--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+AMD64 Specific Boot Options
+===========================
+
+There are many others (usually documented in driver documentation), but
+only the AMD64 specific ones are listed here.
+
+Machine check
+=============
+Please see Documentation/x86/x86_64/machinecheck for sysfs runtime tunables.
+
+ mce=off
+ Disable machine check
+ mce=no_cmci
+ Disable CMCI(Corrected Machine Check Interrupt) that
+ Intel processor supports. Usually this disablement is
+ not recommended, but it might be handy if your hardware
+ is misbehaving.
+ Note that you'll get more problems without CMCI than with
+ due to the shared banks, i.e. you might get duplicated
+ error logs.
+ mce=dont_log_ce
+ Don't make logs for corrected errors. All events reported
+ as corrected are silently cleared by OS.
+ This option will be useful if you have no interest in any
+ of corrected errors.
+ mce=ignore_ce
+ Disable features for corrected errors, e.g. polling timer
+ and CMCI. All events reported as corrected are not cleared
+ by OS and remained in its error banks.
+ Usually this disablement is not recommended, however if
+ there is an agent checking/clearing corrected errors
+ (e.g. BIOS or hardware monitoring applications), conflicting
+ with OS's error handling, and you cannot deactivate the agent,
+ then this option will be a help.
+ mce=no_lmce
+ Do not opt-in to Local MCE delivery. Use legacy method
+ to broadcast MCEs.
+ mce=bootlog
+ Enable logging of machine checks left over from booting.
+ Disabled by default on AMD Fam10h and older because some BIOS
+ leave bogus ones.
+ If your BIOS doesn't do that it's a good idea to enable though
+ to make sure you log even machine check events that result
+ in a reboot. On Intel systems it is enabled by default.
+ mce=nobootlog
+ Disable boot machine check logging.
+ mce=tolerancelevel[,monarchtimeout] (number,number)
+ tolerance levels:
+ 0: always panic on uncorrected errors, log corrected errors
+ 1: panic or SIGBUS on uncorrected errors, log corrected errors
+ 2: SIGBUS or log uncorrected errors, log corrected errors
+ 3: never panic or SIGBUS, log all errors (for testing only)
+ Default is 1
+ Can be also set using sysfs which is preferable.
+ monarchtimeout:
+ Sets the time in us to wait for other CPUs on machine checks. 0
+ to disable.
+ mce=bios_cmci_threshold
+ Don't overwrite the bios-set CMCI threshold. This boot option
+ prevents Linux from overwriting the CMCI threshold set by the
+ bios. Without this option, Linux always sets the CMCI
+ threshold to 1. Enabling this may make memory predictive failure
+ analysis less effective if the bios sets thresholds for memory
+ errors since we will not see details for all errors.
+ mce=recovery
+ Force-enable recoverable machine check code paths
+
+ nomce (for compatibility with i386)
+ same as mce=off
+
+ Everything else is in sysfs now.
+
+APICs
+=====
+
+ apic
+ Use IO-APIC. Default
+
+ noapic
+ Don't use the IO-APIC.
+
+ disableapic
+ Don't use the local APIC
+
+ nolapic
+ Don't use the local APIC (alias for i386 compatibility)
+
+ pirq=...
+ See Documentation/x86/i386/IO-APIC.txt
+
+ noapictimer
+ Don't set up the APIC timer
+
+ no_timer_check
+ Don't check the IO-APIC timer. This can work around
+ problems with incorrect timer initialization on some boards.
+
+ apicpmtimer
+ Do APIC timer calibration using the pmtimer. Implies
+ apicmaintimer. Useful when your PIT timer is totally broken.
+
+Timing
+======
+
+ notsc
+ Deprecated, use tsc=unstable instead.
+
+ nohpet
+ Don't use the HPET timer.
+
+Idle loop
+=========
+
+ idle=poll
+ Don't do power saving in the idle loop using HLT, but poll for rescheduling
+ event. This will make the CPUs eat a lot more power, but may be useful
+ to get slightly better performance in multiprocessor benchmarks. It also
+ makes some profiling using performance counters more accurate.
+ Please note that on systems with MONITOR/MWAIT support (like Intel EM64T
+ CPUs) this option has no performance advantage over the normal idle loop.
+ It may also interact badly with hyperthreading.
+
+Rebooting
+=========
+
+ reboot=b[ios] | t[riple] | k[bd] | a[cpi] | e[fi] [, [w]arm | [c]old]
+ bios
+ Use the CPU reboot vector for warm reset
+ warm
+ Don't set the cold reboot flag
+ cold
+ Set the cold reboot flag
+ triple
+ Force a triple fault (init)
+ kbd
+ Use the keyboard controller. cold reset (default)
+ acpi
+ Use the ACPI RESET_REG in the FADT. If ACPI is not configured or
+ the ACPI reset does not work, the reboot path attempts the reset
+ using the keyboard controller.
+ efi
+ Use efi reset_system runtime service. If EFI is not configured or
+ the EFI reset does not work, the reboot path attempts the reset using
+ the keyboard controller.
+
+ Using warm reset will be much faster especially on big memory
+ systems because the BIOS will not go through the memory check.
+ Disadvantage is that not all hardware will be completely reinitialized
+ on reboot so there may be boot problems on some systems.
+
+ reboot=force
+ Don't stop other CPUs on reboot. This can make reboot more reliable
+ in some cases.
+
+Non Executable Mappings
+=======================
+
+ noexec=on|off
+ on
+ Enable(default)
+ off
+ Disable
+
+NUMA
+====
+
+ numa=off
+ Only set up a single NUMA node spanning all memory.
+
+ numa=noacpi
+ Don't parse the SRAT table for NUMA setup
+
+ numa=fake=<size>[MG]
+ If given as a memory unit, fills all system RAM with nodes of
+ size interleaved over physical nodes.
+
+ numa=fake=<N>
+ If given as an integer, fills all system RAM with N fake nodes
+ interleaved over physical nodes.
+
+ numa=fake=<N>U
+ If given as an integer followed by 'U', it will divide each
+ physical node into N emulated nodes.
+
+ACPI
+====
+
+ acpi=off
+ Don't enable ACPI
+ acpi=ht
+ Use ACPI boot table parsing, but don't enable ACPI interpreter
+ acpi=force
+ Force ACPI on (currently not needed)
+ acpi=strict
+ Disable out of spec ACPI workarounds.
+ acpi_sci={edge,level,high,low}
+ Set up ACPI SCI interrupt.
+ acpi=noirq
+ Don't route interrupts
+ acpi=nocmcff
+ Disable firmware first mode for corrected errors. This
+ disables parsing the HEST CMC error source to check if
+ firmware has set the FF flag. This may result in
+ duplicate corrected error reports.
+
+PCI
+===
+
+ pci=off
+ Don't use PCI
+ pci=conf1
+ Use conf1 access.
+ pci=conf2
+ Use conf2 access.
+ pci=rom
+ Assign ROMs.
+ pci=assign-busses
+ Assign busses
+ pci=irqmask=MASK
+ Set PCI interrupt mask to MASK
+ pci=lastbus=NUMBER
+ Scan up to NUMBER busses, no matter what the mptable says.
+ pci=noacpi
+ Don't use ACPI to set up PCI interrupt routing.
+
+IOMMU (input/output memory management unit)
+===========================================
+Multiple x86-64 PCI-DMA mapping implementations exist, for example:
+
+ 1. <lib/dma-direct.c>: use no hardware/software IOMMU at all
+ (e.g. because you have < 3 GB memory).
+ Kernel boot message: "PCI-DMA: Disabling IOMMU"
+
+ 2. <arch/x86/kernel/amd_gart_64.c>: AMD GART based hardware IOMMU.
+ Kernel boot message: "PCI-DMA: using GART IOMMU"
+
+ 3. <arch/x86_64/kernel/pci-swiotlb.c> : Software IOMMU implementation. Used
+ e.g. if there is no hardware IOMMU in the system and it is need because
+ you have >3GB memory or told the kernel to us it (iommu=soft))
+ Kernel boot message: "PCI-DMA: Using software bounce buffering
+ for IO (SWIOTLB)"
+
+ 4. <arch/x86_64/pci-calgary.c> : IBM Calgary hardware IOMMU. Used in IBM
+ pSeries and xSeries servers. This hardware IOMMU supports DMA address
+ mapping with memory protection, etc.
+ Kernel boot message: "PCI-DMA: Using Calgary IOMMU"
+
+::
+
+ iommu=[<size>][,noagp][,off][,force][,noforce]
+ [,memaper[=<order>]][,merge][,fullflush][,nomerge]
+ [,noaperture][,calgary]
+
+General iommu options:
+
+ off
+ Don't initialize and use any kind of IOMMU.
+ noforce
+ Don't force hardware IOMMU usage when it is not needed. (default).
+ force
+ Force the use of the hardware IOMMU even when it is
+ not actually needed (e.g. because < 3 GB memory).
+ soft
+ Use software bounce buffering (SWIOTLB) (default for
+ Intel machines). This can be used to prevent the usage
+ of an available hardware IOMMU.
+
+iommu options only relevant to the AMD GART hardware IOMMU:
+
+ <size>
+ Set the size of the remapping area in bytes.
+ allowed
+ Overwrite iommu off workarounds for specific chipsets.
+ fullflush
+ Flush IOMMU on each allocation (default).
+ nofullflush
+ Don't use IOMMU fullflush.
+ memaper[=<order>]
+ Allocate an own aperture over RAM with size 32MB<<order.
+ (default: order=1, i.e. 64MB)
+ merge
+ Do scatter-gather (SG) merging. Implies "force" (experimental).
+ nomerge
+ Don't do scatter-gather (SG) merging.
+ noaperture
+ Ask the IOMMU not to touch the aperture for AGP.
+ noagp
+ Don't initialize the AGP driver and use full aperture.
+ panic
+ Always panic when IOMMU overflows.
+ calgary
+ Use the Calgary IOMMU if it is available
+
+iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU
+implementation:
+
+ swiotlb=<pages>[,force]
+ <pages>
+ Prereserve that many 128K pages for the software IO bounce buffering.
+ force
+ Force all IO through the software TLB.
+
+Settings for the IBM Calgary hardware IOMMU currently found in IBM
+pSeries and xSeries machines
+
+ calgary=[64k,128k,256k,512k,1M,2M,4M,8M]
+ Set the size of each PCI slot's translation table when using the
+ Calgary IOMMU. This is the size of the translation table itself
+ in main memory. The smallest table, 64k, covers an IO space of
+ 32MB; the largest, 8MB table, can cover an IO space of 4GB.
+ Normally the kernel will make the right choice by itself.
+ calgary=[translate_empty_slots]
+ Enable translation even on slots that have no devices attached to
+ them, in case a device will be hotplugged in the future.
+ calgary=[disable=<PCI bus number>]
+ Disable translation on a given PHB. For
+ example, the built-in graphics adapter resides on the first bridge
+ (PCI bus number 0); if translation (isolation) is enabled on this
+ bridge, X servers that access the hardware directly from user
+ space might stop working. Use this option if you have devices that
+ are accessed from userspace directly on some PCI host bridge.
+ panic
+ Always panic when IOMMU overflows
+
+
+Miscellaneous
+=============
+
+ nogbpages
+ Do not use GB pages for kernel direct mappings.
+ gbpages
+ Use GB pages for kernel direct mappings.
+++ /dev/null
-AMD64 specific boot options
-
-There are many others (usually documented in driver documentation), but
-only the AMD64 specific ones are listed here.
-
-Machine check
-
- Please see Documentation/x86/x86_64/machinecheck for sysfs runtime tunables.
-
- mce=off
- Disable machine check
- mce=no_cmci
- Disable CMCI(Corrected Machine Check Interrupt) that
- Intel processor supports. Usually this disablement is
- not recommended, but it might be handy if your hardware
- is misbehaving.
- Note that you'll get more problems without CMCI than with
- due to the shared banks, i.e. you might get duplicated
- error logs.
- mce=dont_log_ce
- Don't make logs for corrected errors. All events reported
- as corrected are silently cleared by OS.
- This option will be useful if you have no interest in any
- of corrected errors.
- mce=ignore_ce
- Disable features for corrected errors, e.g. polling timer
- and CMCI. All events reported as corrected are not cleared
- by OS and remained in its error banks.
- Usually this disablement is not recommended, however if
- there is an agent checking/clearing corrected errors
- (e.g. BIOS or hardware monitoring applications), conflicting
- with OS's error handling, and you cannot deactivate the agent,
- then this option will be a help.
- mce=no_lmce
- Do not opt-in to Local MCE delivery. Use legacy method
- to broadcast MCEs.
- mce=bootlog
- Enable logging of machine checks left over from booting.
- Disabled by default on AMD Fam10h and older because some BIOS
- leave bogus ones.
- If your BIOS doesn't do that it's a good idea to enable though
- to make sure you log even machine check events that result
- in a reboot. On Intel systems it is enabled by default.
- mce=nobootlog
- Disable boot machine check logging.
- mce=tolerancelevel[,monarchtimeout] (number,number)
- tolerance levels:
- 0: always panic on uncorrected errors, log corrected errors
- 1: panic or SIGBUS on uncorrected errors, log corrected errors
- 2: SIGBUS or log uncorrected errors, log corrected errors
- 3: never panic or SIGBUS, log all errors (for testing only)
- Default is 1
- Can be also set using sysfs which is preferable.
- monarchtimeout:
- Sets the time in us to wait for other CPUs on machine checks. 0
- to disable.
- mce=bios_cmci_threshold
- Don't overwrite the bios-set CMCI threshold. This boot option
- prevents Linux from overwriting the CMCI threshold set by the
- bios. Without this option, Linux always sets the CMCI
- threshold to 1. Enabling this may make memory predictive failure
- analysis less effective if the bios sets thresholds for memory
- errors since we will not see details for all errors.
- mce=recovery
- Force-enable recoverable machine check code paths
-
- nomce (for compatibility with i386): same as mce=off
-
- Everything else is in sysfs now.
-
-APICs
-
- apic Use IO-APIC. Default
-
- noapic Don't use the IO-APIC.
-
- disableapic Don't use the local APIC
-
- nolapic Don't use the local APIC (alias for i386 compatibility)
-
- pirq=... See Documentation/x86/i386/IO-APIC.txt
-
- noapictimer Don't set up the APIC timer
-
- no_timer_check Don't check the IO-APIC timer. This can work around
- problems with incorrect timer initialization on some boards.
- apicpmtimer
- Do APIC timer calibration using the pmtimer. Implies
- apicmaintimer. Useful when your PIT timer is totally
- broken.
-
-Timing
-
- notsc
- Deprecated, use tsc=unstable instead.
-
- nohpet
- Don't use the HPET timer.
-
-Idle loop
-
- idle=poll
- Don't do power saving in the idle loop using HLT, but poll for rescheduling
- event. This will make the CPUs eat a lot more power, but may be useful
- to get slightly better performance in multiprocessor benchmarks. It also
- makes some profiling using performance counters more accurate.
- Please note that on systems with MONITOR/MWAIT support (like Intel EM64T
- CPUs) this option has no performance advantage over the normal idle loop.
- It may also interact badly with hyperthreading.
-
-Rebooting
-
- reboot=b[ios] | t[riple] | k[bd] | a[cpi] | e[fi] [, [w]arm | [c]old]
- bios Use the CPU reboot vector for warm reset
- warm Don't set the cold reboot flag
- cold Set the cold reboot flag
- triple Force a triple fault (init)
- kbd Use the keyboard controller. cold reset (default)
- acpi Use the ACPI RESET_REG in the FADT. If ACPI is not configured or the
- ACPI reset does not work, the reboot path attempts the reset using
- the keyboard controller.
- efi Use efi reset_system runtime service. If EFI is not configured or the
- EFI reset does not work, the reboot path attempts the reset using
- the keyboard controller.
-
- Using warm reset will be much faster especially on big memory
- systems because the BIOS will not go through the memory check.
- Disadvantage is that not all hardware will be completely reinitialized
- on reboot so there may be boot problems on some systems.
-
- reboot=force
-
- Don't stop other CPUs on reboot. This can make reboot more reliable
- in some cases.
-
-Non Executable Mappings
-
- noexec=on|off
-
- on Enable(default)
- off Disable
-
-NUMA
-
- numa=off Only set up a single NUMA node spanning all memory.
-
- numa=noacpi Don't parse the SRAT table for NUMA setup
-
- numa=fake=<size>[MG]
- If given as a memory unit, fills all system RAM with nodes of
- size interleaved over physical nodes.
-
- numa=fake=<N>
- If given as an integer, fills all system RAM with N fake nodes
- interleaved over physical nodes.
-
- numa=fake=<N>U
- If given as an integer followed by 'U', it will divide each
- physical node into N emulated nodes.
-
-ACPI
-
- acpi=off Don't enable ACPI
- acpi=ht Use ACPI boot table parsing, but don't enable ACPI
- interpreter
- acpi=force Force ACPI on (currently not needed)
-
- acpi=strict Disable out of spec ACPI workarounds.
-
- acpi_sci={edge,level,high,low} Set up ACPI SCI interrupt.
-
- acpi=noirq Don't route interrupts
-
- acpi=nocmcff Disable firmware first mode for corrected errors. This
- disables parsing the HEST CMC error source to check if
- firmware has set the FF flag. This may result in
- duplicate corrected error reports.
-
-PCI
-
- pci=off Don't use PCI
- pci=conf1 Use conf1 access.
- pci=conf2 Use conf2 access.
- pci=rom Assign ROMs.
- pci=assign-busses Assign busses
- pci=irqmask=MASK Set PCI interrupt mask to MASK
- pci=lastbus=NUMBER Scan up to NUMBER busses, no matter what the mptable says.
- pci=noacpi Don't use ACPI to set up PCI interrupt routing.
-
-IOMMU (input/output memory management unit)
-
- Multiple x86-64 PCI-DMA mapping implementations exist, for example:
-
- 1. <lib/dma-direct.c>: use no hardware/software IOMMU at all
- (e.g. because you have < 3 GB memory).
- Kernel boot message: "PCI-DMA: Disabling IOMMU"
-
- 2. <arch/x86/kernel/amd_gart_64.c>: AMD GART based hardware IOMMU.
- Kernel boot message: "PCI-DMA: using GART IOMMU"
-
- 3. <arch/x86_64/kernel/pci-swiotlb.c> : Software IOMMU implementation. Used
- e.g. if there is no hardware IOMMU in the system and it is need because
- you have >3GB memory or told the kernel to us it (iommu=soft))
- Kernel boot message: "PCI-DMA: Using software bounce buffering
- for IO (SWIOTLB)"
-
- 4. <arch/x86_64/pci-calgary.c> : IBM Calgary hardware IOMMU. Used in IBM
- pSeries and xSeries servers. This hardware IOMMU supports DMA address
- mapping with memory protection, etc.
- Kernel boot message: "PCI-DMA: Using Calgary IOMMU"
-
- iommu=[<size>][,noagp][,off][,force][,noforce]
- [,memaper[=<order>]][,merge][,fullflush][,nomerge]
- [,noaperture][,calgary]
-
- General iommu options:
- off Don't initialize and use any kind of IOMMU.
- noforce Don't force hardware IOMMU usage when it is not needed.
- (default).
- force Force the use of the hardware IOMMU even when it is
- not actually needed (e.g. because < 3 GB memory).
- soft Use software bounce buffering (SWIOTLB) (default for
- Intel machines). This can be used to prevent the usage
- of an available hardware IOMMU.
-
- iommu options only relevant to the AMD GART hardware IOMMU:
- <size> Set the size of the remapping area in bytes.
- allowed Overwrite iommu off workarounds for specific chipsets.
- fullflush Flush IOMMU on each allocation (default).
- nofullflush Don't use IOMMU fullflush.
- memaper[=<order>] Allocate an own aperture over RAM with size 32MB<<order.
- (default: order=1, i.e. 64MB)
- merge Do scatter-gather (SG) merging. Implies "force"
- (experimental).
- nomerge Don't do scatter-gather (SG) merging.
- noaperture Ask the IOMMU not to touch the aperture for AGP.
- noagp Don't initialize the AGP driver and use full aperture.
- panic Always panic when IOMMU overflows.
- calgary Use the Calgary IOMMU if it is available
-
- iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU
- implementation:
- swiotlb=<pages>[,force]
- <pages> Prereserve that many 128K pages for the software IO
- bounce buffering.
- force Force all IO through the software TLB.
-
- Settings for the IBM Calgary hardware IOMMU currently found in IBM
- pSeries and xSeries machines:
-
- calgary=[64k,128k,256k,512k,1M,2M,4M,8M]
- calgary=[translate_empty_slots]
- calgary=[disable=<PCI bus number>]
- panic Always panic when IOMMU overflows
-
- 64k,...,8M - Set the size of each PCI slot's translation table
- when using the Calgary IOMMU. This is the size of the translation
- table itself in main memory. The smallest table, 64k, covers an IO
- space of 32MB; the largest, 8MB table, can cover an IO space of
- 4GB. Normally the kernel will make the right choice by itself.
-
- translate_empty_slots - Enable translation even on slots that have
- no devices attached to them, in case a device will be hotplugged
- in the future.
-
- disable=<PCI bus number> - Disable translation on a given PHB. For
- example, the built-in graphics adapter resides on the first bridge
- (PCI bus number 0); if translation (isolation) is enabled on this
- bridge, X servers that access the hardware directly from user
- space might stop working. Use this option if you have devices that
- are accessed from userspace directly on some PCI host bridge.
-
-Miscellaneous
-
- nogbpages
- Do not use GB pages for kernel direct mappings.
- gbpages
- Use GB pages for kernel direct mappings.
projects / linux-2.6-microblaze.git / commitdiff