the GPE dispatcher.
This facility can be used to prevent such uncontrolled
GPE floodings.
- Format: <byte>
+ Format: <byte> or <bitmap-list>
acpi_no_auto_serialize [HW,ACPI]
Disable auto-serialization of AML methods
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.
amd_iommu_dump= [HW,X86-64]
Enable AMD IOMMU driver option to dump the ACPI table
ccw_timeout_log [S390]
See Documentation/s390/common_io.rst for details.
- cgroup_disable= [KNL] Disable a particular controller
- Format: {name of the controller(s) to disable}
+ cgroup_disable= [KNL] Disable a particular controller or optional feature
+ Format: {name of the controller(s) or feature(s) to disable}
The effects of cgroup_disable=foo are:
- foo isn't auto-mounted if you mount all cgroups in
a single hierarchy
- foo isn't visible as an individually mountable
subsystem
+ - if foo is an optional feature then the feature is
+ disabled and corresponding cgroup files are not
+ created
{Currently only "memory" controller deal with this and
cut the overhead, others just disable the usage. So
only cgroup_disable=memory is actually worthy}
+ Specifying "pressure" disables per-cgroup pressure
+ stall information accounting feature
cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
Format: { { controller | "all" | "named" }
loops can be debugged more effectively on production
systems.
+ clocksource.max_cswd_read_retries= [KNL]
+ Number of clocksource_watchdog() retries due to
+ external delays before the clock will be marked
+ unstable. Defaults to three retries, that is,
+ four attempts to read the clock under test.
+
+ clocksource.verify_n_cpus= [KNL]
+ Limit the number of CPUs checked for clocksources
+ marked with CLOCK_SOURCE_VERIFY_PERCPU that
+ are marked unstable due to excessive skew.
+ A negative value says to check all CPUs, while
+ zero says not to check any. Values larger than
+ nr_cpu_ids are silently truncated to nr_cpu_ids.
+ The actual CPUs are chosen randomly, with
+ no replacement if the same CPU is chosen twice.
+
+ clocksource-wdtest.holdoff= [KNL]
+ Set the time in seconds that the clocksource
+ watchdog test waits before commencing its tests.
+ Defaults to zero when built as a module and to
+ 10 seconds when built into the kernel.
+
clearcpuid=BITNUM[,BITNUM...] [X86]
Disable CPUID feature X for the kernel. See
arch/x86/include/asm/cpufeatures.h for the valid bit
Documentation/admin-guide/mm/hugetlbpage.rst.
Format: size[KMG]
+ hugetlb_free_vmemmap=
+ [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+ enabled.
+ Allows heavy hugetlb users to free up some more
+ memory (6 * PAGE_SIZE for each 2MB hugetlb page).
+ Format: { on | off (default) }
+
+ on: enable the feature
+ off: disable the feature
+
+ Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y,
+ the default is on.
+
+ This is not compatible with memory_hotplug.memmap_on_memory.
+ If both parameters are enabled, hugetlb_free_vmemmap takes
+ precedence over memory_hotplug.memmap_on_memory.
+
hung_task_panic=
[KNL] Should the hung task detector generate panics.
Format: 0 | 1
forcing Dual Address Cycle for PCI cards supporting
greater than 32-bit addressing.
- iommu.strict= [ARM64] Configure TLB invalidation behaviour
+ iommu.strict= [ARM64, X86] Configure TLB invalidation behaviour
Format: { "0" | "1" }
0 - Lazy mode.
Request that DMA unmap operations use deferred
1 - Strict mode (default).
DMA unmap operations invalidate IOMMU hardware TLBs
synchronously.
+ Note: on x86, the default behaviour depends on the
+ equivalent driver-specific parameters, but a strict
+ mode explicitly specified by either method takes
+ precedence.
iommu.passthrough=
[ARM64, X86] Configure DMA to bypass the IOMMU by default.
Note that even when enabled, there are a few cases where
the feature is not effective.
+ This is not compatible with hugetlb_free_vmemmap. If
+ both parameters are enabled, hugetlb_free_vmemmap takes
+ precedence over memory_hotplug.memmap_on_memory.
+
memtest= [KNL,X86,ARM,PPC,RISCV] Enable memtest
Format: <integer>
default : 0 <disable>
noclflush [BUGS=X86] Don't use the CLFLUSH instruction
- nodelayacct [KNL] Disable per-task delay accounting
+ delayacct [KNL] Enable per-task delay accounting
nodsp [SH] Disable hardware DSP at boot time.
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
+ numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
+ set up a single NUMA node spanning all memory.
+
numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
NUMA balancing.
Allowed values are enable and disable
off: turn off poisoning (default)
on: turn on poisoning
+ page_reporting.page_reporting_order=
+ [KNL] Minimal page reporting order
+ Format: <integer>
+ Adjust the minimal page reporting order. The page
+ reporting is disabled when it exceeds (MAX_ORDER-1).
+
panic= [KNL] Kernel behaviour on panic: delay <timeout>
timeout > 0: seconds before rebooting
timeout = 0: wait forever
Reserves a hole at the top of the kernel virtual
address space.
- reservelow= [X86]
- Format: nn[K]
- Set the amount of memory to reserve for BIOS at
- the bottom of the address space.
-
reset_devices [KNL] Force drivers to reset the underlying device
during initialization.
exception. Default behavior is by #AC if
both features are enabled in hardware.
+ ratelimit:N -
+ Set system wide rate limit to N bus locks
+ per second for bus lock detection.
+ 0 < N <= 1000.
+
+ N/A for split lock detection.
+
+
If an #AC exception is hit in the kernel or in
firmware (i.e. not while executing in user mode)
the kernel will oops in either "warn" or "fatal"
Note, echoing 1 into this file without the
tracepoint_printk kernel cmdline option has no effect.
+ The tp_printk_stop_on_boot (see below) can also be used
+ to stop the printing of events to console at
+ late_initcall_sync.
+
** CAUTION **
Having tracepoints sent to printk() and activating high
frequency tracepoints such as irq or sched, can cause
the system to live lock.
+ tp_printk_stop_on_boot[FTRACE]
+ When tp_printk (above) is set, it can cause a lot of noise
+ on the console. It may be useful to only include the
+ printing of events during boot up, as user space may
+ make the system inoperable.
+
+ This command line option will stop the printing of events
+ to console at the late_initcall_sync() time frame.
+
traceoff_on_warning
[FTRACE] enable this option to disable tracing when a
warning is hit. This turns off "tracing_on". Tracing can
projects / linux-2.6-microblaze.git / blobdiff