-----Original Message-----
From: Catalin Marinas [mailto:catalin.marinas at arm.com]
Sent: 06 January 2015 14:17
To: Arnd Bergmann
Cc: linux-arm-kernel at lists.infradead.org; hanjun.guo at linaro.org; Mark
Rutland; linaro-acpi at lists.linaro.org; Will Deacon; Lv Zheng; Rob
Herring; Lorenzo Pieralisi; Al Stone; Daniel Lezcano; Robert Moore;
linux-acpi at vger.kernel.org; jcm at redhat.com; grant.likely at linaro.org;
Charles Garcia-Tobin; Robert Richter; Jason Cooper; Marc Zyngier; Liviu
Dudau; Mark Brown; Bjorn Helgaas; graeme.gregory at linaro.org;
Kangkang.Shen at huawei.com; Randy Dunlap; Rafael J. Wysocki; linux-
kernel at vger.kernel.org; Sudeep Holla; Olof Johansson
Subject: Re: [PATCH v5 18/18] Documentation: ACPI for ARM64

On Tue, Jan 06, 2015 at 02:05:12PM +0000, Arnd Bergmann wrote:

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On Tuesday 06 January 2015 11:29:29 Catalin Marinas wrote:

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We will work on this both on ASWG and linux ACPI driver side,

as Dong

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and Charles pointed out, _OSI things can be solved in ACPI

spec, when

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that is done, we can modify the kernel driver to fix the

problems above.

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Which driver?

the ACPICA core driver as you suggested, sorry for the confusion.

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What about ACPI_OS_NAME? Would you suggest it is fine to report
"Microsoft Windows NT" on an ARM system? That _OS_ not _OSI.

No, not at all. I prefer "Linux"
In include/acpi/acconfig.h, when ACPI_OS_NAME defined, it says:
"OS name, used for the _OS object.  The _OS object is essentially
obsolete,..."
for some legacy reasons, we needed  "Microsoft Windows NT", but

ACPI

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for ARM64 on linux is totally new, I think we can change it to
"Linux" when CONFIG_ARM64 as you suggested.

We could ignore this change for now if we don't expect the _OS

object to

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be used at all. But do we have any other way to check the AML code

for

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this? Would FWTS catch such obsolete cases?

How about just leaving it out? It's clearly not used for anything
good, so I don't see the point in passing either Linux or "Microsoft
Windows NT" here.

Do you mean defining it to NULL (so it ends up as NULL in
acpi_gbl_pre_defined_names) or removing "_OS_" entirely from that
array?
I really can't tell what the implications are.

To me, given that we don't want to use it in ARM64, it would make sense to
have some method to configurably:
0. Leave as is
1. Warn for usage
2. Panic
With a configurability method that allows FWTS to make use of it, and
therefore catch usages of the method.

Cheers

Charles

--
Catalin