diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 124 |
1 files changed, 97 insertions, 27 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 9725c546a0d4..f5a27f067db9 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -225,14 +225,23 @@ For broken nForce2 BIOS resulting in XT-PIC timer. acpi_sleep= [HW,ACPI] Sleep options - Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, - old_ordering, nonvs, sci_force_enable, nobl } + Format: { s3_bios, s3_mode, s3_beep, s4_hwsig, + s4_nohwsig, old_ordering, nonvs, + sci_force_enable, nobl } See Documentation/power/video.rst for information on s3_bios and s3_mode. s3_beep is for debugging; it makes the PC's speaker beep as soon as the kernel's real-mode entry point is called. + s4_hwsig causes the kernel to check the ACPI hardware + signature during resume from hibernation, and gracefully + refuse to resume if it has changed. This complies with + the ACPI specification but not with reality, since + Windows does not do this and many laptops do change it + on docking. So the default behaviour is to allow resume + and simply warn when the signature changes, unless the + s4_hwsig option is enabled. s4_nohwsig prevents ACPI hardware signature from being - used during resume from hibernation. + used (or even warned about) during resume. old_ordering causes the ACPI 1.0 ordering of the _PTS control method, with respect to putting devices into low power states, to be enforced (the ACPI 2.0 ordering @@ -603,8 +612,8 @@ 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. + unstable. Defaults to two retries, that is, + three attempts to read the clock under test. clocksource.verify_n_cpus= [KNL] Limit the number of CPUs checked for clocksources @@ -1689,6 +1698,8 @@ architectures force reset to be always executed i8042.unlock [HW] Unlock (ignore) the keylock i8042.kbdreset [HW] Reset device connected to KBD port + i8042.probe_defer + [HW] Allow deferred probing upon i8042 probe errors i810= [HW,DRM] @@ -2413,8 +2424,12 @@ Default is 1 (enabled) kvm-intel.emulate_invalid_guest_state= - [KVM,Intel] Enable emulation of invalid guest states - Default is 0 (disabled) + [KVM,Intel] Disable emulation of invalid guest state. + Ignored if kvm-intel.enable_unrestricted_guest=1, as + guest state is never invalid for unrestricted guests. + This param doesn't apply to nested guests (L2), as KVM + never emulates invalid L2 guest state. + Default is 1 (enabled) kvm-intel.flexpriority= [KVM,Intel] Disable FlexPriority feature (TPR shadow). @@ -2934,7 +2949,7 @@ both parameters are enabled, hugetlb_free_vmemmap takes precedence over memory_hotplug.memmap_on_memory. - memtest= [KNL,X86,ARM,PPC,RISCV] Enable memtest + memtest= [KNL,X86,ARM,M68K,PPC,RISCV] Enable memtest Format: <integer> default : 0 <disable> Specifies the number of memtest passes to be @@ -3378,7 +3393,7 @@ Disable SMAP (Supervisor Mode Access Prevention) even if it is supported by processor. - nosmep [X86,PPC] + nosmep [X86,PPC64s] Disable SMEP (Supervisor Mode Execution Prevention) even if it is supported by processor. @@ -3545,6 +3560,13 @@ shutdown the other cpus. Instead use the REBOOT_VECTOR irq. + nomodeset Disable kernel modesetting. DRM drivers will not perform + display-mode changes or accelerated rendering. Only the + system framebuffer will be available for use if this was + set-up by the firmware or boot loader. + + Useful as fallback, or for testing and debugging. + nomodule Disable module load nopat [X86] Disable PAT (page attribute table extension of @@ -4144,6 +4166,14 @@ Override pmtimer IOPort with a hex value. e.g. pmtmr=0x508 + pmu_override= [PPC] Override the PMU. + This option takes over the PMU facility, so it is no + longer usable by perf. Setting this option starts the + PMU counters by setting MMCR0 to 0 (the FC bit is + cleared). If a number is given, then MMCR1 is set to + that number, otherwise (e.g., 'pmu_override=on'), MMCR1 + remains 0. + pm_debug_messages [SUSPEND,KNL] Enable suspend/resume debug messages during boot up. @@ -4343,19 +4373,30 @@ Disable the Correctable Errors Collector, see CONFIG_RAS_CEC help text. - rcu_nocbs= [KNL] - The argument is a cpu list, as described above. - - In kernels built with CONFIG_RCU_NOCB_CPU=y, set - the specified list of CPUs to be no-callback CPUs. - Invocation of these CPUs' RCU callbacks will be - offloaded to "rcuox/N" kthreads created for that - purpose, where "x" is "p" for RCU-preempt, and - "s" for RCU-sched, and "N" is the CPU number. - This reduces OS jitter on the offloaded CPUs, - which can be useful for HPC and real-time - workloads. It can also improve energy efficiency - for asymmetric multiprocessors. + rcu_nocbs[=cpu-list] + [KNL] The optional argument is a cpu list, + as described above. + + In kernels built with CONFIG_RCU_NOCB_CPU=y, + enable the no-callback CPU mode, which prevents + such CPUs' callbacks from being invoked in + softirq context. Invocation of such CPUs' RCU + callbacks will instead be offloaded to "rcuox/N" + kthreads created for that purpose, where "x" is + "p" for RCU-preempt, "s" for RCU-sched, and "g" + for the kthreads that mediate grace periods; and + "N" is the CPU number. This reduces OS jitter on + the offloaded CPUs, which can be useful for HPC + and real-time workloads. It can also improve + energy efficiency for asymmetric multiprocessors. + + If a cpulist is passed as an argument, the specified + list of CPUs is set to no-callback mode from boot. + + Otherwise, if the '=' sign and the cpulist + arguments are omitted, no CPU will be set to + no-callback mode from boot but the mode may be + toggled at runtime via cpusets. rcu_nocb_poll [KNL] Rather than requiring that offloaded CPUs @@ -4489,10 +4530,6 @@ on rcutree.qhimark at boot time and to zero to disable more aggressive help enlistment. - rcutree.rcu_idle_gp_delay= [KNL] - Set wakeup interval for idle CPUs that have - RCU callbacks (RCU_FAST_NO_HZ=y). - rcutree.rcu_kick_kthreads= [KNL] Cause the grace-period kthread to get an extra wake_up() if it sleeps three times longer than @@ -4603,8 +4640,12 @@ in seconds. rcutorture.fwd_progress= [KNL] - Enable RCU grace-period forward-progress testing + Specifies the number of kthreads to be used + for RCU grace-period forward-progress testing for the types of RCU supporting this notion. + Defaults to 1 kthread, values less than zero or + greater than the number of CPUs cause the number + of CPUs to be used. rcutorture.fwd_progress_div= [KNL] Specify the fraction of a CPU-stall-warning @@ -4805,6 +4846,29 @@ period to instead use normal non-expedited grace-period processing. + rcupdate.rcu_task_collapse_lim= [KNL] + Set the maximum number of callbacks present + at the beginning of a grace period that allows + the RCU Tasks flavors to collapse back to using + a single callback queue. This switching only + occurs when rcupdate.rcu_task_enqueue_lim is + set to the default value of -1. + + rcupdate.rcu_task_contend_lim= [KNL] + Set the minimum number of callback-queuing-time + lock-contention events per jiffy required to + cause the RCU Tasks flavors to switch to per-CPU + callback queuing. This switching only occurs + when rcupdate.rcu_task_enqueue_lim is set to + the default value of -1. + + rcupdate.rcu_task_enqueue_lim= [KNL] + Set the number of callback queues to use for the + RCU Tasks family of RCU flavors. The default + of -1 allows this to be automatically (and + dynamically) adjusted. This parameter is intended + for use in testing. + rcupdate.rcu_task_ipi_delay= [KNL] Set time in jiffies during which RCU tasks will avoid sending IPIs, starting with the beginning @@ -6438,6 +6502,12 @@ controller on both pseries and powernv platforms. Only useful on POWER9 and above. + xive.store-eoi=off [PPC] + By default on POWER10 and above, the kernel will use + stores for EOI handling when the XIVE interrupt mode + is active. This option allows the XIVE driver to use + loads instead, as on POWER9. + xhci-hcd.quirks [USB,KNL] A hex value specifying bitmask with supplemental xhci host controller quirks. Meaning of each bit can be |