diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 546 |
1 files changed, 422 insertions, 124 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f2040d46f095..aefd358a5ca3 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -106,11 +106,11 @@ use by PCI Format: <irq>,<irq>... - acpi_mask_gpe= [HW,ACPI] + acpi_mask_gpe= [HW,ACPI] Due to the existence of _Lxx/_Exx, some GPEs triggered by unsupported hardware/firmware features can result in - GPE floodings that cannot be automatically disabled by - the GPE dispatcher. + GPE floodings that cannot be automatically disabled by + the GPE dispatcher. This facility can be used to prevent such uncontrolled GPE floodings. Format: <int> @@ -256,7 +256,7 @@ (may crash computer or cause data corruption) ALSA [HW,ALSA] - See Documentation/sound/alsa/alsa-parameters.txt + See Documentation/sound/alsa-configuration.rst alignment= [KNL,ARM] Allow the default userspace alignment fault handler @@ -472,10 +472,10 @@ for platform specific values (SB1, Loongson3 and others). - ccw_timeout_log [S390] + ccw_timeout_log [S390] See Documentation/s390/CommonIO for details. - cgroup_disable= [KNL] Disable a particular controller + cgroup_disable= [KNL] Disable a particular controller Format: {name of the controller(s) to disable} The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in @@ -518,7 +518,7 @@ those clocks in any way. This parameter is useful for debug and development, but should not be needed on a platform with proper driver support. For more - information, see Documentation/clk.txt. + information, see Documentation/driver-api/clk.rst. clock= [BUGS=X86-32, HW] gettimeofday clocksource override. [Deprecated] @@ -587,11 +587,6 @@ Sets the size of memory pool for coherent, atomic dma allocations, by default set to 256K. - code_bytes [X86] How many bytes of object code to print - in an oops report. - Range: 0 - 8192 - Default: 64 - com20020= [HW,NET] ARCnet - COM20020 chipset Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] @@ -641,8 +636,8 @@ hvc<n> Use the hypervisor console device <n>. This is for both Xen and PowerPC hypervisors. - If the device connected to the port is not a TTY but a braille - device, prepend "brl," before the device type, for instance + If the device connected to the port is not a TTY but a braille + device, prepend "brl," before the device type, for instance console=brl,ttyS0 For now, only VisioBraille is supported. @@ -662,7 +657,7 @@ consoleblank= [KNL] The console blank (screen saver) timeout in seconds. A value of 0 disables the blank timer. - Defaults to 0. + Defaults to 0. coredump_filter= [KNL] Change the default value for @@ -730,7 +725,7 @@ or memory reserved is below 4G. cryptomgr.notests - [KNL] Disable crypto self-tests + [KNL] Disable crypto self-tests cs89x0_dma= [HW,NET] Format: <dma> @@ -746,13 +741,21 @@ Format: <port#>,<type> See also Documentation/input/devices/joystick-parport.rst - ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot + ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot time. See Documentation/admin-guide/dynamic-debug-howto.rst for details. Deprecated, see dyndbg. debug [KNL] Enable kernel debugging (events log level). + debug_boot_weak_hash + [KNL] Enable printing [hashed] pointers early in the + boot sequence. If enabled, we use a weak hash instead + of siphash to hash pointers. Use this option if you are + seeing instances of '(___ptrval___)') and need to see a + value (hashed pointer) instead. Cryptographically + insecure, please do not use on production kernels. + debug_locks_verbose= [KNL] verbose self-tests Format=<0|1> @@ -809,6 +812,15 @@ Defaults to the default architecture's huge page size if not specified. + deferred_probe_timeout= + [KNL] Debugging option to set a timeout in seconds for + deferred probe to give up waiting on dependencies to + probe. Only specific dependencies (subsystems or + drivers) that have opted in will be ignored. A timeout of 0 + will timeout at the end of initcalls. This option will also + dump out devices still on the deferred probe list after + retrying. + dhash_entries= [KNL] Set number of hash buckets for dentry cache. @@ -821,6 +833,17 @@ disable= [IPV6] See Documentation/networking/ipv6.txt. + hardened_usercopy= + [KNL] Under CONFIG_HARDENED_USERCOPY, whether + hardening is enabled for this boot. Hardened + usercopy checking is used to protect the kernel + from reading or writing beyond known memory + allocation boundaries as a proactive defense + against bounds-checking flaws in the kernel's + copy_to_user()/copy_from_user() interface. + on Perform hardened usercopy checks (default). + off Disable hardened usercopy checks. + disable_radix [PPC] Disable RADIX MMU mode on POWER9 @@ -833,7 +856,13 @@ causing system reset or hang due to sending INIT from AP to BSP. - disable_ddw [PPC/PSERIES] + perf_v4_pmi= [X86,INTEL] + Format: <bool> + Disable Intel PMU counter freezing feature. + The feature only exists starting from + Arch Perfmon v4 (Skylake and newer). + + disable_ddw [PPC/PSERIES] Disable Dynamic DMA Window support. Use this if to workaround buggy firmware. @@ -1025,6 +1054,12 @@ address. The serial port must already be setup and configured. Options are not yet supported. + qcom_geni,<addr> + Start an early, polled-mode console on a Qualcomm + Generic Interface (GENI) based serial port at the + specified address. The serial port must already be + setup and configured. Options are not yet supported. + earlyprintk= [X86,SH,ARM,M68k,S390] earlyprintk=vga earlyprintk=efi @@ -1034,7 +1069,7 @@ earlyprintk=serial[,0x...[,baudrate]] earlyprintk=ttySn[,baudrate] earlyprintk=dbgp[debugController#] - earlyprintk=pciserial,bus:device.function[,baudrate] + earlyprintk=pciserial[,force],bus:device.function[,baudrate] earlyprintk=xdbc[xhciController#] earlyprintk is useful when the kernel crashes before @@ -1066,6 +1101,10 @@ The sclp output can only be used on s390. + The optional "force" to "pciserial" enables use of a + PCI device even when its classcode is not of the + UART class. + edac_report= [HW,EDAC] Control how to report EDAC event Format: {"on" | "off" | "force"} on: enable EDAC to report H/W event. May be overridden @@ -1188,7 +1227,7 @@ parameter will force ia64_sal_cache_flush to call ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. - forcepae [X86-32] + forcepae [X86-32] Forcefully enable Physical Address Extension (PAE). Many Pentium M systems disable PAE but may have a functionally usable PAE implementation. @@ -1247,7 +1286,7 @@ 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 @@ -1341,11 +1380,25 @@ x86-64 are 2M (when the CPU supports "pse") and 1G (when the CPU supports the "pdpe1gb" cpuinfo flag). - hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) - terminal devices. Valid values: 0..8 - hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. - If specified, z/VM IUCV HVC accepts connections - from listed z/VM user IDs only. + hung_task_panic= + [KNL] Should the hung task detector generate panics. + Format: <integer> + + A nonzero value instructs the kernel to panic when a + hung task is detected. The default value is controlled + by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time + option. The value selected by this boot parameter can + be changed later by the kernel.hung_task_panic sysctl. + + hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) + terminal devices. Valid values: 0..8 + hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. + If specified, z/VM IUCV HVC accepts connections + from listed z/VM user IDs only. + + hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations + which allow the hypervisor to 'idle' the + guest on lock contention. keep_bootcon [KNL] Do not unregister boot console at start. This is only @@ -1353,11 +1406,11 @@ between unregistering the boot console and initializing the real console. - i2c_bus= [HW] Override the default board specific I2C bus speed - or register an additional I2C bus that is not - registered from board initialization code. - Format: - <bus_id>,<clkrate> + i2c_bus= [HW] Override the default board specific I2C bus speed + or register an additional I2C bus that is not + registered from board initialization code. + Format: + <bus_id>,<clkrate> i8042.debug [HW] Toggle i8042 debug mode i8042.unmask_kbd_data @@ -1386,7 +1439,7 @@ Default: only on s2r transitions on x86; most other architectures force reset to be always executed i8042.unlock [HW] Unlock (ignore) the keylock - i8042.kbdreset [HW] Reset device connected to KBD port + i8042.kbdreset [HW] Reset device connected to KBD port i810= [HW,DRM] @@ -1548,13 +1601,13 @@ programs exec'd, files mmap'd for exec, and all files opened for read by uid=0. - ima_template= [IMA] + ima_template= [IMA] Select one of defined IMA measurements template formats. Formats: { "ima" | "ima-ng" | "ima-sig" } Default: "ima-ng" ima_template_fmt= - [IMA] Define a custom template format. + [IMA] Define a custom template format. Format: { "field1|...|fieldN" } ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage @@ -1597,7 +1650,7 @@ 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" } @@ -1650,39 +1703,39 @@ 0 disables intel_idle and fall back on acpi_idle. 1 to 9 specify maximum depth of C-state. - intel_pstate= [X86] - disable - Do not enable intel_pstate as the default - scaling driver for the supported processors - passive - Use intel_pstate as a scaling driver, but configure it - to work with generic cpufreq governors (instead of - enabling its internal governor). This mode cannot be - used along with the hardware-managed P-states (HWP) - feature. - force - Enable intel_pstate on systems that prohibit it by default - in favor of acpi-cpufreq. Forcing the intel_pstate driver - instead of acpi-cpufreq may disable platform features, such - as thermal controls and power capping, that rely on ACPI - P-States information being indicated to OSPM and therefore - should be used with caution. This option does not work with - processors that aren't supported by the intel_pstate driver - or on platforms that use pcc-cpufreq instead of acpi-cpufreq. - no_hwp - Do not enable hardware P state control (HWP) - if available. - hwp_only - Only load intel_pstate on systems which support - hardware P state control (HWP) if available. - support_acpi_ppc - Enforce ACPI _PPC performance limits. If the Fixed ACPI - Description Table, specifies preferred power management - profile as "Enterprise Server" or "Performance Server", - then this feature is turned on by default. - per_cpu_perf_limits - Allow per-logical-CPU P-State performance control limits using - cpufreq sysfs interface + intel_pstate= [X86] + disable + Do not enable intel_pstate as the default + scaling driver for the supported processors + passive + Use intel_pstate as a scaling driver, but configure it + to work with generic cpufreq governors (instead of + enabling its internal governor). This mode cannot be + used along with the hardware-managed P-states (HWP) + feature. + force + Enable intel_pstate on systems that prohibit it by default + in favor of acpi-cpufreq. Forcing the intel_pstate driver + instead of acpi-cpufreq may disable platform features, such + as thermal controls and power capping, that rely on ACPI + P-States information being indicated to OSPM and therefore + should be used with caution. This option does not work with + processors that aren't supported by the intel_pstate driver + or on platforms that use pcc-cpufreq instead of acpi-cpufreq. + no_hwp + Do not enable hardware P state control (HWP) + if available. + hwp_only + Only load intel_pstate on systems which support + hardware P state control (HWP) if available. + support_acpi_ppc + Enforce ACPI _PPC performance limits. If the Fixed ACPI + Description Table, specifies preferred power management + profile as "Enterprise Server" or "Performance Server", + then this feature is turned on by default. + per_cpu_perf_limits + Allow per-logical-CPU P-State performance control limits using + cpufreq sysfs interface intremap= [X86-64, Intel-IOMMU] on enable Interrupt Remapping (default) @@ -1705,18 +1758,30 @@ nopanic merge nomerge - forcesac soft - pt [x86, IA-64] + pt [x86] + nopt [x86] nobypass [PPC/POWERNV] Disable IOMMU bypass, using IOMMU for PCI devices. + iommu.strict= [ARM64] Configure TLB invalidation behaviour + Format: { "0" | "1" } + 0 - Lazy mode. + Request that DMA unmap operations use deferred + invalidation of hardware TLBs, for increased + throughput at the cost of reduced device isolation. + Will fall back to strict mode if not supported by + the relevant IOMMU driver. + 1 - Strict mode (default). + DMA unmap operations invalidate IOMMU hardware TLBs + synchronously. + iommu.passthrough= [ARM64] Configure DMA to bypass the IOMMU by default. Format: { "0" | "1" } 0 - Use IOMMU translation for DMA. 1 - Bypass the IOMMU for DMA. - unset - Use IOMMU translation for DMA. + unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. io7= [HW] IO7 for Marvel based alpha systems See comment before marvel_specify_io7 in @@ -1958,10 +2023,84 @@ (virtualized real and unpaged mode) on capable Intel chips. Default is 1 (enabled) + kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault + CVE-2018-3620. + + Valid arguments: never, cond, always + + always: L1D cache flush on every VMENTER. + cond: Flush L1D on VMENTER only when the code between + VMEXIT and VMENTER can leak host memory. + never: Disables the mitigation + + Default is cond (do L1 cache flush in specific instances) + kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification feature (tagged TLBs) on capable Intel chips. Default is 1 (enabled) + l1tf= [X86] Control mitigation of the L1TF vulnerability on + affected CPUs + + The kernel PTE inversion protection is unconditionally + enabled and cannot be disabled. + + full + Provides all available mitigations for the + L1TF vulnerability. Disables SMT and + enables all mitigations in the + hypervisors, i.e. unconditional L1D flush. + + SMT control and L1D flush control via the + sysfs interface is still possible after + boot. Hypervisors will issue a warning + when the first VM is started in a + potentially insecure configuration, + i.e. SMT enabled or L1D flush disabled. + + full,force + Same as 'full', but disables SMT and L1D + flush runtime control. Implies the + 'nosmt=force' command line option. + (i.e. sysfs control of SMT is disabled.) + + flush + Leaves SMT enabled and enables the default + hypervisor mitigation, i.e. conditional + L1D flush. + + SMT control and L1D flush control via the + sysfs interface is still possible after + boot. Hypervisors will issue a warning + when the first VM is started in a + potentially insecure configuration, + i.e. SMT enabled or L1D flush disabled. + + flush,nosmt + + Disables SMT and enables the default + hypervisor mitigation. + + SMT control and L1D flush control via the + sysfs interface is still possible after + boot. Hypervisors will issue a warning + when the first VM is started in a + potentially insecure configuration, + i.e. SMT enabled or L1D flush disabled. + + flush,nowarn + Same as 'flush', but hypervisors will not + warn when a VM is started in a potentially + insecure configuration. + + off + Disables hypervisor mitigations and doesn't + emit any warnings. + + Default is 'flush'. + + For details see: Documentation/admin-guide/l1tf.rst + l2cr= [PPC] l3cr= [PPC] @@ -2027,7 +2166,7 @@ * [no]ncqtrim: Turn off queued DSM TRIM. * nohrst, nosrst, norst: suppress hard, soft - and both resets. + and both resets. * rstonce: only attempt one reset during hot-unplug link recovery @@ -2162,6 +2301,8 @@ ltpc= [NET] Format: <io>,<irq>,<dma> + lsm.debug [SECURITY] Enable LSM initialization debugging output. + machvec= [IA-64] Force the use of a particular machine-vector (machvec) in a generic kernel. Example: machvec=hpzx1_swiotlb @@ -2215,7 +2356,7 @@ [KNL,SH] Allow user to override the default size for per-device physically contiguous DMA buffers. - memhp_default_state=online/offline + memhp_default_state=online/offline [KNL] Set the initial state for the memory hotplug onlining policy. If not specified, the default value is set according to the @@ -2292,7 +2433,7 @@ seconds. Use this parameter to check at some other rate. 0 disables periodic checking. - memtest= [KNL,X86,ARM] Enable memtest + memtest= [KNL,X86,ARM,PPC] Enable memtest Format: <integer> default : 0 <disable> Specifies the number of memtest passes to be @@ -2600,6 +2741,9 @@ emulation library even if a 387 maths coprocessor is present. + no5lvl [X86-64] Disable 5-level paging mode. Forces + kernel to use 4-level paging instead. + no_console_suspend [HW] Never suspend the console Disable suspending of consoles during suspend and @@ -2675,6 +2819,14 @@ nosmt [KNL,S390] Disable symmetric multithreading (SMT). Equivalent to smt=1. + [KNL,x86] Disable symmetric multithreading (SMT). + nosmt=force: Force disable SMT, cannot be undone + via the sysfs control file. + + nospectre_v1 [PPC] Disable mitigations for Spectre Variant 1 (bounds + check bypass). With this option data leaks are possible + in the system. + 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 @@ -2765,7 +2917,7 @@ [X86,PV_OPS] Disable paravirtualized VMware scheduler clock and use the default one. - no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. + no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. steal time is computed, but won't influence scheduler behaviour @@ -2823,10 +2975,8 @@ nosync [HW,M68K] Disables sync negotiation for all devices. - notsc [BUGS=X86-32] Disable Time Stamp Counter - nowatchdog [KNL] Disable both lockup detectors, i.e. - soft-lockup and NMI watchdog (hard-lockup). + soft-lockup and NMI watchdog (hard-lockup). nowb [ARM] @@ -2846,7 +2996,7 @@ If the dependencies are under your control, you can turn on cpu0_hotplug. - nps_mtm_hs_ctr= [KNL,ARC] + nps_mtm_hs_ctr= [KNL,ARC] This parameter sets the maximum duration, in cycles, each HW thread of the CTOP can run without interruptions, before HW switches it. @@ -2914,9 +3064,6 @@ This will also cause panics on machine check exceptions. Useful together with panic=30 to trigger a reboot. - OSS [HW,OSS] - See Documentation/sound/oss/oss-parameters.txt - page_owner= [KNL] Boot-time page_owner enabling option. Storage of the information about who allocated each page is disabled in default. With this switch, @@ -2924,8 +3071,9 @@ on: enable the feature page_poison= [KNL] Boot-time parameter changing the state of - poisoning on the buddy allocator. - off: turn off poisoning + poisoning on the buddy allocator, available with + CONFIG_PAGE_POISONING=y. + off: turn off poisoning (default) on: turn on poisoning panic= [KNL] Kernel behaviour on panic: delay <timeout> @@ -2985,9 +3133,32 @@ See header of drivers/block/paride/pcd.c. See also Documentation/blockdev/paride.txt. - pci=option[,option...] [PCI] various PCI subsystem options: - earlydump [X86] dump PCI config space before the kernel - changes anything + pci=option[,option...] [PCI] various PCI subsystem options. + + Some options herein operate on a specific device + or a set of devices (<pci_dev>). These are + specified in one of the following formats: + + [<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]* + pci:<vendor>:<device>[:<subvendor>:<subdevice>] + + Note: the first format specifies a PCI + bus/device/function address which may change + if new hardware is inserted, if motherboard + firmware changes, or due to changes caused + by other kernel parameters. If the + domain is left unspecified, it is + taken to be zero. Optionally, a path + to a device through multiple device/function + addresses can be specified after the base + address (this is more robust against + renumbering issues). The second format + selects devices using IDs from the + configuration space which may match multiple + devices in the system. + + earlydump dump PCI config space before the kernel + changes anything off [X86] don't probe for the PCI bus bios [X86-32] force use of PCI BIOS, don't access the hardware directly. Use this if your machine @@ -3075,7 +3246,7 @@ is enabled by default. If you need to use this, please report a bug. nocrs [X86] Ignore PCI host bridge windows from ACPI. - If you need to use this, please report a bug. + If you need to use this, please report a bug. routeirq Do IRQ routing for all PCI devices. This is normally done in pci_enable_device(), so this option is a temporary workaround @@ -3114,11 +3285,10 @@ window. The default value is 64 megabytes. resource_alignment= Format: - [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] - [<order of align>@]pci:<vendor>:<device>\ - [:<subvendor>:<subdevice>][; ...] + [<order of align>@]<pci_dev>[; ...] Specifies alignment and device to reassign - aligned memory resources. + aligned memory resources. How to + specify the device is described above. If <order of align> is not specified, PAGE_SIZE is used as alignment. PCI-PCI bridge can be specified, if resource @@ -3150,6 +3320,8 @@ on: Turn realloc on realloc same as realloc=on noari do not use PCIe ARI. + noats [PCIE, Intel-IOMMU, AMD-IOMMU] + do not use PCIe ATS (and IOMMU device IOTLB). pcie_scan_all Scan all possible PCIe devices. Otherwise we only look for one device below a PCIe downstream port. @@ -3159,6 +3331,15 @@ Adding the window is slightly risky (it may conflict with unreported devices), so this taints the kernel. + disable_acs_redir=<pci_dev>[; ...] + Specify one or more PCI devices (in the format + specified above) separated by semicolons. + Each device specified will have the PCI ACS + redirect capabilities forced off which will + allow P2P traffic between devices through + bridges without forcing it upstream. Note: + this removes isolation between devices and + may put more devices in an IOMMU group. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power Management. @@ -3324,6 +3505,10 @@ before loading. See Documentation/blockdev/ramdisk.txt. + psi= [KNL] Enable or disable pressure stall information + tracking. + Format: <bool> + psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to probe for; one of (bare|imps|exps|lifebook|any). psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports @@ -3371,6 +3556,12 @@ ramdisk_size= [RAM] Sizes of RAM disks in kilobytes See Documentation/blockdev/ramdisk.txt. + random.trust_cpu={on,off} + [KNL] Enable or disable trusting the use of the + CPU's random number generator (if available) to + fully seed the kernel's CRNG. Default is controlled + by CONFIG_RANDOM_TRUST_CPU. + ras=option[,option,...] [KNL] RAS-specific options cec_disable [X86] @@ -3382,14 +3573,14 @@ 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 "b" for RCU-bh, "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. + 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_nocb_poll [KNL] Rather than requiring that offloaded CPUs @@ -3443,7 +3634,14 @@ Set required age in jiffies for a given grace period before RCU starts soliciting quiescent-state help from - rcu_note_context_switch(). + rcu_note_context_switch(). If not specified, the + kernel will calculate a value based on the most + recent settings of rcutree.jiffies_till_first_fqs + and rcutree.jiffies_till_next_fqs. + This calculated value may be viewed in + rcutree.jiffies_to_sched_qs. Any attempt to + set rcutree.jiffies_to_sched_qs will be + cheerfully overwritten. rcutree.jiffies_till_first_fqs= [KNL] Set delay from grace-period initialization to @@ -3621,8 +3819,8 @@ Set time (s) after boot for CPU-hotplug testing. rcutorture.onoff_interval= [KNL] - Set time (s) between CPU-hotplug operations, or - zero to disable CPU-hotplug testing. + Set time (jiffies) between CPU-hotplug operations, + or zero to disable CPU-hotplug testing. rcutorture.shuffle_interval= [KNL] Set task-shuffle interval (s). Shuffling tasks @@ -3711,12 +3909,6 @@ rcupdate.rcu_self_test= [KNL] Run the RCU early boot self tests - rcupdate.rcu_self_test_bh= [KNL] - Run the RCU bh early boot self tests - - rcupdate.rcu_self_test_sched= [KNL] - Run the RCU sched early boot self tests - rdinit= [KNL] Format: <full_path> Run specified binary instead of /init from the ramdisk, @@ -3918,7 +4110,7 @@ cache (risks via metadata attacks are mostly unchanged). Debug options disable merging on their own. - For more information see Documentation/vm/slub.txt. + For more information see Documentation/vm/slub.rst. slab_max_order= [MM, SLAB] Determines the maximum allowed order for slabs. @@ -3932,7 +4124,7 @@ slub_debug can create guard zones around objects and may poison objects when not in use. Also tracks the last alloc / free. For more information see - Documentation/vm/slub.txt. + Documentation/vm/slub.rst. slub_memcg_sysfs= [MM, SLUB] Determines whether to enable sysfs directories for @@ -3946,7 +4138,7 @@ Determines the maximum allowed order for slabs. A high setting may cause OOMs due to memory fragmentation. For more information see - Documentation/vm/slub.txt. + Documentation/vm/slub.rst. slub_min_objects= [MM, SLUB] The minimum number of objects per slab. SLUB will @@ -3955,12 +4147,12 @@ the number of objects indicated. The higher the number of objects the smaller the overhead of tracking slabs and the less frequently locks need to be acquired. - For more information see Documentation/vm/slub.txt. + For more information see Documentation/vm/slub.rst. slub_min_order= [MM, SLUB] Determines the minimum page order for slabs. Must be lower than slub_max_order. - For more information see Documentation/vm/slub.txt. + For more information see Documentation/vm/slub.rst. slub_nomerge [MM, SLUB] Same with slab_nomerge. This is supported for legacy. @@ -4007,9 +4199,13 @@ spectre_v2= [X86] Control mitigation of Spectre variant 2 (indirect branch speculation) vulnerability. + The default operation protects the kernel from + user space attacks. - on - unconditionally enable - off - unconditionally disable + on - unconditionally enable, implies + spectre_v2_user=on + off - unconditionally disable, implies + spectre_v2_user=off auto - kernel detects whether your CPU model is vulnerable @@ -4019,6 +4215,12 @@ CONFIG_RETPOLINE configuration option, and the compiler with which the kernel was built. + Selecting 'on' will also enable the mitigation + against user space to user space task attacks. + + Selecting 'off' will disable both the kernel and + the user space protections. + Specific mitigations can also be selected manually: retpoline - replace indirect branches @@ -4028,6 +4230,48 @@ Not specifying this option is equivalent to spectre_v2=auto. + spectre_v2_user= + [X86] Control mitigation of Spectre variant 2 + (indirect branch speculation) vulnerability between + user space tasks + + on - Unconditionally enable mitigations. Is + enforced by spectre_v2=on + + off - Unconditionally disable mitigations. Is + enforced by spectre_v2=off + + prctl - Indirect branch speculation is enabled, + but mitigation can be enabled via prctl + per thread. The mitigation control state + is inherited on fork. + + prctl,ibpb + - Like "prctl" above, but only STIBP is + controlled per thread. IBPB is issued + always when switching between different user + space processes. + + seccomp + - Same as "prctl" above, but all seccomp + threads will enable the mitigation unless + they explicitly opt out. + + seccomp,ibpb + - Like "seccomp" above, but only STIBP is + controlled per thread. IBPB is issued + always when switching between different + user space processes. + + auto - Kernel selects the mitigation depending on + the available CPU features and vulnerability. + + Default mitigation: + If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl" + + Not specifying this option is equivalent to + spectre_v2_user=auto. + spec_store_bypass_disable= [HW] Control Speculative Store Bypass (SSB) Disable mitigation (Speculative Store Bypass vulnerability) @@ -4049,6 +4293,8 @@ This parameter controls whether the Speculative Store Bypass optimization is used. + On x86 the options are: + on - Unconditionally disable Speculative Store Bypass off - Unconditionally enable Speculative Store Bypass auto - Kernel detects whether the CPU model contains an @@ -4064,12 +4310,20 @@ seccomp - Same as "prctl" above, but all seccomp threads will disable SSB unless they explicitly opt out. - Not specifying this option is equivalent to - spec_store_bypass_disable=auto. - Default mitigations: X86: If CONFIG_SECCOMP=y "seccomp", otherwise "prctl" + On powerpc the options are: + + on,auto - On Power8 and Power9 insert a store-forwarding + barrier on kernel entry and exit. On Power7 + perform a software flush on kernel entry and + exit. + off - No action. + + Not specifying this option is equivalent to + spec_store_bypass_disable=auto. + spia_io_base= [HW,MTD] spia_fio_base= spia_pedr= @@ -4092,6 +4346,23 @@ expediting. Set to zero to disable automatic expediting. + ssbd= [ARM64,HW] + Speculative Store Bypass Disable control + + On CPUs that are vulnerable to the Speculative + Store Bypass vulnerability and offer a + firmware based mitigation, this parameter + indicates how the mitigation should be used: + + force-on: Unconditionally enable mitigation for + for both kernel and userspace + force-off: Unconditionally disable mitigation for + for both kernel and userspace + kernel: Always enable mitigation in the + kernel, and offer a prctl interface + to allow userspace to register its + interest in being mitigated too. + stack_guard_gap= [MM] override the default stack gap protection. The value is in page units and it defines how many pages prior @@ -4304,7 +4575,7 @@ [FTRACE] Set and start specified trace events in order to facilitate early boot debugging. The event-list is a comma separated list of trace events to enable. See - also Documentation/trace/events.txt + also Documentation/trace/events.rst trace_options=[option-list] [FTRACE] Enable or disable tracer options at boot. @@ -4319,7 +4590,7 @@ trace_options=stacktrace - See also Documentation/trace/ftrace.txt "trace options" + See also Documentation/trace/ftrace.rst "trace options" section. tp_printk[FTRACE] @@ -4358,7 +4629,8 @@ Format: [always|madvise|never] Can be used to control the default behavior of the system with respect to transparent hugepages. - See Documentation/vm/transhuge.txt for more details. + See Documentation/admin-guide/mm/transhuge.rst + for more details. tsc= Disable clocksource stability checks for TSC. Format: <string> @@ -4424,7 +4696,8 @@ usbcore.old_scheme_first= [USB] Start with the old device initialization - scheme (default 0 = off). + scheme, applies only to low and full-speed devices + (default 0 = off). usbcore.usbfs_memory_mb= [USB] Memory limit (in MB) for buffers allocated by @@ -4436,7 +4709,7 @@ usbcore.initial_descriptor_timeout= [USB] Specifies timeout for the initial 64-byte - USB_REQ_GET_DESCRIPTOR request in milliseconds + USB_REQ_GET_DESCRIPTOR request in milliseconds (default 5000 = 5.0 seconds). usbcore.nousb [USB] Disable the USB subsystem @@ -4497,6 +4770,8 @@ prevent spurious wakeup); n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a pause after every control message); + o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra + delay after resetting its port); Example: quirks=0781:5580:bk,0a5c:5834:gij usbhid.mousepoll= @@ -4639,6 +4914,18 @@ This is actually a boot loader parameter; the value is passed to the kernel using a special protocol. + vm_debug[=options] [KNL] Available with CONFIG_DEBUG_VM=y. + May slow down system boot speed, especially when + enabled on systems with a large amount of memory. + All options are enabled by default, and this + interface is meant to allow for selectively + enabling or disabling specific virtual memory + debugging features. + + Available options are: + P Enable page structure init time poisoning + - Disable all of the above options + vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact size of <nn>. This can be used to increase the minimum size (128MB on x86). It can also be used to @@ -4814,6 +5101,17 @@ Disables the PV optimizations forcing the HVM guest to run as generic HVM guest with no PV drivers. + xen_scrub_pages= [XEN] + Boolean option to control scrubbing pages before giving them back + to Xen, for use by other domains. Can be also changed at runtime + with /sys/devices/system/xen_memory/xen_memory0/scrub_pages. + Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT. + xirc2ps_cs= [NET,PCMCIA] Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] + + xhci-hcd.quirks [USB,KNL] + A hex value specifying bitmask with supplemental xhci + host controller quirks. Meaning of each bit can be + consulted in header drivers/usb/host/xhci.h. |