconfig | 13 +++++++++++++ arch/arm64/kernel/acpi.c | 2 +- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 111742126897..e432e84245b9 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -954,6 +954,19 @@ config ARM64_ACPI_PARKING_PROTOCOL protocol even if the corresponding data is present in the ACPI MADT table. +config ARM64_PREFER_ACPI + bool "Prefer usage of ACPI boot tables over device-tree" + depends on ACPI + help + Normally device-tree is preferred over ACPI on arm64 unless + explicitly preferred via kernel command line, something like: acpi=on + This configuration changes this default behaviour by pretending + the user set acpi=on on the command line. This configuration still + allows the user to turn acpi table parsing off via acpi=off. If + for some reason the table checks fail the system will still fall + back to using device-tree unless the user explicitly sets acpi=force + on the command line. + config CMDLINE string "Default kernel command string" default "" diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 252a6d9c1da5..b5dfa5752ff7 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -43,7 +43,7 @@ int acpi_pci_disabled = 1; /* skip ACPI PCI scan and IRQ initialization */ EXPORT_SYMBOL(acpi_pci_disabled); static bool param_acpi_off __initdata; -static bool param_acpi_on __initdata; +static bool param_acpi_on __initdata = IS_ENABLED(CONFIG_ARM64_PREFER_ACPI); static bool param_acpi_force __initdata; static int __init parse_acpi(char *arg) -- 2.10.2