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

.. toctree::

   :maxdepth: 1

   :maxdepth: 1





   initrd_table_override

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

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



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

Upgrading ACPI tables via initrd

Upgrading ACPI tables via initrd

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

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





1) Introduction (What is this about)

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

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





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

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

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.

feature to work.





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

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.

drivers/acpi/tables.c.



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

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

be overridable, except:

be overridable, except:



  - ACPI_SIG_RSDP (has a signature of 6 bytes)

  - ACPI_SIG_RSDP (has a signature of 6 bytes)

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

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



Both could get implemented as well.

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

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

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.

change with not instrumented initrds.









3) How does it work

How does it work

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

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

::





  # Extract the machine's ACPI tables:

  # Extract the machine's ACPI tables:

  cd /tmp

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

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:

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

http://acpica.org/

http://acpica.org/



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

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

on SUSE).

on SUSE).





acpidump can be found in Len Browns pmtools:

acpidump can be found in Len Browns pmtools:

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

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



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

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

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

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

/sys/firmware/acpi/tables
 
/sys/firmware/acpi/tables