- acpi= [HW,ACPI,X86,ARM64]
+ acpi= [HW,ACPI,X86,ARM64,RISCV64]
Advanced Configuration and Power Interface
Format: { force | on | off | strict | noirq | rsdt |
copy_dsdt }
force -- enable ACPI if default was off
- on -- enable ACPI but allow fallback to DT [arm64]
+ on -- enable ACPI but allow fallback to DT [arm64,riscv64]
off -- disable ACPI if default was on
noirq -- do not use ACPI for IRQ routing
strict -- Be less tolerant of platforms that are not
strictly ACPI specification compliant.
rsdt -- prefer RSDT over (default) XSDT
copy_dsdt -- copy DSDT to memory
- For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force"
- are available
+ For ARM64 and RISCV64, ONLY "acpi=off", "acpi=on" or
+ "acpi=force" are available
See also Documentation/power/runtime_pm.rst, pci=noacpi
EL0 is indicated by /sys/devices/system/cpu/aarch32_el0
and hot-unplug operations may be restricted.
- See Documentation/arm64/asymmetric-32bit.rst for more
+ See Documentation/arch/arm64/asymmetric-32bit.rst for more
information.
amd_iommu= [HW,X86-64]
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.
amd_iommu_dump= [HW,X86-64]
Enable AMD IOMMU driver option to dump the ACPI table
arm64.nosme [ARM64] Unconditionally disable Scalable Matrix
Extension support
+ arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory
+ Set instructions support
+
ataflop= [HW,M68k]
atarimouse= [HW,MOUSE] Atari Mouse
Format:
<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
- cpu0_hotplug [X86] Turn on CPU0 hotplug feature when
- CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
- Some features depend on CPU0. Known dependencies are:
- 1. Resume from suspend/hibernate depends on CPU0.
- Suspend/hibernate will fail if CPU0 is offline and you
- need to online CPU0 before suspend/hibernate.
- 2. PIC interrupts also depend on CPU0. CPU0 can't be
- removed if a PIC interrupt is detected.
- It's said poweroff/reboot may depend on CPU0 on some
- machines although I haven't seen such issues so far
- after CPU0 is offline on a few tested machines.
- If the dependencies are under your control, you can
- turn on cpu0_hotplug.
-
cpuidle.off=1 [CPU_IDLE]
disable the cpuidle sub-system
on every CPU online, such as boot, and resume from suspend.
Default: 10000
+ cpuhp.parallel=
+ [SMP] Enable/disable parallel bringup of secondary CPUs
+ Format: <bool>
+ Default is enabled if CONFIG_HOTPLUG_PARALLEL=y. Otherwise
+ the parameter has no effect.
+
crash_kexec_post_notifiers
Run kdump after running panic-notifiers and dumping
kmsg. This only for the users who doubt kdump always
[HW] Make the MicroTouch USB driver use raw coordinates
('y', default) or cooked coordinates ('n')
+ mtrr=debug [X86]
+ Enable printing debug information related to MTRR
+ registers at boot time.
+
mtrr_chunk_size=nn[KMG] [X86]
used for mtrr cleanup. It is largest continuous chunk
that could hold holes aka. UC entries.
nohibernate [HIBERNATION] Disable hibernation and resume.
- nohlt [ARM,ARM64,MICROBLAZE,SH] Forces the kernel to busy wait
- in do_idle() and not use the arch_cpu_idle()
+ nohlt [ARM,ARM64,MICROBLAZE,MIPS,SH] Forces the kernel to
+ busy wait in do_idle() and not use the arch_cpu_idle()
implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP
to be effective. This is useful on platforms where the
sleep(SH) or wfi(ARM,ARM64) instructions do not work
nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
and disable the IO APIC. legacy for "maxcpus=0".
- nosmt [KNL,S390] Disable symmetric multithreading (SMT).
+ nosmt [KNL,MIPS,S390] Disable symmetric multithreading (SMT).
Equivalent to smt=1.
[KNL,X86] Disable symmetric multithreading (SMT).
the propagation of recent CPU-hotplug changes up
the rcu_node combining tree.
- rcutree.use_softirq= [KNL]
- If set to zero, move all RCU_SOFTIRQ processing to
- per-CPU rcuc kthreads. Defaults to a non-zero
- value, meaning that RCU_SOFTIRQ is used by default.
- Specify rcutree.use_softirq=0 to use rcuc kthreads.
-
- But note that CONFIG_PREEMPT_RT=y kernels disable
- this kernel boot parameter, forcibly setting it
- to zero.
-
- rcutree.rcu_fanout_exact= [KNL]
- Disable autobalancing of the rcu_node combining
- tree. This is used by rcutorture, and might
- possibly be useful for architectures having high
- cache-to-cache transfer latencies.
-
- rcutree.rcu_fanout_leaf= [KNL]
- Change the number of CPUs assigned to each
- leaf rcu_node structure. Useful for very
- large systems, which will choose the value 64,
- and for NUMA systems with large remote-access
- latencies, which will choose a value aligned
- with the appropriate hardware boundaries.
-
- rcutree.rcu_min_cached_objs= [KNL]
- Minimum number of objects which are cached and
- maintained per one CPU. Object size is equal
- to PAGE_SIZE. The cache allows to reduce the
- pressure to page allocator, also it makes the
- whole algorithm to behave better in low memory
- condition.
-
- rcutree.rcu_delay_page_cache_fill_msec= [KNL]
- Set the page-cache refill delay (in milliseconds)
- in response to low-memory conditions. The range
- of permitted values is in the range 0:100000.
-
rcutree.jiffies_till_first_fqs= [KNL]
Set delay from grace-period initialization to
first attempt to force quiescent states.
When RCU_NOCB_CPU is set, also adjust the
priority of NOCB callback kthreads.
- rcutree.rcu_divisor= [KNL]
- Set the shift-right count to use to compute
- the callback-invocation batch limit bl from
- the number of callbacks queued on this CPU.
- The result will be bounded below by the value of
- the rcutree.blimit kernel parameter. Every bl
- callbacks, the softirq handler will exit in
- order to allow the CPU to do other work.
-
- Please note that this callback-invocation batch
- limit applies only to non-offloaded callback
- invocation. Offloaded callbacks are instead
- invoked in the context of an rcuoc kthread, which
- scheduler will preempt as it does any other task.
-
rcutree.nocb_nobypass_lim_per_jiffy= [KNL]
On callback-offloaded (rcu_nocbs) CPUs,
RCU reduces the lock contention that would
the ->nocb_bypass queue. The definition of "too
many" is supplied by this kernel boot parameter.
- rcutree.rcu_nocb_gp_stride= [KNL]
- Set the number of NOCB callback kthreads in
- each group, which defaults to the square root
- of the number of CPUs. Larger numbers reduce
- the wakeup overhead on the global grace-period
- kthread, but increases that same overhead on
- each group's NOCB grace-period kthread.
-
rcutree.qhimark= [KNL]
Set threshold of queued RCU callbacks beyond which
batch limiting is disabled.
on rcutree.qhimark at boot time and to zero to
disable more aggressive help enlistment.
+ rcutree.rcu_delay_page_cache_fill_msec= [KNL]
+ Set the page-cache refill delay (in milliseconds)
+ in response to low-memory conditions. The range
+ of permitted values is in the range 0:100000.
+
+ rcutree.rcu_divisor= [KNL]
+ Set the shift-right count to use to compute
+ the callback-invocation batch limit bl from
+ the number of callbacks queued on this CPU.
+ The result will be bounded below by the value of
+ the rcutree.blimit kernel parameter. Every bl
+ callbacks, the softirq handler will exit in
+ order to allow the CPU to do other work.
+
+ Please note that this callback-invocation batch
+ limit applies only to non-offloaded callback
+ invocation. Offloaded callbacks are instead
+ invoked in the context of an rcuoc kthread, which
+ scheduler will preempt as it does any other task.
+
+ rcutree.rcu_fanout_exact= [KNL]
+ Disable autobalancing of the rcu_node combining
+ tree. This is used by rcutorture, and might
+ possibly be useful for architectures having high
+ cache-to-cache transfer latencies.
+
+ rcutree.rcu_fanout_leaf= [KNL]
+ Change the number of CPUs assigned to each
+ leaf rcu_node structure. Useful for very
+ large systems, which will choose the value 64,
+ and for NUMA systems with large remote-access
+ latencies, which will choose a value aligned
+ with the appropriate hardware boundaries.
+
+ rcutree.rcu_min_cached_objs= [KNL]
+ Minimum number of objects which are cached and
+ maintained per one CPU. Object size is equal
+ to PAGE_SIZE. The cache allows to reduce the
+ pressure to page allocator, also it makes the
+ whole algorithm to behave better in low memory
+ condition.
+
+ rcutree.rcu_nocb_gp_stride= [KNL]
+ Set the number of NOCB callback kthreads in
+ each group, which defaults to the square root
+ of the number of CPUs. Larger numbers reduce
+ the wakeup overhead on the global grace-period
+ kthread, but increases that same overhead on
+ each group's NOCB grace-period kthread.
+
rcutree.rcu_kick_kthreads= [KNL]
Cause the grace-period kthread to get an extra
wake_up() if it sleeps three times longer than
This wake_up() will be accompanied by a
WARN_ONCE() splat and an ftrace_dump().
+ rcutree.rcu_resched_ns= [KNL]
+ Limit the time spend invoking a batch of RCU
+ callbacks to the specified number of nanoseconds.
+ By default, this limit is checked only once
+ every 32 callbacks in order to limit the pain
+ inflicted by local_clock() overhead.
+
rcutree.rcu_unlock_delay= [KNL]
In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
this specifies an rcu_read_unlock()-time delay
rcu_node tree with an eye towards determining
why a new grace period has not yet started.
+ rcutree.use_softirq= [KNL]
+ If set to zero, move all RCU_SOFTIRQ processing to
+ per-CPU rcuc kthreads. Defaults to a non-zero
+ value, meaning that RCU_SOFTIRQ is used by default.
+ Specify rcutree.use_softirq=0 to use rcuc kthreads.
+
+ But note that CONFIG_PREEMPT_RT=y kernels disable
+ this kernel boot parameter, forcibly setting it
+ to zero.
+
rcuscale.gp_async= [KNL]
Measure performance of asynchronous
grace-period primitives such as call_rcu().
rcutorture.stall_cpu_block= [KNL]
Sleep while stalling if set. This will result
- in warnings from preemptible RCU in addition
- to any other stall-related activity.
+ in warnings from preemptible RCU in addition to
+ any other stall-related activity. Note that
+ in kernels built with CONFIG_PREEMPTION=n and
+ CONFIG_PREEMPT_COUNT=y, this parameter will
+ cause the CPU to pass through a quiescent state.
+ Given CONFIG_PREEMPTION=n, this will suppress
+ RCU CPU stall warnings, but will instead result
+ in scheduling-while-atomic splats.
+
+ Use of this module parameter results in splats.
+
rcutorture.stall_cpu_holdoff= [KNL]
Time to wait (s) after boot before inducing stall.
port and the regular usb controller gets disabled.
root= [KNL] Root filesystem
- See name_to_dev_t comment in init/do_mounts.c.
+ Usually this a a block device specifier of some kind,
+ see the early_lookup_bdev comment in
+ block/early-lookup.c for details.
+ Alternatively this can be "ram" for the legacy initial
+ ramdisk, "nfs" and "cifs" for root on a network file
+ system, or "mtd" and "ubi" for mounting from raw flash.
rootdelay= [KNL] Delay (in seconds) to pause before attempting to
mount the root filesystem
1: Fast pin select (default)
2: ATC IRMode
- smt= [KNL,S390] Set the maximum number of threads (logical
+ smt= [KNL,MIPS,S390] Set the maximum number of threads (logical
CPUs) to use per physical CPU on systems capable of
symmetric multithreading (SMT). Will be capped to the
actual hardware limit.
unknown_nmi_panic
[X86] Cause panic on unknown NMI.
+ unwind_debug [X86-64]
+ Enable unwinder debug output. This can be
+ useful for debugging certain unwinder error
+ conditions, including corrupt stacks and
+ bad/missing unwinder metadata.
+
usbcore.authorized_default=
[USB] Default USB device authorization:
(default -1 = authorized except for wireless USB,
it can be updated at runtime by writing to the
corresponding sysfs file.
+ workqueue.cpu_intensive_thresh_us=
+ Per-cpu work items which run for longer than this
+ threshold are automatically considered CPU intensive
+ and excluded from concurrency management to prevent
+ them from noticeably delaying other per-cpu work
+ items. Default is 10000 (10ms).
+
+ If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel
+ will report the work functions which violate this
+ threshold repeatedly. They are likely good
+ candidates for using WQ_UNBOUND workqueues instead.
+
workqueue.disable_numa
By default, all work items queued to unbound
workqueues are affine to the NUMA nodes they're
projects / platform / kernel / linux-rpi.git / blobdiff