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author | Stephen Kitt <steve@sk2.org> | 2020-05-15 23:24:44 +0200 |
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committer | Jonathan Corbet <corbet@lwn.net> | 2020-05-25 18:59:59 -0600 |
commit | 997c798e1444ad02e8af8b18c869fff5c61867da (patch) | |
tree | c59a8893adf9e6484c714e8faa9aa22407e64a5e /Documentation | |
parent | 4eb9241127a0b5ac3aaaf1b246728009527ebc86 (diff) | |
download | lwn-997c798e1444ad02e8af8b18c869fff5c61867da.tar.gz lwn-997c798e1444ad02e8af8b18c869fff5c61867da.zip |
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: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200515212443.5012-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 51 | ||||
-rw-r--r-- | Documentation/process/index.rst | 1 | ||||
-rw-r--r-- | Documentation/process/unaligned-memory-access.rst (renamed from Documentation/unaligned-memory-access.txt) | 0 |
3 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 6b313b6d42d5..4752d9a79235 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -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 ================= diff --git a/Documentation/process/index.rst b/Documentation/process/index.rst index 6399d92f0b21..f07c9250c3ac 100644 --- a/Documentation/process/index.rst +++ b/Documentation/process/index.rst @@ -61,6 +61,7 @@ lack of a better place. botching-up-ioctls clang-format ../riscv/patch-acceptance + unaligned-memory-access .. only:: subproject and html diff --git a/Documentation/unaligned-memory-access.txt b/Documentation/process/unaligned-memory-access.rst index 1ee82419d8aa..1ee82419d8aa 100644 --- a/Documentation/unaligned-memory-access.txt +++ b/Documentation/process/unaligned-memory-access.rst |