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Merge tag 'trace-ring-buffer-v6.12' of git://git.kernel.org/pub/scm/linux/kernel...
[linux.git] / Documentation / admin-guide / kernel-parameters.txt
index 9bb50dc78338275aa7456d13a0b53ff818541b85..bb48ae24ae69fa4d73ec91fadeddc3da0215e123 100644 (file)
                                          allowed anymore to lift isolation
                                          requirements as needed. This option
                                          does not override iommu=pt
-                       force_enable - Force enable the IOMMU on platforms known
-                                      to be buggy with IOMMU enabled. Use this
-                                      option with care.
-                       pgtbl_v1     - Use v1 page table for DMA-API (Default).
-                       pgtbl_v2     - Use v2 page table for DMA-API.
-                       irtcachedis  - Disable Interrupt Remapping Table (IRT) caching.
+                       force_enable    - Force enable the IOMMU on platforms known
+                                         to be buggy with IOMMU enabled. Use this
+                                         option with care.
+                       pgtbl_v1        - Use v1 page table for DMA-API (Default).
+                       pgtbl_v2        - Use v2 page table for DMA-API.
+                       irtcachedis     - Disable Interrupt Remapping Table (IRT) caching.
+                       nohugepages     - Limit page-sizes used for v1 page-tables
+                                         to 4 KiB.
+                       v2_pgsizes_only - Limit page-sizes used for v1 page-tables
+                                         to 4KiB/2Mib/1GiB.
+
 
        amd_iommu_dump= [HW,X86-64]
                        Enable AMD IOMMU driver option to dump the ACPI table
                        Format: <io>,<irq>,<mode>
                        See header of drivers/net/hamradio/baycom_ser_hdx.c.
 
+       bdev_allow_write_mounted=
+                       Format: <bool>
+                       Control the ability to open a mounted block device
+                       for writing, i.e., allow / disallow writes that bypass
+                       the FS. This was implemented as a means to prevent
+                       fuzzers from crashing the kernel by overwriting the
+                       metadata underneath a mounted FS without its awareness.
+                       This also prevents destructive formatting of mounted
+                       filesystems by naive storage tooling that don't use
+                       O_EXCL. Default is Y and can be changed through the
+                       Kconfig option CONFIG_BLK_DEV_WRITE_MOUNTED.
+
        bert_disable    [ACPI]
                        Disable BERT OS support on buggy BIOSes.
 
        ipcmni_extend   [KNL,EARLY] Extend the maximum number of unique System V
                        IPC identifiers from 32,768 to 16,777,216.
 
+       ipe.enforce=    [IPE]
+                       Format: <bool>
+                       Determine whether IPE starts in permissive (0) or
+                       enforce (1) mode. The default is enforce.
+
+       ipe.success_audit=
+                       [IPE]
+                       Format: <bool>
+                       Start IPE with success auditing enabled, emitting
+                       an audit event when a binary is allowed. The default
+                       is 0.
+
        irqaffinity=    [SMP] Set the default irq affinity mask
                        The argument is a cpu list, as described above.
 
                        Disable NUMA, Only set up a single NUMA node
                        spanning all memory.
 
+       numa=fake=<size>[MG]
+                       [KNL, ARM64, RISCV, X86, EARLY]
+                       If given as a memory unit, fills all system RAM with
+                       nodes of size interleaved over physical nodes.
+
+       numa=fake=<N>
+                       [KNL, ARM64, RISCV, X86, EARLY]
+                       If given as an integer, fills all system RAM with N
+                       fake nodes interleaved over physical nodes.
+
+       numa=fake=<N>U
+                       [KNL, ARM64, RISCV, X86, EARLY]
+                       If given as an integer followed by 'U', it will
+                       divide each physical node into N emulated nodes.
+
        numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
                        NUMA balancing.
                        Allowed values are enable and disable
        printk.time=    Show timing data prefixed to each printk message line
                        Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
 
+       proc_mem.force_override= [KNL]
+                       Format: {always | ptrace | never}
+                       Traditionally /proc/pid/mem allows memory permissions to be
+                       overridden without restrictions. This option may be set to
+                       restrict that. Can be one of:
+                       - 'always': traditional behavior always allows mem overrides.
+                       - 'ptrace': only allow mem overrides for active ptracers.
+                       - 'never':  never allow mem overrides.
+                       If not specified, default is the CONFIG_PROC_MEM_* choice.
+
        processor.max_cstate=   [HW,ACPI]
                        Limit processor to maximum C-state
                        max_cstate=9 overrides any DMI blacklist limit.
                        Set maximum number of finished RCU callbacks to
                        process in one batch.
 
+       rcutree.csd_lock_suppress_rcu_stall=    [KNL]
+                       Do only a one-line RCU CPU stall warning when
+                       there is an ongoing too-long CSD-lock wait.
+
        rcutree.do_rcu_barrier= [KNL]
                        Request a call to rcu_barrier().  This is
                        throttled so that userspace tests can safely
                        Time to wait (s) after boot before inducing stall.
 
        rcutorture.stall_cpu_irqsoff= [KNL]
-                       Disable interrupts while stalling if set.
+                       Disable interrupts while stalling if set, but only
+                       on the first stall in the set.
+
+       rcutorture.stall_cpu_repeat= [KNL]
+                       Number of times to repeat the stall sequence,
+                       so that rcutorture.stall_cpu_repeat=3 will result
+                       in four stall sequences.
 
        rcutorture.stall_gp_kthread= [KNL]
                        Duration (s) of forced sleep within RCU
                        of zero will disable batching.  Batching is
                        always disabled for synchronize_rcu_tasks().
 
-       rcupdate.rcu_tasks_rude_lazy_ms= [KNL]
-                       Set timeout in milliseconds RCU Tasks
-                       Rude asynchronous callback batching for
-                       call_rcu_tasks_rude().  A negative value
-                       will take the default.  A value of zero will
-                       disable batching.  Batching is always disabled
-                       for synchronize_rcu_tasks_rude().
-
        rcupdate.rcu_tasks_trace_lazy_ms= [KNL]
                        Set timeout in milliseconds RCU Tasks
                        Trace asynchronous callback batching for
                        <deci-seconds>: poll all this frequency
                        0: no polling (default)
 
+       thp_anon=       [KNL]
+                       Format: <size>,<size>[KMG]:<state>;<size>-<size>[KMG]:<state>
+                       state is one of "always", "madvise", "never" or "inherit".
+                       Control the default behavior of the system with respect
+                       to anonymous transparent hugepages.
+                       Can be used multiple times for multiple anon THP sizes.
+                       See Documentation/admin-guide/mm/transhuge.rst for more
+                       details.
+
        threadirqs      [KNL,EARLY]
                        Force threading of all interrupt handlers except those
                        marked explicitly IRQF_NO_THREAD.
                        it can be updated at runtime by writing to the
                        corresponding sysfs file.
 
+       workqueue.panic_on_stall=<uint>
+                       Panic when workqueue stall is detected by
+                       CONFIG_WQ_WATCHDOG. It sets the number times of the
+                       stall to trigger panic.
+
+                       The default is 0, which disables the panic on stall.
+
        workqueue.cpu_intensive_thresh_us=
                        Per-cpu work items which run for longer than this
                        threshold are automatically considered CPU intensive
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