Commit 997c798e authored by Stephen Kitt's avatar Stephen Kitt Committed by Jonathan Corbet
Browse files

docs: sysctl/kernel: document unaligned controls 



This documents ignore-unaligned-usertrap, unaligned-dump-stack, and
unaligned-trap, based on arch/arc/kernel/unaligned.c,
arch/ia64/kernel/unaligned.c, and arch/parisc/kernel/unaligned.c.

While we're at it, integrate unaligned-memory-access.txt into the docs
tree.

Signed-off-by: default avatarStephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200515212443.5012-1-steve@sk2.org


Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 4eb92411

Documentation/admin-guide/sysctl/kernel.rst

+51 −0
Original line number Diff line number Diff line
@@ -402,6 +402,25 @@ Controls whether the panic kmsg data should be reported to Hyper-V. 
= =========================================================





ignore-unaligned-usertrap

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



On architectures where unaligned accesses cause traps, and where this

feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN``;

currently, ``arc`` and ``ia64``), controls whether all unaligned traps

are logged.



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

0 Log all unaligned accesses.

1 Only warn the first time a process traps. This is the default

  setting.

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



See also `unaligned-trap`_ and `unaligned-dump-stack`_. On ``ia64``,

this allows system administrators to override the

``IA64_THREAD_UAC_NOPRINT`` ``prctl`` and avoid logs being flooded.





kexec_load_disabled

===================
@@ -1261,6 +1280,38 @@ See :doc:`/admin-guide/kernel-parameters` and 
:doc:`/trace/boottime-trace`.





.. _unaligned-dump-stack:



unaligned-dump-stack (ia64)

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



When logging unaligned accesses, controls whether the stack is

dumped.



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

0 Do not dump the stack. This is the default setting.

1 Dump the stack.

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



See also `ignore-unaligned-usertrap`_.





unaligned-trap

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



On architectures where unaligned accesses cause traps, and where this

feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW``; currently,

``arc`` and ``parisc``), controls whether unaligned traps are caught

and emulated (instead of failing).



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

0 Do not emulate unaligned accesses.

1 Emulate unaligned accesses. This is the default setting.

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



See also `ignore-unaligned-usertrap`_.





unknown_nmi_panic

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

Documentation/process/index.rst

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@@ -61,6 +61,7 @@ lack of a better place. 
   botching-up-ioctls

   clang-format

   ../riscv/patch-acceptance

   unaligned-memory-access



.. only::  subproject and html