From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx>
Documentation/arch/x86/x86_64/boot-options.rst is causing unnecessary
confusion by being a second place where one can put x86 boot options.
Move them into the main one.
Drop removed ones like "acpi=ht", while at it.
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
---
.../admin-guide/kernel-parameters.rst | 3 -
.../admin-guide/kernel-parameters.txt | 214 ++++++++++--
.../arch/x86/x86_64/boot-options.rst | 312 ------------------
.../arch/x86/x86_64/fake-numa-for-cpusets.rst | 2 +-
arch/x86/Kconfig.debug | 2 +-
arch/x86/kernel/pci-dma.c | 4 -
6 files changed, 194 insertions(+), 343 deletions(-)
delete mode 100644 Documentation/arch/x86/x86_64/boot-options.rst
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst
index fdea7c26ef80..5f68b40247d4 100644
--- a/Documentation/admin-guide/kernel-parameters.rst
+++ b/Documentation/admin-guide/kernel-parameters.rst
@@ -178,8 +178,6 @@ is applicable::
WDT Watchdog support is enabled.
X86-32 X86-32, aka i386 architecture is enabled.
X86-64 X86-64 architecture is enabled.
- More X86-64 boot options can be found in
- Documentation/arch/x86/x86_64/boot-options.rst.
X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
X86_UV SGI UV support is enabled.
XEN Xen support is enabled
@@ -197,7 +195,6 @@ Do not modify the syntax of boot loader parameters without extreme
need or coordination with <Documentation/arch/x86/boot.rst>.
There are also arch-specific kernel-parameters not documented here.
-See for example <Documentation/arch/x86/x86_64/boot-options.rst>.
Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
a trailing = on the name of any parameter states that that parameter will
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7e1315ee0507..7f0f3d6aff37 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -21,6 +21,10 @@
strictly ACPI specification compliant.
rsdt -- prefer RSDT over (default) XSDT
copy_dsdt -- copy DSDT to memory
+ 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.
nospcr -- disable console in ACPI SPCR table as
default _serial_ console on ARM64
For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
@@ -405,6 +409,8 @@
not play well with APC CPU idle - disable it if you have
APC and your system crashes randomly.
+ apic [APIC,X86-64] Use IO-APIC. Default.
+
apic= [APIC,X86,EARLY] Advanced Programmable Interrupt Controller
Change the output verbosity while booting
Format: { quiet (default) | verbose | debug }
@@ -424,6 +430,10 @@
useful so that a dump capture kernel won't be
shot down by NMI
+ apicpmtimer Do APIC timer calibration using the pmtimer. Implies
+ apicmaintimer. Useful when your PIT timer is totally
+ broken.
+
autoconf= [IPV6]
See Documentation/networking/ipv6.rst.
@@ -1721,6 +1731,8 @@
off: Disable GDS mitigation.
+ gbpages [X86] Use GB pages for kernel direct mappings.
+
gcov_persist= [GCOV] When non-zero (default), profiling data for
kernel modules is saved and remains accessible via
debugfs, even when the module is unloaded/reloaded.
@@ -2003,12 +2015,21 @@
idle= [X86,EARLY]
Format: idle=poll, idle=halt, idle=nomwait
- Poll forces a polling idle loop that can slightly
- improve the performance of waking up a idle CPU, but
- will use a lot of power and make the system run hot.
- Not recommended.
+
+ 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.
+
idle=halt: Halt is forced to be used for CPU idle.
In such case C2/C3 won't be used again.
+
idle=nomwait: Disable mwait for CPU C-states
idxd.sva= [HW]
@@ -2306,19 +2327,50 @@
relaxed
iommu= [X86,EARLY]
- off
- force
- noforce
- biomerge
- panic
- nopanic
- merge
- nomerge
- soft
- pt [X86]
- nopt [X86]
- nobypass [PPC/POWERNV]
- Disable IOMMU bypass, using IOMMU for PCI devices.
+
+ off: Don't initialize and use any kind of IOMMU.
+
+ force: Force the use of the hardware IOMMU even when
+ it is not actually needed (e.g. because < 3 GB
+ memory).
+
+ noforce: Don't force hardware IOMMU usage when it is
+ not needed. (default).
+
+ biomerge
+ panic
+ nopanic
+ merge
+ nomerge
+
+ soft: Use software bounce buffering (SWIOTLB) (default
+ for Intel machines). This can be used to prevent the
+ usage of an available hardware IOMMU.
+
+ [X86]
+ pt
+ [X86]
+ nopt
+ [PPC/POWERNV]
+ nobypass: Disable IOMMU bypass, using IOMMU for PCI devices.
+
+ [X86]
+ AMD Gart HW IOMMU-specific options
+ <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.
+
+
iommu.forcedac= [ARM64,X86,EARLY] Control IOVA allocation for PCI devices.
Format: { "0" | "1" }
@@ -3254,9 +3306,68 @@
devices can be requested on-demand with the
/dev/loop-control interface.
- mce [X86-32] Machine Check Exception
+ mce= [X86-{32,64}]
+
+ Please see Documentation/arch/x86/x86_64/machinecheck.rst for sysfs runtime tunables.
+
+ off: disable machine check
+
+ 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.
+
+ 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.
+
+ 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.
+
+ no_lmce: do not opt-in to Local MCE delivery. Use
+ legacy method to broadcast MCEs.
+
+ 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.
+
+ nobootlog: disable boot machine check logging.
+
+ monarchtimeout (number): sets the time in us to wait
+ for other CPUs on machine checks. 0 to disable.
+
+ 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.
+
+ recovery: force-enable recoverable machine check code paths
+
+ Everything else is in sysfs now.
- mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
md= [HW] RAID subsystems devices and level
See Documentation/admin-guide/md.rst.
@@ -3882,6 +3993,8 @@
noapic [SMP,APIC,EARLY] Tells the kernel to not make use of any
IOAPICs that may be present in the system.
+ noapictimer [APIC,X86] Don't set up the APIC timer
+
noautogroup Disable scheduler automatic task group creation.
nocache [ARM,EARLY]
@@ -3929,6 +4042,8 @@
register save and restore. The kernel will only save
legacy floating-point registers on task switch.
+ nogbpages [X86] Do not use GB pages for kernel direct mappings.
+
no_hash_pointers
[KNL,EARLY]
Force pointers printed to the console or buffers to be
@@ -3955,6 +4070,8 @@
the impact of the sleep instructions. This is also
useful when using JTAG debugger.
+ nohpet [X86] Don't use the HPET timer.
+
nohugeiomap [KNL,X86,PPC,ARM64,EARLY] Disable kernel huge I/O mappings.
nohugevmalloc [KNL,X86,PPC,ARM64,EARLY] Disable kernel huge vmalloc mappings.
@@ -4106,8 +4223,10 @@
nosync [HW,M68K] Disables sync negotiation for all devices.
- no_timer_check [X86,APIC] Disables the code which tests for
- broken timer IRQ sources.
+ no_timer_check [X86,APIC] Disables the code which tests for broken
+ timer IRQ sources, i.e., the IO-APIC timer. This can
+ work around problems with incorrect timer
+ initialization on some boards.
no_uaccess_flush
[PPC,EARLY] Don't flush the L1-D cache after accessing user data.
@@ -4187,6 +4306,11 @@
If given as an integer followed by 'U', it will
divide each physical node into N emulated nodes.
+ numa=noacpi [X86] Don't parse the SRAT table for NUMA setup
+
+ numa=nohmat [X86] Don't parse the HMAT table for NUMA setup, or
+ soft-reserved memory partitioning.
+
numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
NUMA balancing.
Allowed values are enable and disable
@@ -5701,6 +5825,47 @@
reboot_cpu is s[mp]#### with #### being the processor
to be used for rebooting.
+ 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.
+
+ bios: Use the CPU reboot vector for warm reset
+
+ cold: Set the cold reboot flag
+
+ default: There are some built-in platform specific
+ "quirks" - you may see: "reboot: <name> series board
+ detected. Selecting <type> for reboots." In the case
+ where you think the quirk is in error (e.g. you have
+ newer BIOS, or newer board) using this option will
+ ignore the built-in quirk table, and use the generic
+ default reboot actions.
+
+ 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.
+
+ force: Don't stop other CPUs on reboot. This can make
+ reboot more reliable in some cases.
+
+ kbd: Use the keyboard controller. cold reset (default)
+
+ pci: Use a write to the PCI config space register
+ 0xcf9 to trigger reboot.
+
+ triple: Force a triple fault (init)
+
+ warm: Don't set the cold reboot flag
+
+ 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.
+
+
refscale.holdoff= [KNL]
Set test-start holdoff period. The purpose of
this parameter is to delay the start of the
@@ -6088,7 +6253,12 @@
serialnumber [BUGS=X86-32]
- sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst
+ sev=option[,option...] [X86-64]
+ debug: Enable debug messages.
+ nosnp: Do not enable SEV-SNP (applies to
+ host/hypervisor only). Setting 'nosnp' avoids the RMP
+ check overhead in memory accesses when users do not
+ want to run SEV-SNP guests.
shapers= [NET]
Maximal number of shapers.
diff --git a/Documentation/arch/x86/x86_64/boot-options.rst b/Documentation/arch/x86/x86_64/boot-options.rst
deleted file mode 100644
index d69e3cfbdba5..000000000000
--- a/Documentation/arch/x86/x86_64/boot-options.rst
+++ /dev/null
@@ -1,312 +0,0 @@
-.. 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/arch/x86/x86_64/machinecheck.rst 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=monarchtimeout (number)
- 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/arch/x86/i386/IO-APIC.rst
-
- 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] | p[ci] [, [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.
- pci
- Use a write to the PCI config space register 0xcf9 to trigger reboot.
-
- 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.
-
- reboot=default
- There are some built-in platform specific "quirks" - you may see:
- "reboot: <name> series board detected. Selecting <type> for reboots."
- In the case where you think the quirk is in error (e.g. you have
- newer BIOS, or newer board) using this option will ignore the built-in
- quirk table, and use the generic default reboot actions.
-
-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=nohmat
- Don't parse the HMAT table for NUMA setup, or soft-reserved memory
- partitioning.
-
-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. <kernel/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)"
-
-::
-
- iommu=[<size>][,noagp][,off][,force][,noforce]
- [,memaper[=<order>]][,merge][,fullflush][,nomerge]
- [,noaperture]
-
-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.
-
-iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU
-implementation:
-
- swiotlb=<slots>[,force,noforce]
- <slots>
- Prereserve that many 2K slots for the software IO bounce buffering.
- force
- Force all IO through the software TLB.
- noforce
- Do not initialize the software TLB.
-
-
-Miscellaneous
-=============
-
- nogbpages
- Do not use GB pages for kernel direct mappings.
- gbpages
- Use GB pages for kernel direct mappings.
-
-
-AMD SEV (Secure Encrypted Virtualization)
-=========================================
-Options relating to AMD SEV, specified via the following format:
-
-::
-
- sev=option1[,option2]
-
-The available options are:
-
- debug
- Enable debug messages.
-
- nosnp
- Do not enable SEV-SNP (applies to host/hypervisor only). Setting
- 'nosnp' avoids the RMP check overhead in memory accesses when
- users do not want to run SEV-SNP guests.
diff --git a/Documentation/arch/x86/x86_64/fake-numa-for-cpusets.rst b/Documentation/arch/x86/x86_64/fake-numa-for-cpusets.rst
index ba74617d4999..970ee94eb551 100644
--- a/Documentation/arch/x86/x86_64/fake-numa-for-cpusets.rst
+++ b/Documentation/arch/x86/x86_64/fake-numa-for-cpusets.rst
@@ -18,7 +18,7 @@ For more information on the features of cpusets, see
Documentation/admin-guide/cgroup-v1/cpusets.rst.
There are a number of different configurations you can use for your needs. For
more information on the numa=fake command line option and its various ways of
-configuring fake nodes, see Documentation/arch/x86/x86_64/boot-options.rst.
+configuring fake nodes, see Documentation/admin-guide/kernel-parameters.txt
For the purposes of this introduction, we'll assume a very primitive NUMA
emulation setup of "numa=fake=4*512,". This will split our system memory into
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 74777a97e394..1eb4d23cdaae 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -97,7 +97,7 @@ config IOMMU_DEBUG
code. When you use it make sure you have a big enough
IOMMU/AGP aperture. Most of the options enabled by this can
be set more finegrained using the iommu= command line
- options. See Documentation/arch/x86/x86_64/boot-options.rst for more
+ options. See Documentation/admin-guide/kernel-parameters.txt for more
details.
config IOMMU_LEAK
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index f323d83e40a7..6267363e0189 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -108,10 +108,6 @@ void __init pci_iommu_alloc(void)
swiotlb_init(x86_swiotlb_enable, x86_swiotlb_flags);
}
-/*
- * See <Documentation/arch/x86/x86_64/boot-options.rst> for the iommu kernel
- * parameter documentation.
- */
static __init int iommu_setup(char *p)
{
iommu_merge = 1;
--
2.43.0
