Commit 59bcdccc authored by Changbin Du's avatar Changbin Du Committed by Rafael J. Wysocki
Browse files

Documentation: ACPI: move initrd_table_override.txt to admin-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: default avatarChangbin Du <changbin.du@gmail.com>
Reviewed-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent eea78032

Documentation/admin-guide/acpi/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -8,3 +8,4 @@ the Linux ACPI support. 
.. toctree::

   :maxdepth: 1



   initrd_table_override

Documentation/acpi/initrd_table_override.txt→Documentation/admin-guide/acpi/initrd_table_override.rst

+115 −0
Original line number Diff line number Diff line 
.. SPDX-License-Identifier: GPL-2.0



================================

Upgrading ACPI tables via initrd

================================



1) Introduction (What is this about)

2) What is this for

3) How does it work

4) References (Where to retrieve userspace tools)



1) What is this about

---------------------

What is this about

==================



If the ACPI_TABLE_UPGRADE compile option is true, it is possible to

upgrade the ACPI execution environment that is defined by the ACPI tables
@@ -19,17 +17,20 @@ ACPI_TABLE_OVERRIDE_VIA_BUILTIN_INITRD should also be true for this 
feature to work.



For a full list of ACPI tables that can be upgraded/installed, take a look

at the char *table_sigs[MAX_ACPI_SIGNATURE]; definition in

at the char `*table_sigs[MAX_ACPI_SIGNATURE];` definition in

drivers/acpi/tables.c.



All ACPI tables iasl (Intel's ACPI compiler and disassembler) knows should

be overridable, except:



  - ACPI_SIG_RSDP (has a signature of 6 bytes)

  - ACPI_SIG_FACS (does not have an ordinary ACPI table header)



Both could get implemented as well.





2) What is this for

-------------------

What is this for

================



Complain to your platform/BIOS vendor if you find a bug which is so severe

that a workaround is not accepted in the Linux kernel. And this facility
@@ -47,8 +48,9 @@ It can and should be enabled in any kernel because there is no functional 
change with not instrumented initrds.





3) How does it work

-------------------

How does it work

================

::



  # Extract the machine's ACPI tables:

  cd /tmp
@@ -96,16 +98,18 @@ iasl is able to disassemble and recompile quite a lot different, 
also static ACPI tables.





4) Where to retrieve userspace tools

------------------------------------

Where to retrieve userspace tools

=================================



iasl and acpixtract are part of Intel's ACPICA project:

http://acpica.org/



and should be packaged by distributions (for example in the acpica package

on SUSE).



acpidump can be found in Len Browns pmtools:

ftp://kernel.org/pub/linux/kernel/people/lenb/acpi/utils/pmtools/acpidump



This tool is also part of the acpica package on SUSE.

Alternatively, used ACPI tables can be retrieved via sysfs in latest kernels:

/sys/firmware/acpi/tables

CRA Git | Maintained and supported by SUSTech CRA and CCSE