From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Tue, 12 Apr 2016 14:35:55 +0100 Subject: [PATCH] arm64: acpi: add a Kconfig option to prefer ACPI boot over DT In-Reply-To: References: <1460373568-4374-1-git-send-email-ard.biesheuvel@linaro.org> <20160412130751.GA8066@e104818-lin.cambridge.arm.com> Message-ID: <20160412133555.GD8066@e104818-lin.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Apr 12, 2016 at 03:19:58PM +0200, Ard Biesheuvel wrote: > On 12 April 2016 at 15:07, Catalin Marinas wrote: > > On Mon, Apr 11, 2016 at 01:19:28PM +0200, Ard Biesheuvel wrote: > >> If both ACPI and DT platform descriptions are available, and the > >> kernel was configured at build time to support both flavours, the > >> default policy in absence of a acpi=[off|force] kernel command line > >> parameter is to prefer DT over ACPI. > >> > >> This adds an option to invert that default policy, and prefer ACPI > >> over DT instead. Note that this policy is still superseded by the > >> value of the acpi= command line parameter. > > > > Why do we need another method to specify an ACPI boot? I thought those > > vendors going for ACPI wouldn't be bothered with DT anyway. > > > > I'm not keen on having kernel builds with different behavior in respect > > of whether ACPI or DT is preferred. > > How about adding support for acpi=on then? Currently, we only have > acpi=off or acpi=force, and there is no way (i.e., for a distro > installer) to boot via ACPI if it can but fall back to DT otherwise. > Some enterprise features (like RAS) depend on ACPI boot so it may > simply preferred but not mandated in some cases. Since this is a distro preference, I would rather have an acpi=on option. -- Catalin