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authorLinus Torvalds <torvalds@linux-foundation.org>2026-04-14 08:47:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-04-14 08:47:08 -0700
commit5181afcdf99527dd92a88f80fc4d0d8013e1b510 (patch)
tree8c6922c93b0c4c274269d8e84fc2b0ae9f4fd5bd /Documentation/admin-guide/sysctl
parentd60bc140158342716e13ff0f8aa65642f43ba053 (diff)
parent40a3f6c5e2604ff7c007da6628120529569e950c (diff)
Merge tag 'docs-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/docs/linux
Pull documentation updates from Jonathan Corbet: "A busier cycle than I had expected for docs, including: - Translations: some overdue updates to the Japanese translations, Chinese translations for some of the Rust documentation, and the beginnings of a Portuguese translation. - New documents covering CPU isolation, managed interrupts, debugging Python gbb scripts, and more. - More tooling work from Mauro, reducing docs-build warnings, adding self tests, improving man-page output, bringing in a proper C tokenizer to replace (some of) the mess of kernel-doc regexes, and more. - Update and synchronize changes.rst and scripts/ver_linux, and put both into alphabetical order. ... and a long list of documentation updates, typo fixes, and general improvements" * tag 'docs-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/docs/linux: (162 commits) Documentation: core-api: real-time: correct spelling doc: Add CPU Isolation documentation Documentation: Add managed interrupts Documentation: seq_file: drop 2.6 reference docs/zh_CN: update rust/index.rst translation docs/zh_CN: update rust/quick-start.rst translation docs/zh_CN: update rust/coding-guidelines.rst translation docs/zh_CN: update rust/arch-support.rst translation docs/zh_CN: sync process/2.Process.rst with English version docs/zh_CN: fix an inconsistent statement in dev-tools/testing-overview tracing: Documentation: Update histogram-design.rst for fn() handling docs: sysctl: Add documentation for /proc/sys/xen/ Docs: hid: intel-ish-hid: make long URL usable Documentation/kernel-parameters: fix architecture alignment for pt, nopt, and nobypass sched/doc: Update yield_task description in sched-design-CFS Documentation/rtla: Convert links to RST format docs: fix typos and duplicated words across documentation docs: fix typo in zoran driver documentation docs: add an Assisted-by mention to submitting-patches.rst Revert "scripts/checkpatch: add Assisted-by: tag validation" ...
Diffstat (limited to 'Documentation/admin-guide/sysctl')
-rw-r--r--Documentation/admin-guide/sysctl/crypto.rst47
-rw-r--r--Documentation/admin-guide/sysctl/debug.rst52
-rw-r--r--Documentation/admin-guide/sysctl/index.rst9
-rw-r--r--Documentation/admin-guide/sysctl/xen.rst31
4 files changed, 136 insertions, 3 deletions
diff --git a/Documentation/admin-guide/sysctl/crypto.rst b/Documentation/admin-guide/sysctl/crypto.rst
new file mode 100644
index 000000000000..b707bd314a64
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/crypto.rst
@@ -0,0 +1,47 @@
+=================
+/proc/sys/crypto/
+=================
+
+These files show up in ``/proc/sys/crypto/``, depending on the
+kernel configuration:
+
+.. contents:: :local:
+
+fips_enabled
+============
+
+Read-only flag that indicates whether FIPS mode is enabled.
+
+- ``0``: FIPS mode is disabled (default).
+- ``1``: FIPS mode is enabled.
+
+This value is set at boot time via the ``fips=1`` kernel command line
+parameter. When enabled, the cryptographic API will restrict the use
+of certain algorithms and perform self-tests to ensure compliance with
+FIPS (Federal Information Processing Standards) requirements, such as
+FIPS 140-2 and the newer FIPS 140-3, depending on the kernel
+configuration and the module in use.
+
+fips_name
+=========
+
+Read-only file that contains the name of the FIPS module currently in use.
+The value is typically configured via the ``CONFIG_CRYPTO_FIPS_NAME``
+kernel configuration option.
+
+fips_version
+============
+
+Read-only file that contains the version string of the FIPS module.
+If ``CONFIG_CRYPTO_FIPS_CUSTOM_VERSION`` is set, it uses the value from
+``CONFIG_CRYPTO_FIPS_VERSION``. Otherwise, it defaults to the kernel
+release version (``UTS_RELEASE``).
+
+Copyright (c) 2026, Shubham Chakraborty <chakrabortyshubham66@gmail.com>
+
+For general info and legal blurb, please look in
+Documentation/admin-guide/sysctl/index.rst.
+
+.. See scripts/check-sysctl-docs to keep this up to date:
+.. scripts/check-sysctl-docs -vtable="crypto" \
+.. $(git grep -l register_sysctl_)
diff --git a/Documentation/admin-guide/sysctl/debug.rst b/Documentation/admin-guide/sysctl/debug.rst
new file mode 100644
index 000000000000..506bd5e48594
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/debug.rst
@@ -0,0 +1,52 @@
+================
+/proc/sys/debug/
+================
+
+These files show up in ``/proc/sys/debug/``, depending on the
+kernel configuration:
+
+.. contents:: :local:
+
+exception-trace
+===============
+
+This flag controls whether the kernel prints information about unhandled
+signals (like segmentation faults) to the kernel log (``dmesg``).
+
+- ``0``: Unhandled signals are not traced.
+- ``1``: Information about unhandled signals is printed.
+
+The default value is ``1`` on most architectures (like x86, MIPS, RISC-V),
+but it is ``0`` on **arm64**.
+
+The actual information printed and the context provided varies
+significantly depending on the CPU architecture. For example:
+
+- On **x86**, it typically prints the instruction pointer (IP), error
+ code, and address that caused a page fault.
+- On **PowerPC**, it may print the next instruction pointer (NIP),
+ link register (LR), and other relevant registers.
+
+When enabled, this feature is often rate-limited to prevent the kernel
+log from being flooded during a crash loop.
+
+kprobes-optimization
+====================
+
+This flag enables or disables the optimization of Kprobes on certain
+architectures (like x86).
+
+- ``0``: Kprobes optimization is turned off.
+- ``1``: Kprobes optimization is turned on (default).
+
+For more details on Kprobes and its optimization, please refer to
+Documentation/trace/kprobes.rst.
+
+Copyright (c) 2026, Shubham Chakraborty <chakrabortyshubham66@gmail.com>
+
+For general info and legal blurb, please look in
+Documentation/admin-guide/sysctl/index.rst.
+
+.. See scripts/check-sysctl-docs to keep this up to date:
+.. scripts/check-sysctl-docs -vtable="debug" \
+.. $(git grep -l register_sysctl_)
diff --git a/Documentation/admin-guide/sysctl/index.rst b/Documentation/admin-guide/sysctl/index.rst
index 4dd2c9b5d752..50f00514f0ff 100644
--- a/Documentation/admin-guide/sysctl/index.rst
+++ b/Documentation/admin-guide/sysctl/index.rst
@@ -67,8 +67,8 @@ This documentation is about:
=============== ===============================================================
abi/ execution domains & personalities
<$ARCH> tuning controls for various CPU architecture (e.g. csky, s390)
-crypto/ <undocumented>
-debug/ <undocumented>
+crypto/ cryptographic subsystem
+debug/ debugging features
dev/ device specific information (e.g. dev/cdrom/info)
fs/ specific filesystems
filehandle, inode, dentry and quota tuning
@@ -84,7 +84,7 @@ sunrpc/ SUN Remote Procedure Call (NFS)
user/ Per user namespace limits
vm/ memory management tuning
buffer and cache management
-xen/ <undocumented>
+xen/ Xen hypervisor controls
=============== ===============================================================
These are the subdirs I have on my system or have been discovered by
@@ -96,9 +96,12 @@ it :-)
:maxdepth: 1
abi
+ crypto
+ debug
fs
kernel
net
sunrpc
user
vm
+ xen
diff --git a/Documentation/admin-guide/sysctl/xen.rst b/Documentation/admin-guide/sysctl/xen.rst
new file mode 100644
index 000000000000..6c5edc3e5e4c
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/xen.rst
@@ -0,0 +1,31 @@
+===============
+/proc/sys/xen/
+===============
+
+Copyright (c) 2026, Shubham Chakraborty <chakrabortyshubham66@gmail.com>
+
+For general info and legal blurb, please look in
+Documentation/admin-guide/sysctl/index.rst.
+
+------------------------------------------------------------------------------
+
+These files show up in ``/proc/sys/xen/``, depending on the
+kernel configuration:
+
+.. contents:: :local:
+
+balloon/hotplug_unpopulated
+===========================
+
+This flag controls whether unpopulated memory ranges are automatically
+hotplugged as system RAM.
+
+- ``0``: Unpopulated ranges are not hotplugged (default).
+- ``1``: Unpopulated ranges are automatically hotplugged.
+
+When enabled, the Xen balloon driver will add memory regions that are
+marked as unpopulated in the Xen memory map to the system as usable RAM.
+This allows for dynamic memory expansion in Xen guest domains.
+
+This option is only available when the kernel is built with
+``CONFIG_XEN_BALLOON_MEMORY_HOTPLUG`` enabled.