This facility can be used to prevent such uncontrolled
GPE floodings.
Format: <int>
- Support masking of GPEs numbered from 0x00 to 0x7f.
acpi_no_auto_serialize [HW,ACPI]
Disable auto-serialization of AML methods
acpi_sleep= [HW,ACPI] Sleep options
Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
- old_ordering, nonvs, sci_force_enable }
+ old_ordering, nonvs, sci_force_enable, nobl }
See Documentation/power/video.txt for information on
s3_bios and s3_mode.
s3_beep is for debugging; it makes the PC's speaker beep
sci_force_enable causes the kernel to set SCI_EN directly
on resume from S1/S3 (which is against the ACPI spec,
but some broken systems don't work without it).
+ nobl causes the internal blacklist of systems known to
+ behave incorrectly in some ways with respect to system
+ suspend and resume to be ignored (use wisely).
acpi_use_timer_override [HW,ACPI]
Use timer override. For some broken Nvidia NF5 boards
not play well with APC CPU idle - disable it if you have
APC and your system crashes randomly.
- apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
+ apic= [APIC,X86] Advanced Programmable Interrupt Controller
Change the output verbosity whilst booting
Format: { quiet (default) | verbose | debug }
Change the amount of debugging information output
when initialising the APIC and IO-APIC components.
+ For X86-32, this can also be used to specify an APIC
+ driver name.
+ Format: apic=driver_name
+ Examples: apic=bigsmp
apic_extnmi= [APIC,X86] External NMI delivery setting
Format: { bsp (default) | all | none }
It will be ignored when crashkernel=X,high is not used
or memory reserved is below 4G.
- crossrelease_fullstack
- [KNL] Allow to record full stack trace in cross-release
-
cryptomgr.notests
[KNL] Disable crypto self-tests
isapnp= [ISAPNP]
Format: <RDP>,<reset>,<pci_scan>,<verbosity>
- isolcpus= [KNL,SMP] Isolate a given set of CPUs from disturbance.
+ isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
[Deprecated - use cpusets instead]
Format: [flag-list,]<cpu-list>
[KVM,ARM] Trap guest accesses to GICv3 common
system registers
+ kvm-arm.vgic_v4_enable=
+ [KVM,ARM] Allow use of GICv4 for direct injection of
+ LPIs.
+
kvm-intel.ept= [KVM,Intel] Disable extended page tables
(virtualized MMU) support on capable Intel chips.
Default is 1 (enabled)
This tests the locking primitive's ability to
transition abruptly to and from idle.
- locktorture.torture_runnable= [BOOT]
- Start locktorture running at boot time.
-
locktorture.torture_type= [KNL]
Specify the locking implementation to test.
This is useful when you use a panic=... timeout and
need the box quickly up again.
+ These settings can be accessed at runtime via
+ the nmi_watchdog and hardlockup_panic sysctls.
+
netpoll.carrier_timeout=
[NET] Specifies amount of time (in seconds) that
netpoll should wait for a carrier. By default netpoll
nosmt [KNL,S390] Disable symmetric multithreading (SMT).
Equivalent to smt=1.
+ nospectre_v2 [X86] Disable all mitigations for the Spectre variant 2
+ (indirect branch prediction) vulnerability. System may
+ allow data leaks with this option, which is equivalent
+ to spectre_v2=off.
+
noxsave [BUGS=X86] Disables x86 extended register state save
and restore using xsave. The kernel will fallback to
enabling legacy floating-point and sse state.
Valid arguments: on, off
Default: on
- nohz_full= [KNL,BOOT]
+ nohz_full= [KNL,BOOT,SMP,ISOL]
The argument is a cpu list, as described above.
In kernels built with CONFIG_NO_HZ_FULL=y, set
the specified list of CPUs whose tick will be stopped
pcie_scan_all Scan all possible PCIe devices. Otherwise we
only look for one device below a PCIe downstream
port.
+ big_root_window Try to add a big 64bit memory window to the PCIe
+ root complex on AMD CPUs. Some GFX hardware
+ can resize a BAR to allow access to all VRAM.
+ Adding the window is slightly risky (it may
+ conflict with unreported devices), so this
+ taints the kernel.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
instead using the legacy FADT method
profile= [KNL] Enable kernel profiling via /proc/profile
- Format: [schedule,]<number>
+ Format: [<profiletype>,]<number>
+ Param: <profiletype>: "schedule", "sleep", or "kvm"
+ [defaults to kernel profiling]
Param: "schedule" - profile schedule points.
- Param: <number> - step/bucket size as a power of 2 for
- statistical time based profiling.
Param: "sleep" - profile D-state sleeping (millisecs).
Requires CONFIG_SCHEDSTATS
Param: "kvm" - profile VM exits.
+ Param: <number> - step/bucket size as a power of 2 for
+ statistical time based profiling.
prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
before loading.
pt. [PARIDE]
See Documentation/blockdev/paride.txt.
+ 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.
+
+ on - unconditionally enable
+ off - unconditionally disable
+ auto - kernel detects whether your CPU model is
+ vulnerable to issues that PTI mitigates
+
+ Not specifying this option is equivalent to pti=auto.
+
+ nopti [X86_64]
+ Equivalent to pti=off
+
pty.legacy_count=
[KNL] Number of legacy pty's. Overwrites compiled-in
default number.
the same as for rcuperf.nreaders.
N, where N is the number of CPUs
- rcuperf.perf_runnable= [BOOT]
- Start rcuperf running at boot time.
-
rcuperf.perf_type= [KNL]
Specify the RCU implementation to test.
Test RCU's dyntick-idle handling. See also the
rcutorture.shuffle_interval parameter.
- rcutorture.torture_runnable= [BOOT]
- Start rcutorture running at boot time.
-
rcutorture.torture_type= [KNL]
Specify the RCU implementation to test.
rdt= [HW,X86,RDT]
Turn on/off individual RDT features. List is:
- cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, mba.
+ cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
+ mba.
E.g. to turn on cmt and turn off mba use:
rdt=cmt,!mba
sonypi.*= [HW] Sony Programmable I/O Control Device driver
See Documentation/laptops/sonypi.txt
+ spectre_v2= [X86] Control mitigation of Spectre variant 2
+ (indirect branch speculation) vulnerability.
+
+ on - unconditionally enable
+ off - unconditionally disable
+ auto - kernel detects whether your CPU model is
+ vulnerable
+
+ Selecting 'on' will, and 'auto' may, choose a
+ mitigation method at run time according to the
+ CPU, the available microcode, the setting of the
+ CONFIG_RETPOLINE configuration option, and the
+ compiler with which the kernel was built.
+
+ Specific mitigations can also be selected manually:
+
+ retpoline - replace indirect branches
+ retpoline,generic - google's original retpoline
+ retpoline,amd - AMD-specific minimal thunk
+
+ Not specifying this option is equivalent to
+ spectre_v2=auto.
+
spia_io_base= [HW,MTD]
spia_fio_base=
spia_pedr=