[PATCH] arm64: acpi: add a Kconfig option to prefer ACPI boot over DT

[Ard Biesheuvel]

On 12 April 2016 at 15:07, Catalin Marinas <catalin.marinas at arm.com> 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 Note that this policy is still superseded by the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.