[PATCH] arm64/acpi: make ACPI boot preference configurable

On Wed, Feb 28, 2018 at 3:37 PM, Andy Shevchenko
[off-list ref] wrote:

On Wed, 2018-02-28 at 00:29 +0530, Bhupesh Sharma wrote:

quoted

On Tue, Feb 27, 2018 at 8:14 PM, Jonathan Toppins <jtoppins@redhat.com

quoted

wrote:
On 02/27/2018 07:40 AM, Bhupesh Sharma wrote:

quoted

quoted

quoted

For arm64 DT is suppose to *not* be the preferred method, yet still
DT
is preferred if the firmware provides both tables to the kernel.

quoted

However several arm64 products in embedded applications are still not
SBSA/SBBR compliant (and I have worked on a couple of such
implementations earlier) and still use bootloaders like u-boot (and
also closed-source implementations) which have no support for ACPI
currently and still rely on a DT to pass the system hardware
information to the kernel.

quoted

So far only open source implementation of a ACPI compliant firmware is
EDK2/UEFI which supports ACPI as the preferred boot method

You mean for non-x86?

Yes the patch in discussion is for arm64. So my comments above are in
context to arm64.

quoted

 and I am
not sure if all u-boot/in-house firmware implementations are planned
to be ported over to EDK2/UEFI for embedded applications.

Why do you need that? ACPI (if you are talking about ACPI only, w/o EFI)
is supported in U-Boot for few x86 SoCs/platforms. Moreover, one of them
had never been shipped with ACPI/EFI complaint services in firmware and
ACPI layer is purely done in U-Boot.

AFAIK upstream arm64 u-boot doesn't support ACPI boot method for
armv8/arm64 yet.

Regards,
Bhupesh