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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2015-07-20 10:08:17 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2015-07-20 10:08:17 -0700
commitc57d5621d2f2dc238f4b9c4d00b2a54187a75445 (patch)
treeece13738a44545fb110e5d73adbf2625bc7a1ea6 /Documentation/kernel-parameters.txt
parent6ccfe64c770139675a080ee5029ded7d89d9ea0d (diff)
parent52721d9d3334c1cb1f76219a161084094ec634dc (diff)
Merge tag 'v4.2-rc3' into next
Sync up with Linux 4.2-rc3 to bring in infrastructure (OF) pieces.
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt219
1 files changed, 163 insertions, 56 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index fd0f7cd8e496..d74bceaa4cbc 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -165,7 +165,7 @@ multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
bytes respectively. Such letter suffixes can also be entirely omitted.
- acpi= [HW,ACPI,X86]
+ acpi= [HW,ACPI,X86,ARM64]
Advanced Configuration and Power Interface
Format: { force | off | strict | noirq | rsdt }
force -- enable ACPI if default was off
@@ -175,14 +175,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
strictly ACPI specification compliant.
rsdt -- prefer RSDT over (default) XSDT
copy_dsdt -- copy DSDT to memory
+ For ARM64, ONLY "acpi=off" or "acpi=force" are available
See also Documentation/power/runtime_pm.txt, pci=noacpi
- acpi_rsdp= [ACPI,EFI,KEXEC]
- Pass the RSDP address to the kernel, mostly used
- on machines running EFI runtime service to boot the
- second kernel for kdump.
-
acpi_apic_instance= [ACPI, IOAPIC]
Format: <int>
2: use 2nd APIC table, if available
@@ -196,6 +192,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
(e.g. thinkpad_acpi, sony_acpi, etc.) instead
of the ACPI video.ko driver.
+ acpica_no_return_repair [HW, ACPI]
+ Disable AML predefined validation mechanism
+ This mechanism can repair the evaluation result to make
+ the return objects more ACPI specification compliant.
+ This option is useful for developers to identify the
+ root cause of an AML interpreter issue when the issue
+ has something to do with the repair mechanism.
+
acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Format: <int>
@@ -224,6 +228,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
unusable. The "log_buf_len" parameter may be useful
if you need to capture more output.
+ acpi_enforce_resources= [ACPI]
+ { strict | lax | no }
+ Check for resource conflicts between native drivers
+ and ACPI OperationRegions (SystemIO and SystemMemory
+ only). IO ports and memory declared in ACPI might be
+ used by the ACPI subsystem in arbitrary AML code and
+ can interfere with legacy drivers.
+ strict (default): access to resources claimed by ACPI
+ is denied; legacy drivers trying to access reserved
+ resources will fail to bind to device using them.
+ lax: access to resources claimed by ACPI is allowed;
+ legacy drivers trying to access reserved resources
+ will bind successfully but a warning message is logged.
+ no: ACPI OperationRegions are not marked as reserved,
+ no further checks are performed.
+
acpi_force_table_verification [HW,ACPI]
Enable table checksum verification during early stage.
By default, this is disabled due to x86 early mapping
@@ -252,6 +272,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
This feature is enabled by default.
This option allows to turn off the feature.
+ acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
+ kernels.
+
acpi_no_static_ssdt [HW,ACPI]
Disable installation of static SSDTs at early boot time
By default, SSDTs contained in the RSDT/XSDT will be
@@ -262,17 +285,20 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
dynamic table installation which will install SSDT
tables to /sys/firmware/acpi/tables/dynamic.
- acpica_no_return_repair [HW, ACPI]
- Disable AML predefined validation mechanism
- This mechanism can repair the evaluation result to make
- the return objects more ACPI specification compliant.
- This option is useful for developers to identify the
- root cause of an AML interpreter issue when the issue
- has something to do with the repair mechanism.
+ acpi_rsdp= [ACPI,EFI,KEXEC]
+ Pass the RSDP address to the kernel, mostly used
+ on machines running EFI runtime service to boot the
+ second kernel for kdump.
acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
Format: To spoof as Windows 98: ="Microsoft Windows"
+ acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
+ of 2 which is mandated by ACPI 6) as the supported ACPI
+ specification revision (when using this switch, it may
+ be necessary to carry out a cold reboot _twice_ in a
+ row to make it take effect on the platform firmware).
+
acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
acpi_osi="string1" # add string1
acpi_osi="!string2" # remove string2
@@ -364,25 +390,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Use timer override. For some broken Nvidia NF5 boards
that require a timer override, but don't have HPET
- acpi_enforce_resources= [ACPI]
- { strict | lax | no }
- Check for resource conflicts between native drivers
- and ACPI OperationRegions (SystemIO and SystemMemory
- only). IO ports and memory declared in ACPI might be
- used by the ACPI subsystem in arbitrary AML code and
- can interfere with legacy drivers.
- strict (default): access to resources claimed by ACPI
- is denied; legacy drivers trying to access reserved
- resources will fail to bind to device using them.
- lax: access to resources claimed by ACPI is allowed;
- legacy drivers trying to access reserved resources
- will bind successfully but a warning message is logged.
- no: ACPI OperationRegions are not marked as reserved,
- no further checks are performed.
-
- acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
- kernels.
-
add_efi_memmap [EFI; X86] Include EFI memory map in
kernel's map of available physical RAM.
@@ -713,10 +720,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
+ uart[8250],mmio32,<addr>[,options]
+ uart[8250],0x<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address,
- switching to the matching ttyS device later. The
- options are the same as for ttyS, above.
+ switching to the matching ttyS device later.
+ MMIO inter-register address stride is either 8-bit
+ (mmio) or 32-bit (mmio32).
+ If none of [io|mmio|mmio32], <addr> is assumed to be
+ equivalent to 'mmio'. 'options' are specified in the
+ same format described for ttyS above; if unspecified,
+ the h/w is not re-initialized.
+
hvc<n> Use the hypervisor console device <n>. This is for
both Xen and PowerPC hypervisors.
@@ -737,6 +752,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
cpuidle.off=1 [CPU_IDLE]
disable the cpuidle sub-system
+ cpu_init_udelay=N
+ [X86] Delay for N microsec between assert and de-assert
+ of APIC INIT to start processors. This delay occurs
+ on every CPU online, such as boot, and resume from suspend.
+ Default: 10000
+
cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Format:
<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
@@ -928,6 +949,19 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Enable debug messages at boot time. See
Documentation/dynamic-debug-howto.txt for details.
+ nompx [X86] Disables Intel Memory Protection Extensions.
+ See Documentation/x86/intel_mpx.txt for more
+ information about the feature.
+
+ eagerfpu= [X86]
+ on enable eager fpu restore
+ off disable eager fpu restore
+ auto selects the default scheme, which automatically
+ enables eagerfpu restore for xsaveopt.
+
+ module.async_probe [KNL]
+ Enable asynchronous probe on this module.
+
early_ioremap_debug [KNL]
Enable debug messages in early_ioremap support. This
is useful for tracking down temporary early mappings
@@ -944,11 +978,16 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
uart[8250],mmio32,<addr>[,options]
+ uart[8250],mmio32be,<addr>[,options]
+ uart[8250],0x<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address.
MMIO inter-register address stride is either 8-bit
- (mmio) or 32-bit (mmio32).
- The options are the same as for ttyS, above.
+ (mmio) or 32-bit (mmio32 or mmio32be).
+ If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
+ to be equivalent to 'mmio'. 'options' are specified
+ in the same format described for "console=ttyS<n>"; if
+ unspecified, the h/w is not initialized.
pl011,<addr>
Start an early, polled-mode console on a pl011 serial
@@ -990,6 +1029,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
earlyprintk=serial[,0x...[,baudrate]]
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
+ earlyprintk=pciserial,bus:device.function[,baudrate]
earlyprintk is useful when the kernel crashes before
the normal console is initialized. It is not enabled by
@@ -1036,7 +1076,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Format: {"off" | "on" | "skip[mbr]"}
efi= [EFI]
- Format: { "old_map", "nochunk", "noruntime" }
+ Format: { "old_map", "nochunk", "noruntime", "debug" }
old_map [X86-64]: switch to the old ioremap-based EFI
runtime services mapping. 32-bit still uses this one by
default.
@@ -1044,6 +1084,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
boot stub, as chunking can cause problems with some
firmware implementations.
noruntime : disable EFI runtime services support
+ debug: enable misc debug output
efi_no_storage_paranoia [EFI; X86]
Using this parameter you can use more than 50% of
@@ -1382,7 +1423,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
The list of supported hash algorithms is defined
in crypto/hash_info.h.
- ima_tcb [IMA]
+ ima_policy= [IMA]
+ The builtin measurement policy to load during IMA
+ setup. Specyfing "tcb" as the value, measures all
+ programs exec'd, files mmap'd for exec, and all files
+ opened with the read mode bit set by either the
+ effective uid (euid=0) or uid=0.
+ Format: "tcb"
+
+ ima_tcb [IMA] Deprecated. Use ima_policy= instead.
Load a policy which meets the needs of the Trusted
Computing Base. This means IMA will measure all
programs exec'd, files mmap'd for exec, and all files
@@ -1390,7 +1439,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
ima_template= [IMA]
Select one of defined IMA measurements template formats.
- Formats: { "ima" | "ima-ng" }
+ Formats: { "ima" | "ima-ng" | "ima-sig" }
Default: "ima-ng"
ima_template_fmt=
@@ -1465,6 +1514,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
By default, super page will be supported if Intel IOMMU
has the capability. With this option, super page will
not be supported.
+ ecs_off [Default Off]
+ By default, extended context tables will be supported if
+ the hardware advertises that it has support both for the
+ extended tables themselves, and also PASID support. With
+ this option set, extended tables will not be used even
+ on hardware which claims to support them.
intel_idle.max_cstate= [KNL,HW,ACPI,X86]
0 disables intel_idle and fall back on acpi_idle.
@@ -1758,6 +1813,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
* [no]ncq: Turn on or off NCQ.
+ * [no]ncqtrim: Turn off queued DSM TRIM.
+
* nohrst, nosrst, norst: suppress hard, soft
and both resets.
@@ -1969,6 +2026,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
or
memmap=0x10000$0x18690000
+ memmap=nn[KMG]!ss[KMG]
+ [KNL,X86] Mark specific memory as protected.
+ Region of memory to be used, from ss to ss+nn.
+ The memory region may be marked as e820 type 12 (0xc)
+ and is NVDIMM or ADR memory.
+
memory_corruption_check=0/1 [X86]
Some BIOSes seem to corrupt the first 64k of
memory when doing things like suspend/resume.
@@ -1992,7 +2055,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
seconds. Use this parameter to check at some
other rate. 0 disables periodic checking.
- memtest= [KNL,X86] Enable memtest
+ memtest= [KNL,X86,ARM] Enable memtest
Format: <integer>
default : 0 <disable>
Specifies the number of memtest passes to be
@@ -2239,8 +2302,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Format: [panic,][nopanic,][num]
- Valid num: 0
+ Valid num: 0 or 1
0 - turn nmi_watchdog off
+ 1 - turn nmi_watchdog on
When panic is specified, panic when an NMI watchdog
timeout occurs (or 'nopanic' to override the opposite
default).
@@ -2319,12 +2383,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
noexec32=off: disable non-executable mappings
read implies executable mappings
- nofpu [SH] Disable hardware FPU at boot time.
+ nofpu [MIPS,SH] Disable hardware FPU at boot time.
nofxsr [BUGS=X86-32] Disables x86 floating point extended
register save and restore. The kernel will only save
legacy floating-point registers on task switch.
+ nohugeiomap [KNL,x86] Disable kernel huge I/O mappings.
+
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.
@@ -2344,12 +2410,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
parameter, xsave area per process might occupy more
memory on xsaves enabled systems.
- eagerfpu= [X86]
- on enable eager fpu restore
- off disable eager fpu restore
- auto selects the default scheme, which automatically
- enables eagerfpu restore for xsaveopt.
-
nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
wfi(ARM) instruction doesn't work correctly and not to
use it. This is also useful when using JTAG debugger.
@@ -2418,7 +2478,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
nomca [IA-64] Disable machine check abort handling
- nomce [X86-32] Machine Check Exception
+ nomce [X86-32] Disable Machine Check Exception
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).
@@ -2467,7 +2527,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
nousb [USB] Disable the USB subsystem
- nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
+ nowatchdog [KNL] Disable both lockup detectors, i.e.
+ soft-lockup and NMI watchdog (hard-lockup).
nowb [ARM]
@@ -2972,6 +3033,35 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Set maximum number of finished RCU callbacks to
process in one batch.
+ rcutree.dump_tree= [KNL]
+ Dump the structure of the rcu_node combining tree
+ out at early boot. This is used for diagnostic
+ purposes, to verify correct tree setup.
+
+ rcutree.gp_cleanup_delay= [KNL]
+ Set the number of jiffies to delay each step of
+ RCU grace-period cleanup. This only has effect
+ when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set.
+
+ rcutree.gp_init_delay= [KNL]
+ Set the number of jiffies to delay each step of
+ RCU grace-period initialization. This only has
+ effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT
+ is set.
+
+ rcutree.gp_preinit_delay= [KNL]
+ Set the number of jiffies to delay each step of
+ RCU grace-period pre-initialization, that is,
+ the propagation of recent CPU-hotplug changes up
+ the rcu_node combining tree. This only has effect
+ when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set.
+
+ rcutree.rcu_fanout_exact= [KNL]
+ Disable autobalancing of the rcu_node combining
+ tree. This is used by rcutorture, and might
+ possibly be useful for architectures having high
+ cache-to-cache transfer latencies.
+
rcutree.rcu_fanout_leaf= [KNL]
Increase the number of CPUs assigned to each
leaf rcu_node structure. Useful for very large
@@ -2995,11 +3085,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
value is one, and maximum value is HZ.
rcutree.kthread_prio= [KNL,BOOT]
- Set the SCHED_FIFO priority of the RCU
- per-CPU kthreads (rcuc/N). This value is also
- used for the priority of the RCU boost threads
- (rcub/N). Valid values are 1-99 and the default
- is 1 (the least-favored priority).
+ Set the SCHED_FIFO priority of the RCU per-CPU
+ kthreads (rcuc/N). This value is also used for
+ the priority of the RCU boost threads (rcub/N)
+ and for the RCU grace-period kthreads (rcu_bh,
+ rcu_preempt, and rcu_sched). If RCU_BOOST is
+ set, valid values are 1-99 and the default is 1
+ (the least-favored priority). Otherwise, when
+ RCU_BOOST is not set, valid values are 0-99 and
+ the default is zero (non-realtime operation).
rcutree.rcu_nocb_leader_stride= [KNL]
Set the number of NOCB kthread groups, which
@@ -3071,7 +3165,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
test, hence the "fake".
rcutorture.nreaders= [KNL]
- Set number of RCU readers.
+ Set number of RCU readers. The value -1 selects
+ N-1, where N is the number of CPUs. A value
+ "n" less than -1 selects N-n-2, where N is again
+ the number of CPUs. For example, -2 selects N
+ (the number of CPUs), -3 selects N+1, and so on.
rcutorture.object_debug= [KNL]
Enable debug-object double-call_rcu() testing.
@@ -3466,6 +3564,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
improve throughput, but will also increase the
amount of memory reserved for use by the client.
+ suspend.pm_test_delay=
+ [SUSPEND]
+ Sets the number of seconds to remain in a suspend test
+ mode before resuming the system (see
+ /sys/power/pm_test). Only available when CONFIG_PM_DEBUG
+ is set. Default value is 5.
+
swapaccount=[0|1]
[KNL] Enable accounting of swap in memory resource
controller if no parameter or 1 is given or disable
@@ -3750,6 +3855,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
READ_CAPACITY_16 command);
f = NO_REPORT_OPCODES (don't use report opcodes
command, uas only);
+ g = MAX_SECTORS_240 (don't transfer more than
+ 240 sectors at a time, uas only);
h = CAPACITY_HEURISTICS (decrease the
reported device capacity by one
sector if the number is odd);

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