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Documentation: ACPI: move osi.txt to firmware-guide/acpi and convert to reST 

This converts the plain text documentation to reStructuredText format
and adds it to Sphinx TOC tree.

No essential content change.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Changbin Du 2019-04-25 01:52:46 +08:00 committed by Rafael J. Wysocki
parent c24bc66e81
commit 1cf70ae6f0
2 changed files with 10 additions and 6 deletions
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1
Documentation/firmware-guide/acpi/index.rst
View File

@ -9,3 +9,4 @@ ACPI Support
namespace
enumeration
osi

15
Documentation/acpi/osi.txt → Documentation/firmware-guide/acpi/osi.rst
View File

@ -1,5 +1,8 @@
.. SPDX-License-Identifier: GPL-2.0
==========================
ACPI _OSI and _REV methods
--------------------------
==========================
An ACPI BIOS can use the "Operating System Interfaces" method (_OSI)
to find out what the operating system supports. Eg. If BIOS
@ -14,7 +17,7 @@ This document explains how and why the BIOS and Linux should use these methods.
It also explains how and why they are widely misused.
How to use _OSI
---------------
===============
Linux runs on two groups of machines -- those that are tested by the OEM
to be compatible with Linux, and those that were never tested with Linux,
@ -62,7 +65,7 @@ the string when that support is added to the kernel.
That was easy. Read on, to find out how to do it wrong.
Before _OSI, there was _OS
--------------------------
==========================
ACPI 1.0 specified "_OS" as an
"object that evaluates to a string that identifies the operating system."
@ -96,7 +99,7 @@ That is the *only* viable strategy, as that is what modern Windows does,
and so doing otherwise could steer the BIOS down an untested path.
_OSI is born, and immediately misused
--------------------------------------
=====================================
With _OSI, the *BIOS* provides the string describing an interface,
and asks the OS: "YES/NO, are you compatible with this interface?"
@ -144,7 +147,7 @@ catastrophic failure resulting from the BIOS taking paths that
were never validated under *any* OS.
Do not use _REV
---------------
===============
Since _OSI("Linux") went away, some BIOS writers used _REV
to support Linux and Windows differences in the same BIOS.
@ -164,7 +167,7 @@ from mid-2015 onward. The ACPI specification will also be updated
to reflect that _REV is deprecated, and always returns 2.
Apple Mac and _OSI("Darwin")
----------------------------
============================
On Apple's Mac platforms, the ACPI BIOS invokes _OSI("Darwin")
to determine if the machine is running Apple OSX.