cpufreq.off=1 [CPU_FREQ]
disable the cpufreq sub-system
+ cpufreq.default_governor=
+ [CPU_FREQ] Name of the default cpufreq governor or
+ policy to use. This governor must be registered in the
+ kernel before the cpufreq driver probes.
+
cpu_init_udelay=N
[X86] Delay for N microsec between assert and de-assert
of APIC INIT to start processors. This delay occurs
memory region [offset, offset + size] for that kernel
image. If '@offset' is omitted, then a suitable offset
is selected automatically.
- [KNL, x86_64] select a region under 4G first, and
+ [KNL, X86-64] Select a region under 4G first, and
fall back to reserve region above 4G when '@offset'
hasn't been specified.
See Documentation/admin-guide/kdump/kdump.rst for further details.
Documentation/admin-guide/kdump/kdump.rst for an example.
crashkernel=size[KMG],high
- [KNL, x86_64] range could be above 4G. Allow kernel
+ [KNL, X86-64] range could be above 4G. Allow kernel
to allocate physical memory region from top, so could
be above 4G if system have more than 4G ram installed.
Otherwise memory region will be allocated below 4G, if
available.
It will be ignored if crashkernel=X is specified.
crashkernel=size[KMG],low
- [KNL, x86_64] range under 4G. When crashkernel=X,high
+ [KNL, X86-64] range under 4G. When crashkernel=X,high
is passed, kernel could allocate physical memory region
above 4G, that cause second kernel crash on system
that require some amount of low memory, e.g. swiotlb
useful to also enable the page_owner functionality.
on: enable the feature
+ debugfs= [KNL] This parameter enables what is exposed to userspace
+ and debugfs internal clients.
+ Format: { on, no-mount, off }
+ on: All functions are enabled.
+ no-mount:
+ Filesystem is not registered but kernel clients can
+ access APIs and a crashkernel can be used to read
+ its content. There is nothing to mount.
+ off: Filesystem is not registered and clients
+ get a -EPERM as result when trying to register files
+ or directories within debugfs.
+ This is equivalent of the runtime functionality if
+ debugfs was not enabled in the kernel at all.
+ Default value is set in build-time with a kernel configuration.
+
debugpat [X86] Enable PAT debugging
decnet.addr= [HW,NET]
disable_radix [PPC]
Disable RADIX MMU mode on POWER9
+ radix_hcall_invalidate=on [PPC/PSERIES]
+ Disable RADIX GTSE feature and use hcall for TLB
+ invalidate.
+
disable_tlbie [PPC]
Disable TLBIE instruction. Currently does not work
with KVM, with HASH MMU, or with coherent accelerators.
gamma= [HW,DRM]
- gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
+ gart_fix_e820= [X86-64] disable the fix e820 for K8 GART
Format: off | on
default: on
Format: 0 | 1
Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.
- init_pkru= [x86] Specify the default memory protection keys rights
+ init_pkru= [X86] Specify the default memory protection keys rights
register contents for all processes. 0x55555554 by
default (disallow access to all but pkey 0). Can
override in debugfs after boot.
inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
Format: <irq>
- int_pln_enable [x86] Enable power limit notification interrupt
+ int_pln_enable [X86] Enable power limit notification interrupt
integrity_audit=[IMA]
Format: { "0" | "1" }
bypassed by not enabling DMAR with this option. In
this case, gfx device will use physical address for
DMA.
- forcedac [x86_64]
+ forcedac [X86-64]
With this option iommu will not optimize to look
for io virtual address below 32-bit forcing dual
address cycle on pci bus for cards supporting greater
strict regions from userspace.
relaxed
- iommu= [x86]
+ iommu= [X86]
off
force
noforce
merge
nomerge
soft
- pt [x86]
- nopt [x86]
+ pt [X86]
+ nopt [X86]
nobypass [PPC/POWERNV]
Disable IOMMU bypass, using IOMMU for PCI devices.
iucv= [HW,NET]
- ivrs_ioapic [HW,X86_64]
+ ivrs_ioapic [HW,X86-64]
Provide an override to the IOAPIC-ID<->DEVICE-ID
mapping provided in the IVRS ACPI table. For
example, to map IOAPIC-ID decimal 10 to
PCI device 00:14.0 write the parameter as:
ivrs_ioapic[10]=00:14.0
- ivrs_hpet [HW,X86_64]
+ ivrs_hpet [HW,X86-64]
Provide an override to the HPET-ID<->DEVICE-ID
mapping provided in the IVRS ACPI table. For
example, to map HPET-ID decimal 0 to
PCI device 00:14.0 write the parameter as:
ivrs_hpet[0]=00:14.0
- ivrs_acpihid [HW,X86_64]
+ ivrs_acpihid [HW,X86-64]
Provide an override to the ACPI-HID:UID<->DEVICE-ID
mapping provided in the IVRS ACPI table. For
example, to map UART-HID:UID AMD0020:0 to
lapic [X86-32,APIC] Enable the local APIC even if BIOS
disabled it.
- lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
+ lapic= [X86,APIC] "notscdeadline" Do not use TSC deadline
value for LAPIC timer one-shot implementation. Default
back to the programmable timer unit in the LAPIC.
no5lvl [X86-64] Disable 5-level paging mode. Forces
kernel to use 4-level paging instead.
+ nofsgsbase [X86] Disables FSGSBASE instructions.
+
no_console_suspend
[HW] Never suspend the console
Disable suspending of consoles during suspend and
register save and restore. The kernel will only save
legacy floating-point registers on task switch.
- nohugeiomap [KNL,x86,PPC] Disable kernel huge I/O mappings.
+ nohugeiomap [KNL,X86,PPC] Disable kernel huge I/O mappings.
nosmt [KNL,S390] Disable symmetric multithreading (SMT).
Equivalent to smt=1.
- [KNL,x86] Disable symmetric multithreading (SMT).
+ [KNL,X86] Disable symmetric multithreading (SMT).
nosmt=force: Force disable SMT, cannot be undone
via the sysfs control file.
pt. [PARIDE]
See Documentation/admin-guide/blockdev/paride.rst.
- pti= [X86_64] Control Page Table Isolation of user and
+ pti= [X86-64] Control Page Table Isolation of user and
kernel address spaces. Disabling this feature
removes hardening, but improves performance of
system calls and interrupts.
Not specifying this option is equivalent to pti=auto.
- nopti [X86_64]
+ nopti [X86-64]
Equivalent to pti=off
pty.legacy_count=
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.jiffies_till_first_fqs= [KNL]
Set delay from grace-period initialization to
first attempt to force quiescent states.
Set time (jiffies) between CPU-hotplug operations,
or zero to disable CPU-hotplug testing.
+ rcutorture.read_exit= [KNL]
+ Set the number of read-then-exit kthreads used
+ to test the interaction of RCU updaters and
+ task-exit processing.
+
+ rcutorture.read_exit_burst= [KNL]
+ The number of times in a given read-then-exit
+ episode that a set of read-then-exit kthreads
+ is spawned.
+
+ rcutorture.read_exit_delay= [KNL]
+ The delay, in seconds, between successive
+ read-then-exit testing episodes.
+
rcutorture.shuffle_interval= [KNL]
Set task-shuffle interval (s). Shuffling tasks
allows some CPUs to go into dyntick-idle mode
reboot_cpu is s[mp]#### with #### being the processor
to be used for rebooting.
+ refscale.holdoff= [KNL]
+ Set test-start holdoff period. The purpose of
+ this parameter is to delay the start of the
+ test until boot completes in order to avoid
+ interference.
+
+ refscale.loops= [KNL]
+ Set the number of loops over the synchronization
+ primitive under test. Increasing this number
+ reduces noise due to loop start/end overhead,
+ but the default has already reduced the per-pass
+ noise to a handful of picoseconds on ca. 2020
+ x86 laptops.
+
+ refscale.nreaders= [KNL]
+ Set number of readers. The default value of -1
+ selects N, where N is roughly 75% of the number
+ of CPUs. A value of zero is an interesting choice.
+
+ refscale.nruns= [KNL]
+ Set number of runs, each of which is dumped onto
+ the console log.
+
+ refscale.readdelay= [KNL]
+ Set the read-side critical-section duration,
+ measured in microseconds.
+
+ refscale.scale_type= [KNL]
+ Specify the read-protection implementation to test.
+
+ refscale.shutdown= [KNL]
+ Shut down the system at the end of the performance
+ test. This defaults to 1 (shut it down) when
+ rcuperf is built into the kernel and to 0 (leave
+ it running) when rcuperf is built as a module.
+
+ refscale.verbose= [KNL]
+ Enable additional printk() statements.
+
relax_domain_level=
[KNL, SMP] Set scheduler's default relax_domain_level.
See Documentation/admin-guide/cgroup-v1/cpusets.rst.
fragmentation. Defaults to 1 for systems with
more than 32MB of RAM, 0 otherwise.
- slub_debug[=options[,slabs]] [MM, SLUB]
+ slub_debug[=options[,slabs][;[options[,slabs]]...] [MM, SLUB]
Enabling slub_debug allows one to determine the
culprit if slab objects become corrupted. Enabling
slub_debug can create guard zones around objects and
Prevent the CPU-hotplug component of torturing
until after init has spawned.
+ torture.ftrace_dump_at_shutdown= [KNL]
+ Dump the ftrace buffer at torture-test shutdown,
+ even if there were no errors. This can be a
+ very costly operation when many torture tests
+ are running concurrently, especially on systems
+ with rotating-rust storage.
+
tp720= [HW,PS2]
tpm_suspend_pcr=[HW,TPM]
panic() code such as dumping handler.
xen_nopvspin [X86,XEN]
- Disables the ticketlock slowpath using Xen PV
- optimizations.
+ Disables the qspinlock slowpath using Xen PV optimizations.
+ This parameter is obsoleted by "nopvspin" parameter, which
+ has equivalent effect for XEN platform.
xen_nopv [X86]
Disables the PV optimizations forcing the HVM guest to
as generic guest with no PV drivers. Currently support
XEN HVM, KVM, HYPER_V and VMWARE guest.
+ nopvspin [X86,XEN,KVM]
+ Disables the qspinlock slow path using PV optimizations
+ which allow the hypervisor to 'idle' the guest on lock
+ contention.
+
xirc2ps_cs= [NET,PCMCIA]
Format:
<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
cdrom_release, /∗ release ∗/
NULL, /∗ fsync ∗/
NULL, /∗ fasync ∗/
- cdrom_media_changed, /∗ media change ∗/
NULL /∗ revalidate ∗/
};
CDS_DRIVE_NOT_READY /* something is wrong, tray is moving? */
CDS_DISC_OK /* a disc is loaded and everything is fine */
-::
-
- int media_changed(struct cdrom_device_info *cdi, int disc_nr)
-
-This function is very similar to the original function in $struct
-file_operations*. It returns 1 if the medium of the device *cdi->dev*
-has changed since the last call, and 0 otherwise. The parameter
-*disc_nr* identifies a specific slot in a juke-box, it should be
-ignored for single-disc drives. Note that by `re-routing` this
-function through *cdrom_media_changed()*, we can implement separate
-queues for the VFS and a new *ioctl()* function that can report device
-changes to software (e. g., an auto-mounting daemon).
-
::
int tray_move(struct cdrom_device_info *cdi, int position)
CDC_DRIVE_STATUS /* driver implements drive status */
The capability flag is declared *const*, to prevent drivers from
- accidentally tampering with the contents. The capability fags actually
+ accidentally tampering with the contents. The capability flags actually
inform `cdrom.c` of what the driver can do. If the drive found
by the driver does not have the capability, is can be masked out by
the *cdrom_device_info* variable *mask*. For instance, the SCSI CD-ROM
Only a few routines in `cdrom.c` are exported to the drivers. In this
new section we will discuss these, as well as the functions that `take
- over' the CD-ROM interface to the kernel. The header file belonging
+ over` the CD-ROM interface to the kernel. The header file belonging
to `cdrom.c` is called `cdrom.h`. Formerly, some of the contents of this
file were placed in the file `ucdrom.h`, but this file has now been
merged back into `cdrom.h`.
maximum number of discs in the juke-box found in the *cdrom_dops*.
`CDROM_MEDIA_CHANGED`
Returns 1 if a disc has been changed since the last call.
- Note that calls to *cdrom_media_changed* by the VFS are treated
- by an independent queue, so both mechanisms will detect a
- media change once. For juke-boxes, an extra argument *arg*
+ For juke-boxes, an extra argument *arg*
specifies the slot for which the information is given. The special
value *CDSL_CURRENT* requests that information about the currently
selected slot be returned.
projects / mirror_ubuntu-jammy-kernel.git / commitdiff