diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 230 |
1 files changed, 210 insertions, 20 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 8f75ec177399..747a55abf494 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -458,6 +458,9 @@ arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory Set instructions support + arm64.nompam [ARM64] Unconditionally disable Memory Partitioning And + Monitoring support + arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension support @@ -630,6 +633,14 @@ named mounts. Specifying both "all" and "named" disables all v1 hierarchies. + cgroup_v1_proc= [KNL] Show also missing controllers in /proc/cgroups + Format: { "true" | "false" } + /proc/cgroups lists only v1 controllers by default. + This compatibility option enables listing also v2 + controllers (whose v1 code is not compiled!), so that + semi-legacy software can check this file to decide + about usage of v2 (sic) controllers. + cgroup_favordynmods= [KNL] Enable or Disable favordynmods. Format: { "true" | "false" } Defaults to the value of CONFIG_CGROUP_FAVOR_DYNMODS. @@ -983,6 +994,28 @@ 0: to disable low allocation. It will be ignored when crashkernel=X,high is not used or memory reserved is below 4G. + crashkernel=size[KMG],cma + [KNL, X86] Reserve additional crash kernel memory from + CMA. This reservation is usable by the first system's + userspace memory and kernel movable allocations (memory + balloon, zswap). Pages allocated from this memory range + will not be included in the vmcore so this should not + be used if dumping of userspace memory is intended and + it has to be expected that some movable kernel pages + may be missing from the dump. + + A standard crashkernel reservation, as described above, + is still needed to hold the crash kernel and initrd. + + This option increases the risk of a kdump failure: DMA + transfers configured by the first kernel may end up + corrupting the second kernel's memory. + + This reservation method is intended for systems that + can't afford to sacrifice enough memory for standard + crashkernel reservation and where less reliable and + possibly incomplete kdump is preferable to no kdump at + all. cryptomgr.notests [KNL] Disable crypto self-tests @@ -1795,6 +1828,27 @@ backtraces on all cpus. Format: 0 | 1 + hash_pointers= + [KNL,EARLY] + By default, when pointers are printed to the console + or buffers via the %p format string, that pointer is + "hashed", i.e. obscured by hashing the pointer value. + This is a security feature that hides actual kernel + addresses from unprivileged users, but it also makes + debugging the kernel more difficult since unequal + pointers can no longer be compared. The choices are: + Format: { auto | always | never } + Default: auto + + auto - Hash pointers unless slab_debug is enabled. + always - Always hash pointers (even if slab_debug is + enabled). + never - Never hash pointers. This option should only + be specified when debugging the kernel. Do + not use on production kernels. The boot + param "no_hash_pointers" is an alias for + this mode. + hashdist= [KNL,NUMA] Large hashes allocated during boot are distributed across NUMA nodes. Defaults on for 64-bit NUMA, off otherwise. @@ -1828,6 +1882,13 @@ lz4: Select LZ4 compression algorithm to compress/decompress hibernation image. + hibernate.pm_test_delay= + [HIBERNATION] + Sets the number of seconds to remain in a hibernation test + mode before resuming the system (see + /sys/power/pm_test). Only available when CONFIG_PM_DEBUG + is set. Default value is 5. + highmem=nn[KMG] [KNL,BOOT,EARLY] forces the highmem zone to have an exact size of <nn>. This works even on boxes that have no highmem otherwise. This also works to reduce highmem @@ -2202,6 +2263,11 @@ different crypto accelerators. This option can be used to achieve best performance for particular HW. + ima= [IMA] Enable or disable IMA + Format: { "off" | "on" } + Default: "on" + Note that disabling IMA is limited to kdump kernel. + indirect_target_selection= [X86,Intel] Mitigation control for Indirect Target Selection(ITS) bug in Intel CPUs. Updated microcode is also required for a fix in IBPB. @@ -2528,6 +2594,13 @@ requires the kernel to be built with CONFIG_ARM64_PSEUDO_NMI. + irqchip.riscv_imsic_noipi + [RISC-V,EARLY] + Force the kernel to not use IMSIC software injected MSIs + as IPIs. Intended for system where IMSIC is trap-n-emulated, + and thus want to reduce MMIO traps when triggering IPIs + to multiple harts. + irqfixup [HW] When an interrupt is not handled search all handlers for it. Intended to get systems with badly broken @@ -2742,6 +2815,31 @@ kgdbwait [KGDB,EARLY] Stop kernel execution and enter the kernel debugger at the earliest opportunity. + kho= [KEXEC,EARLY] + Format: { "0" | "1" | "off" | "on" | "y" | "n" } + Enables or disables Kexec HandOver. + "0" | "off" | "n" - kexec handover is disabled + "1" | "on" | "y" - kexec handover is enabled + + kho_scratch= [KEXEC,EARLY] + Format: ll[KMG],mm[KMG],nn[KMG] | nn% + Defines the size of the KHO scratch region. The KHO + scratch regions are physically contiguous memory + ranges that can only be used for non-kernel + allocations. That way, even when memory is heavily + fragmented with handed over memory, the kexeced + kernel will always have enough contiguous ranges to + bootstrap itself. + + It is possible to specify the exact amount of + memory in the form of "ll[KMG],mm[KMG],nn[KMG]" + where the first parameter defines the size of a low + memory scratch area, the second parameter defines + the size of a global scratch area and the third + parameter defines the size of additional per-node + scratch areas. The form "nn%" defines scale factor + (in percents) of memory that was used during boot. + kmac= [MIPS] Korina ethernet MAC address. Configure the RouterBoard 532 series on-chip Ethernet adapter MAC address. @@ -3755,6 +3853,10 @@ mmio_stale_data=full,nosmt [X86] retbleed=auto,nosmt [X86] + [X86] After one of the above options, additionally + supports attack-vector based controls as documented in + Documentation/admin-guide/hw-vuln/attack_vector_controls.rst + mminit_loglevel= [KNL,EARLY] When CONFIG_DEBUG_MEMORY_INIT is set, this parameter allows control of the logging verbosity for @@ -4135,18 +4237,7 @@ no_hash_pointers [KNL,EARLY] - Force pointers printed to the console or buffers to be - unhashed. By default, when a pointer is printed via %p - format string, that pointer is "hashed", i.e. obscured - by hashing the pointer value. This is a security feature - that hides actual kernel addresses from unprivileged - users, but it also makes debugging the kernel more - difficult since unequal pointers can no longer be - compared. However, if this command-line option is - specified, then all normal pointers will have their true - value printed. This option should only be specified when - debugging the kernel. Please do not use on production - kernels. + Alias for "hash_pointers=never". nohibernate [HIBERNATION] Disable hibernation and resume. @@ -4498,7 +4589,7 @@ bit 2: print timer info bit 3: print locks info if CONFIG_LOCKDEP is on bit 4: print ftrace buffer - bit 5: print all printk messages in buffer + bit 5: replay all messages on consoles at the end of panic bit 6: print all CPUs backtrace (if available in the arch) bit 7: print only tasks in uninterruptible (blocked) state *Be aware* that this option may print a _lot_ of lines, @@ -4506,6 +4597,25 @@ Use this option carefully, maybe worth to setup a bigger log buffer with "log_buf_len" along with this. + panic_sys_info= A comma separated list of extra information to be dumped + on panic. + Format: val[,val...] + Where @val can be any of the following: + + tasks: print all tasks info + mem: print system memory info + timers: print timers info + locks: print locks info if CONFIG_LOCKDEP is on + ftrace: print ftrace buffer + all_bt: print all CPUs backtrace (if available in the arch) + blocked_tasks: print only tasks in uninterruptible (blocked) state + + This is a human readable alternative to the 'panic_print' option. + + panic_console_replay + When panic happens, replay all kernel messages on + consoles at the end of panic. + parkbd.port= [HW] Parallel port number the keyboard adapter is connected to, default is 0. Format: <parport#> @@ -4965,6 +5075,18 @@ that number, otherwise (e.g., 'pmu_override=on'), MMCR1 remains 0. + pm_async= [PM] + Format: off + This parameter sets the initial value of the + /sys/power/pm_async sysfs knob at boot time. + If set to "off", disables asynchronous suspend and + resume of devices during system-wide power transitions. + This can be useful on platforms where device + dependencies are not well-defined, or for debugging + power management issues. Asynchronous operations are + enabled by default. + + pm_debug_messages [SUSPEND,KNL] Enable suspend/resume debug messages during boot up. @@ -5450,7 +5572,8 @@ echo 1 > /sys/module/rcutree/parameters/rcu_normal_wake_from_gp or pass a boot parameter "rcutree.rcu_normal_wake_from_gp=1" - Default is 0. + Default is 1 if num_possible_cpus() <= 16 and it is not explicitly + disabled by the boot parameter passing 0. rcuscale.gp_async= [KNL] Measure performance of asynchronous @@ -5672,6 +5795,31 @@ are zero, rcutorture acts as if is interpreted they are all non-zero. + rcutorture.gpwrap_lag= [KNL] + Enable grace-period wrap lag testing. Setting + to false prevents the gpwrap lag test from + running. Default is true. + + rcutorture.gpwrap_lag_gps= [KNL] + Set the value for grace-period wrap lag during + active lag testing periods. This controls how many + grace periods differences we tolerate between + rdp and rnp's gp_seq before setting overflow flag. + The default is always set to 8. + + rcutorture.gpwrap_lag_cycle_mins= [KNL] + Set the total cycle duration for gpwrap lag + testing in minutes. This is the total time for + one complete cycle of active and inactive + testing periods. Default is 30 minutes. + + rcutorture.gpwrap_lag_active_mins= [KNL] + Set the duration for which gpwrap lag is active + within each cycle, in minutes. During this time, + the grace-period wrap lag will be set to the + value specified by gpwrap_lag_gps. Default is + 5 minutes. + rcutorture.irqreader= [KNL] Run RCU readers from irq handlers, or, more accurately, from a timer handler. Not all RCU @@ -6268,7 +6416,7 @@ port and the regular usb controller gets disabled. root= [KNL] Root filesystem - Usually this a a block device specifier of some kind, + Usually this is 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 @@ -6295,6 +6443,11 @@ Memory area to be used by remote processor image, managed by CMA. + rt_group_sched= [KNL] Enable or disable SCHED_RR/FIFO group scheduling + when CONFIG_RT_GROUP_SCHED=y. Defaults to + !CONFIG_RT_GROUP_SCHED_DEFAULT_DISABLED. + Format: <bool> + rw [KNL] Mount root device read-write on boot S [KNL] Run init in single mode @@ -6322,6 +6475,11 @@ sa1100ir [NET] See drivers/net/irda/sa1100_ir.c. + sched_proxy_exec= [KNL] + Enables or disables "proxy execution" style + solution to mutex-based priority inversion. + Format: <bool> + sched_verbose [KNL,EARLY] Enables verbose scheduler debug messages. schedstats= [KNL,X86] Enable or disable scheduled statistics. @@ -6493,14 +6651,18 @@ slab_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/mm/slub.rst. + Documentation/admin-guide/mm/slab.rst. (slub_debug legacy name also accepted for now) + Using this option implies the "no_hash_pointers" + option which can be undone by adding the + "hash_pointers=always" option. + slab_max_order= [MM] Determines the maximum allowed order for slabs. A high setting may cause OOMs due to memory fragmentation. For more information see - Documentation/mm/slub.rst. + Documentation/admin-guide/mm/slab.rst. (slub_max_order legacy name also accepted for now) slab_merge [MM] @@ -6515,13 +6677,14 @@ 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/mm/slub.rst. + For more information see + Documentation/admin-guide/mm/slab.rst. (slub_min_objects legacy name also accepted for now) slab_min_order= [MM] Determines the minimum page order for slabs. Must be lower or equal to slab_max_order. For more information see - Documentation/mm/slub.rst. + Documentation/admin-guide/mm/slab.rst. (slub_min_order legacy name also accepted for now) slab_nomerge [MM] @@ -6535,7 +6698,8 @@ cache (risks via metadata attacks are mostly unchanged). Debug options disable merging on their own. - For more information see Documentation/mm/slub.rst. + For more information see + Documentation/admin-guide/mm/slab.rst. (slub_nomerge legacy name also accepted for now) slab_strict_numa [MM] @@ -6923,6 +7087,11 @@ consumed by the stack hash table. By default this is set to false. + stack_depot_max_pools= [KNL,EARLY] + Specify the maximum number of pools to use for storing + stack traces. Pools are allocated on-demand up to this + limit. Default value is 8191 pools. + stacktrace [FTRACE] Enabled the stack tracer on boot up. @@ -7149,6 +7318,14 @@ causing a major performance hit, and the space where machines are deployed is by other means guarded. + tpm_crb_ffa.busy_timeout_ms= [ARM64,TPM] + Maximum time in milliseconds to retry sending a message + to the TPM service before giving up. This parameter controls + how long the system will continue retrying when the TPM + service is busy. + Format: <unsigned int> + Default: 2000 (2 seconds) + tpm_suspend_pcr=[HW,TPM] Format: integer pcr id Specify that at suspend time, the tpm driver @@ -7423,6 +7600,19 @@ having this key zero'ed is acceptable. E.g. in testing scenarios. + tsa= [X86] Control mitigation for Transient Scheduler + Attacks on AMD CPUs. Search the following in your + favourite search engine for more details: + + "Technical guidance for mitigating transient scheduler + attacks". + + off - disable the mitigation + on - enable the mitigation (default) + user - mitigate only user/kernel transitions + vm - mitigate only guest/host transitions + + tsc= Disable clocksource stability checks for TSC. Format: <string> [x86] reliable: mark tsc clocksource as reliable, this |