# Select CPU types depending on the architecture selected. This selects # which CPUs we support in the kernel image, and the compiler instruction # optimiser behaviour.
# ARM7TDMI
config CPU_ARM7TDMI bool
depends on !MMU
select CPU_32v4T
select CPU_ABRT_LV4T
select CPU_CACHE_V4
select CPU_PABRT_LEGACY
help
A 32-bit RISC microprocessor based on the ARM7 processor core
which has no memory control unit and cache.
Say Y if you want support for the ARM7TDMI processor.
Otherwise, say N.
# ARM720T
config CPU_ARM720T bool
select CPU_32v4T
select CPU_ABRT_LV4T
select CPU_CACHE_V4
select CPU_CACHE_VIVT
select CPU_COPY_V4WT if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WT if MMU
help
A 32-bit RISC processor with 8kByte Cache, Write Buffer and
MMU built around an ARM7TDMI core.
Say Y if you want support for the ARM720T processor.
Otherwise, say N.
# ARM740T
config CPU_ARM740T bool
depends on !MMU
select CPU_32v4T
select CPU_ABRT_LV4T
select CPU_CACHE_V4
select CPU_CP15_MPU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
help
A 32-bit RISC processor with 8KB cache or 4KB variants,
write buffer and MPU(Protection Unit) built around
an ARM7TDMI core.
Say Y if you want support for the ARM740T processor.
Otherwise, say N.
# ARM9TDMI
config CPU_ARM9TDMI bool
depends on !MMU
select CPU_32v4T
select CPU_ABRT_NOMMU
select CPU_CACHE_V4
select CPU_PABRT_LEGACY
help
A 32-bit RISC microprocessor based on the ARM9 processor core
which has no memory control unit and cache.
Say Y if you want support for the ARM9TDMI processor.
Otherwise, say N.
# ARM920T
config CPU_ARM920T bool
select CPU_32v4T
select CPU_ABRT_EV4T
select CPU_CACHE_V4WT
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
help
The ARM920T is licensed to be produced by numerous vendors, and is used in the Cirrus EP93xx and the Samsung S3C2410.
Say Y if you want support for the ARM920T processor.
Otherwise, say N.
# ARM922T
config CPU_ARM922T bool
select CPU_32v4T
select CPU_ABRT_EV4T
select CPU_CACHE_V4WT
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
help
The ARM922T is a version of the ARM920T, but with smaller
instruction and data caches. It is used in Altera's
Excalibur XA device family and the ARM Integrator.
Say Y if you want support for the ARM922T processor.
Otherwise, say N.
# ARM925T
config CPU_ARM925T bool
select CPU_32v4T
select CPU_ABRT_EV4T
select CPU_CACHE_V4WT
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
help
The ARM925T is a mix between the ARM920T and ARM926T, but with
different instruction and data caches. It is used in TI's OMAP
device family.
Say Y if you want support for the ARM925T processor.
Otherwise, say N.
# ARM926T
config CPU_ARM926T bool
select CPU_32v5
select CPU_ABRT_EV5TJ
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
help This is a variant of the ARM920. It has slightly different
instruction sequences for cache and TLB operations. Curiously,
there is no documentation on it at the ARM corporate website.
Say Y if you want support for the ARM926T processor.
Otherwise, say N.
# FA526
config CPU_FA526 bool
select CPU_32v4
select CPU_ABRT_EV4
select CPU_CACHE_FA
select CPU_CACHE_VIVT
select CPU_COPY_FA if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_TLB_FA if MMU
help
The FA526 is a version of the ARMv4 compatible processor with
Branch Target Buffer, Unified TLB and cache line size 16.
Say Y if you want support for the FA526 processor.
Otherwise, say N.
# ARM940T
config CPU_ARM940T bool
depends on !MMU
select CPU_32v4T
select CPU_ABRT_NOMMU
select CPU_CACHE_VIVT
select CPU_CP15_MPU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
help
ARM940T is a member of the ARM9TDMI family of general-
purpose microprocessors with MPU and separate 4KB
instruction and 4KB data cases, each with a 4-word line
length.
Say Y if you want support for the ARM940T processor.
Otherwise, say N.
# ARM946E-S
config CPU_ARM946E bool
depends on !MMU
select CPU_32v5
select CPU_ABRT_NOMMU
select CPU_CACHE_VIVT
select CPU_CP15_MPU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
help
ARM946E-S is a member of the ARM9E-S family of high-
performance, 32-bit system-on-chip processor solutions.
The TCM and ARMv5TE 32-bit instruction set is supported.
Say Y if you want support for the ARM946E-S processor.
Otherwise, say N.
# ARM1020 - needs validating
config CPU_ARM1020 bool
select CPU_32v5
select CPU_ABRT_EV4T
select CPU_CACHE_V4WT
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
help
The ARM1020 is the 32K cached version of the ARM10 processor,
with an addition of a floating-point unit.
Say Y if you want support for the ARM1020 processor.
Otherwise, say N.
# ARM1020E - needs validating
config CPU_ARM1020E bool
depends on n
select CPU_32v5
select CPU_ABRT_EV4T
select CPU_CACHE_V4WT
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
# ARM1022E
config CPU_ARM1022 bool
select CPU_32v5
select CPU_ABRT_EV4T
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU # can probably do better
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
help
The ARM1022E is an implementation of the ARMv5TE architecture
based upon the ARM10 integer core with a 16KiB L1 Harvard cache,
embedded trace macrocell, and a floating-point unit.
Say Y if you want support for the ARM1022E processor.
Otherwise, say N.
# ARM1026EJ-S
config CPU_ARM1026 bool
select CPU_32v5
select CPU_ABRT_EV5T # But need Jazelle, but EV5TJ ignores bit 10
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU # can probably do better
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_THUMB_CAPABLE
select CPU_TLB_V4WBI if MMU
help
The ARM1026EJ-S is an implementation of the ARMv5TEJ architecture
based upon the ARM10 integer core.
Say Y if you want support for the ARM1026EJ-S processor.
Otherwise, say N.
# SA110
config CPU_SA110 bool
select CPU_32v3 if ARCH_RPC
select CPU_32v4 if !ARCH_RPC
select CPU_ABRT_EV4
select CPU_CACHE_V4WB
select CPU_CACHE_VIVT
select CPU_COPY_V4WB if MMU
select CPU_CP15_MMU
select CPU_PABRT_LEGACY
select CPU_TLB_V4WB if MMU
help
The Intel StrongARM(R) SA-110 is a 32-bit microprocessor and
is available at five speeds ranging from 100 MHz to 233 MHz.
More information is available at
<http://developer.intel.com/design/strong/sa110.htm>.
Say Y if you want support for the SA-110 processor.
Otherwise, say N.
config CPU_FEROCEON_OLD_ID bool"Accept early Feroceon cores with an ARM926 ID"
depends on CPU_FEROCEON && !CPU_ARM926T default y
help This enables the usage of some old Feroceon cores for which the CPU ID is equal to the ARM926 ID.
Relevant for Feroceon-1850 and early Feroceon-2850.
config CPU_THUMBONLY bool
select CPU_THUMB_CAPABLE # There are no CPUs available with MMU that don't implement an ARM ISA:
depends on !MMU
help
Select thisif your CPU doesn't support the 32 bit ARM instructions.
config CPU_THUMB_CAPABLE bool
help
Select thisif your CPU can support Thumb mode.
# Figure out what processor architecture version we should be using. # This defines the compiler instruction set which depends on the machine type.
config CPU_32v3 bool
select CPU_USE_DOMAINS if MMU
select NEED_KUSER_HELPERS
select TLS_REG_EMUL if SMP || !MMU
select CPU_NO_EFFICIENT_FFS
config CPU_32v4 bool
select CPU_USE_DOMAINS if MMU
select NEED_KUSER_HELPERS
select TLS_REG_EMUL if SMP || !MMU
select CPU_NO_EFFICIENT_FFS
config CPU_32v4T bool
select CPU_USE_DOMAINS if MMU
select NEED_KUSER_HELPERS
select TLS_REG_EMUL if SMP || !MMU
select CPU_NO_EFFICIENT_FFS
config CPU_32v5 bool
select CPU_USE_DOMAINS if MMU
select NEED_KUSER_HELPERS
select TLS_REG_EMUL if SMP || !MMU
config CPU_32v6 bool
select TLS_REG_EMUL if !CPU_32v6K && !MMU
config CPU_32v6K bool
config CPU_32v7 bool
config CPU_32v7M bool
# The abort model
config CPU_ABRT_NOMMU bool
config CPU_ABRT_EV4 bool
config CPU_ABRT_EV4T bool
config CPU_ABRT_LV4T bool
config CPU_ABRT_EV5T bool
config CPU_ABRT_EV5TJ bool
config CPU_ABRT_EV6 bool
config CPU_ABRT_EV7 bool
config CPU_PABRT_LEGACY bool
config CPU_PABRT_V6 bool
config CPU_PABRT_V7 bool
# The cache model
config CPU_CACHE_V4 bool
config CPU_CACHE_V4WT bool
config CPU_CACHE_V4WB bool
config CPU_CACHE_V6 bool
config CPU_CACHE_V7 bool
config CPU_CACHE_NOP bool
config CPU_CACHE_VIVT bool
config CPU_CACHE_VIPT bool
config CPU_CACHE_FA bool
config CPU_CACHE_V7M bool
if MMU # The copy-page model
config CPU_COPY_V4WT bool
config CPU_COPY_V4WB bool
config CPU_COPY_FEROCEON bool
config CPU_COPY_FA bool
config CPU_COPY_V6 bool
# This selects the TLB model
config CPU_TLB_V4WT bool
help
ARM Architecture Version 4 TLB with writethrough cache.
config CPU_TLB_V4WB bool
help
ARM Architecture Version 4 TLB with writeback cache.
config CPU_TLB_V4WBI bool
help
ARM Architecture Version 4 TLB with writeback cache and invalidate
instruction cache entry.
config CPU_TLB_FEROCEON bool
help
Feroceon TLB (v4wbi with non-outer-cachable page table walks).
config CPU_TLB_FA bool
help
Faraday ARM FA526 architecture, unified TLB with writeback cache and invalidate instruction cache entry. Branch target buffer is
also supported.
config CPU_TLB_V6 bool
config CPU_TLB_V7 bool
endif
config CPU_HAS_ASID bool
help This indicates whether the CPU has the ASID register; used to
tag TLB and possibly cache entries.
config CPU_CP15 bool
help
Processor has the CP15 register.
config CPU_CP15_MMU bool
select CPU_CP15
help
Processor has the CP15 register, which has MMU related registers.
config CPU_CP15_MPU bool
select CPU_CP15
help
Processor has the CP15 register, which has MPU related registers.
config CPU_USE_DOMAINS bool
help This option enables or disables the use of domain switching using the DACR (domain access control register) to protect memory
domains from each other. In Linux we use three domains: kernel, user and IO. The domains are used to protect userspace from kernelspace and to handle IO-space as a special type of memory by assigning
manager or client roles to running code (such as a process).
config CPU_V7M_NUM_IRQ int"Number of external interrupts connected to the NVIC"
depends on CPU_V7M default 90 if ARCH_STM32 default 112 if SOC_VF610 default 240
help This option indicates the number of interrupts connected to the NVIC.
The value can be larger than the real number of interrupts supported
by the system, but must not be lower.
The default value is 240, corresponding to the maximum number of
interrupts supported by the NVIC on Cortex-M family.
If unsure, keep default value.
java.lang.NullPointerException # CPU supports 36-bit I/O
java.lang.NullPointerException
config IO_36 bool
comment "Processor Features"
config ARM_LPAE bool"Support for the Large Physical Address Extension"
depends on MMU && CPU_32v7 && !CPU_32v6 && !CPU_32v5 && \
!CPU_32v4 && !CPU_32v3
select PHYS_ADDR_T_64BIT
select SWIOTLB
help
Say Y if you have an ARMv7 processor supporting the LPAE page
table format and you would like to access memory beyond the
4GB limit. The resulting kernel image will not run on
processors without the LPA extension.
If unsure, say N.
config ARM_PV_FIXUP
def_bool y
depends on ARM_LPAE && ARM_PATCH_PHYS_VIRT && ARCH_KEYSTONE
config ARM_THUMB bool"Support Thumb user binaries"if !CPU_THUMBONLY && EXPERT
depends on CPU_THUMB_CAPABLE && !CPU_32v4 default y
help
Say Y if you want to include kernel support for running user space
Thumb binaries.
The Thumb instruction set is a compressed form of the standard ARM
instruction set resulting in smaller binaries at the expense of
slightly less efficient code.
Ifthis option is disabled, and you run userspace that switches to
Thumb mode, signal handling will not work correctly, resulting in
segmentation faults or illegal instruction aborts.
If you don't know what this all is, saying Y is a safe choice.
config ARM_THUMBEE bool"Enable ThumbEE CPU extension"
depends on CPU_V7
help
Say Y here if you have a CPU with the ThumbEE extension and code to
make use of it. Say N for code that can run on CPUs without ThumbEE.
config ARM_VIRT_EXT bool default y if CPU_V7
help
Enable the kernel to make use of the ARM Virtualization
Extensions to install hypervisors without run-time firmware
assistance.
A compliant bootloader is required in order to make maximum
use of this feature. Refer to Documentation/arch/arm/booting.rst for
details.
config SWP_EMULATE bool"Emulate SWP/SWPB instructions"if !SMP
depends on CPU_V7 default y if SMP
select HAVE_PROC_CPU if PROC_FS
help
ARMv6 architecture deprecates use of the SWP/SWPB instructions.
ARMv7 multiprocessing extensions introduce the ability to disable
these instructions, triggering an undefined instruction exception
when executed. Say Y here to enable software emulation of these
instructions for userspace (not kernel) using LDREX/STREX.
Also creates /proc/cpu/swp_emulation for statistics.
In some older versions of glibc [<=2.8] SWP is used during futex
trylock() operations with the assumption that the code will not
be preempted. This invalid assumption may be more likely to fail
with SWP emulation enabled, leading to deadlock of the user
application.
NOTE: when accessing uncached shared regions, LDREX/STREX rely
on an external transaction monitoring block called a global
monitor to maintain update atomicity. If your system does not
implement a global monitor, this option can cause programs that
perform SWP operations to uncached memory to deadlock.
config CPU_LITTLE_ENDIAN bool"Built little-endian kernel"
help
Say Y if you plan on running a kernel in little-endian mode. This is the defaultand is used in practically all modern user
space builds.
config CPU_BIG_ENDIAN bool"Build big-endian kernel"
depends on !LD_IS_LLD
help
Say Y if you plan on running a kernel in big-endian mode. This works on many machines using ARMv6 or newer processors
but requires big-endian user space.
The only ARMv5 platform with big-endian support is
Intel IXP4xx.
endchoice
config CPU_ENDIAN_BE8 bool
depends on CPU_BIG_ENDIAN default CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M
help
Support for the BE-8 (big-endian) mode on ARMv6 and ARMv7 processors.
config CPU_ENDIAN_BE32 bool
depends on CPU_BIG_ENDIAN default !CPU_ENDIAN_BE8
help
Support for the BE-32 (big-endian) mode on pre-ARMv6 processors.
config CPU_HIGH_VECTOR
depends on !MMU && CPU_CP15 && !CPU_ARM740T bool"Select the High exception vector"
help
Say Y here to select high exception vector(0xFFFF0000~).
The exception vector can vary depending on the platform
design in nommu mode. If your platform needs to select
high exception vector, say Y.
Otherwise orif you are unsure, say N, and the low exception
vector (0x00000000~) will be used.
config CPU_ICACHE_DISABLE bool"Disable I-Cache (I-bit)"
depends on (CPU_CP15 && !(CPU_ARM720T || CPU_ARM740T || CPU_XSCALE || CPU_XSC3)) || CPU_V7M
help
Say Y here to disable the processor instruction cache. Unless
you have a reason not to or are unsure, say N.
config CPU_ICACHE_MISMATCH_WORKAROUND bool"Workaround for I-Cache line size mismatch between CPU cores"
depends on SMP && CPU_V7
help
Some big.LITTLE systems have I-Cache line size mismatch between
LITTLE and big cores. Say Y here to enable a workaround for
proper I-Cache support on such systems. If unsure, say N.
config CPU_DCACHE_DISABLE bool"Disable D-Cache (C-bit)"
depends on (CPU_CP15 && !SMP) || CPU_V7M
help
Say Y here to disable the processor data cache. Unless
you have a reason not to or are unsure, say N.
config CPU_DCACHE_SIZE
hex
depends on CPU_ARM740T || CPU_ARM946E default 0x00001000 if CPU_ARM740T default 0x00002000 # default size for ARM946E-S
help
Some cores are synthesizable to have various sized cache. For
ARM946E-S case, it can vary from 0KB to 1MB.
To support such cache operations, it is efficient to know the size
before compile time. If your SoC is configured to have a different size, define the value
here with proper conditions.
config CPU_DCACHE_WRITETHROUGH bool"Force write through D-cache"
depends on (CPU_ARM740T || CPU_ARM920T || CPU_ARM922T || CPU_ARM925T || CPU_ARM926T || CPU_ARM940T || CPU_ARM946E || CPU_ARM1020 || CPU_FA526) && !CPU_DCACHE_DISABLE default y if CPU_ARM925T
help
Say Y here to use the data cache in writethrough mode. Unless you
specifically require thisor are unsure, say N.
config CPU_CACHE_ROUND_ROBIN bool"Round robin I and D cache replacement algorithm"
depends on (CPU_ARM926T || CPU_ARM946E || CPU_ARM1020) && (!CPU_ICACHE_DISABLE || !CPU_DCACHE_DISABLE)
help
Say Y here to use the predictable round-robin cache replacement
policy. Unless you specifically require thisor are unsure, say N.
config CPU_BPREDICT_DISABLE bool"Disable branch prediction"
depends on CPU_ARM1020 || CPU_V6 || CPU_V6K || CPU_MOHAWK || CPU_XSC3 || CPU_V7 || CPU_FA526 || CPU_V7M
help
Say Y here to disable branch prediction. If unsure, say N.
config HARDEN_BRANCH_PREDICTOR bool"Harden the branch predictor against aliasing attacks"if EXPERT
depends on CPU_SPECTRE default y
help
Speculation attacks against some high-performance processors rely
on being able to manipulate the branch predictor for a victim
context by executing aliasing branches in the attacker context.
Such attacks can be partially mitigated against by clearing
internal branch predictor state and limiting the prediction
logic in some situations.
This config option will take CPU-specific actions to harden
the branch predictor against aliasing attacks and may rely on
specific instruction sequences or control bits being set by
the system firmware.
If unsure, say Y.
config HARDEN_BRANCH_HISTORY bool"Harden Spectre style attacks against branch history"if EXPERT
depends on CPU_SPECTRE default y
help
Speculation attacks against some high-performance processors can
make use of branch history to influence future speculation. When
taking an exception, a sequence of branches overwrites the branch
history, or branch history is invalidated.
config TLS_REG_EMUL bool
select NEED_KUSER_HELPERS
help
An SMP system using a pre-ARMv6 processor (there are apparently
a few prototypes like that in existence) and therefore access to
that required register must be emulated.
config NEED_KUSER_HELPERS bool
config KUSER_HELPERS bool"Enable kuser helpers in vector page"if !NEED_KUSER_HELPERS
depends on MMU default y
help
Warning: disabling this option may break user programs.
Provide kuser helpers in the vector page. The kernel provides
helper code to userspace in read only form at a fixed location
in the high vector page to allow userspace to be independent of
the CPU type fitted to the system. This permits binaries to be
run on ARMv4 through to ARMv7 without modification.
See Documentation/arch/arm/kernel_user_helpers.rst for details.
However, the fixed address nature of these helpers can be used
by ROP (return orientated programming) authors when creating
exploits.
If all of the binaries and libraries which run on your platform
are built specifically for your platform, and make no use of
these helpers, then you can turn this option off to hinder
such exploits. However, in that case, if a binary or library
relying on those helpers is run, it will receive a SIGILL signal,
which will terminate the program.
Say N here only if you are absolutely certain that you donot
need these helpers; otherwise, the safe option is to say Y.
config VDSO bool"Enable VDSO for acceleration of some system calls"
depends on AEABI && MMU && CPU_V7 default y if ARM_ARCH_TIMER
select HAVE_GENERIC_VDSO
select GENERIC_TIME_VSYSCALL
select GENERIC_VDSO_32
select GENERIC_GETTIMEOFDAY
select GENERIC_VDSO_DATA_STORE
help
Place in the process address space an ELF shared object
providing fast implementations of gettimeofday and
clock_gettime. Systems that implement the ARM architected
timer will receive maximum benefit.
You must have glibc 2.22 or later for programs to seamlessly
take advantage of this.
config OUTER_CACHE bool
config OUTER_CACHE_SYNC bool
select ARM_HEAVY_MB
help
The outer cache has a outer_cache_fns.sync function pointer
that can be used to drain the write buffer of the outer cache.
config CACHE_B15_RAC bool"Enable the Broadcom Brahma-B15 read-ahead cache controller"
depends on ARCH_BRCMSTB default y
help This option enables the Broadcom Brahma-B15 read-ahead cache
controller. If disabled, the read-ahead cache remains off.
config CACHE_FEROCEON_L2 bool"Enable the Feroceon L2 cache controller"
depends on ARCH_MV78XX0 || ARCH_MVEBU default y
select OUTER_CACHE
help This option enables the Feroceon L2 cache controller.
config CACHE_FEROCEON_L2_WRITETHROUGH bool"Force Feroceon L2 cache write through"
depends on CACHE_FEROCEON_L2
help
Say Y here to use the Feroceon L2 cache in writethrough mode.
Unless you specifically require this, say N for writeback mode.
config MIGHT_HAVE_CACHE_L2X0 bool
help This option should be selected by machines which have a L2x0 or PL310 cache controller, but where its use is optional.
The only effect of this option is to make CACHE_L2X0 and
related options available to the user for configuration.
Boards or SoCs which always require the cache controller
support to be present should select CACHE_L2X0 directly
instead of this option, thus preventing the user from
inadvertently configuring a broken kernel.
config CACHE_L2X0 bool"Enable the L2x0 outer cache controller"if MIGHT_HAVE_CACHE_L2X0 default MIGHT_HAVE_CACHE_L2X0
select OUTER_CACHE
select OUTER_CACHE_SYNC
help This option enables the L2x0 PrimeCell.
config CACHE_L2X0_PMU bool"L2x0 performance monitor support"if CACHE_L2X0
depends on PERF_EVENTS
help This option enables support for the performance monitoring features
of the L220 and PL310 outer cache controllers.
if CACHE_L2X0
config PL310_ERRATA_588369 bool"PL310 errata: Clean & Invalidate maintenance operations do not invalidate clean lines"
help
The PL310 L2 cache controller implements three types of Clean &
Invalidate maintenance operations: by Physical Address
(offset 0x7F0), by Index/Way (0x7F8) and by Way (0x7FC).
They are architecturally defined to behave as the execution of a
clean operation followed immediately by an invalidate operation,
both performing to the same memory location. This functionality
is not correctly implemented in PL310 prior to r2p0 (fixed in r2p0)
as clean lines are not invalidated as a result of these operations.
config PL310_ERRATA_727915 bool"PL310 errata: Background Clean & Invalidate by Way operation can cause data corruption"
help
PL310 implements the Clean & Invalidate by Way L2 cache maintenance
operation (offset 0x7FC). This operation runs in background so that
PL310 can handle normal accesses while it is in progress. Under very
rare circumstances, due to this erratum, write data can be lost when
PL310 treats a cacheable write transaction during a Clean &
Invalidate by Way operation. Revisions prior to r3p1 are affected by this errata (fixed in r3p1).
config PL310_ERRATA_753970 bool"PL310 errata: cache sync operation may be faulty"
help This option enables the workaround for the 753970 PL310 (r3p0) erratum.
Under some condition the effect of cache sync operation on
the store buffer still remains when the operation completes. This means that the store buffer is always asked to drain and this prevents it from merging any further writes. The workaround
is to replace the normal offset of cache sync operation (0x730)
by another offset targeting an unmapped PL310 register 0x740. This has the same effect as the cache sync operation: store buffer
drain and waiting for all buffers empty.
config PL310_ERRATA_769419 bool"PL310 errata: no automatic Store Buffer drain"
help
On revisions of the PL310 prior to r3p2, the Store Buffer does not automatically drain. This can cause normal, non-cacheable
writes to be retained when the memory system is idle, leading
to suboptimal I/O performance for drivers using coherent DMA. This option adds a write barrier to the cpu_idle loop so that,
on systems with an outer cache, the store buffer is drained
explicitly.
endif
config CACHE_TAUROS2 bool"Enable the Tauros2 L2 cache controller"
depends on (CPU_MOHAWK || CPU_PJ4) default y
select OUTER_CACHE
help This option enables the Tauros2 L2 cache controller (as
found on PJ1/PJ4).
config CACHE_UNIPHIER bool"Enable the UniPhier outer cache controller"
depends on ARCH_UNIPHIER
select ARM_L1_CACHE_SHIFT_7
select OUTER_CACHE
select OUTER_CACHE_SYNC
help This option enables the UniPhier outer cache (system cache)
controller.
config CACHE_XSC3L2 bool"Enable the L2 cache on XScale3"
depends on CPU_XSC3 default y
select OUTER_CACHE
help This option enables the L2 cache on XScale3.
config ARM_L1_CACHE_SHIFT_6 bool default y if CPU_V7
help
Setting ARM L1 cache line size to 64 Bytes.
config ARM_L1_CACHE_SHIFT_7 bool
help
Setting ARM L1 cache line size to 128 Bytes.
config ARM_L1_CACHE_SHIFT int default 7 if ARM_L1_CACHE_SHIFT_7 default 6 if ARM_L1_CACHE_SHIFT_6 default 5
config ARM_DMA_MEM_BUFFERABLE bool"Use non-cacheable memory for DMA"if (CPU_V6 || CPU_V6K || CPU_V7M) && !CPU_V7 default y if CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M
help
Historically, the kernel has used strongly ordered mappings to
provide DMA coherent memory. With the advent of ARMv7, mapping
memory with differing types results in unpredictable behaviour,
so on these CPUs, this option is forced on.
Multiple mappings with differing attributes is also unpredictable
on ARMv6 CPUs, but since they donot have aggressive speculative
prefetch, no harm appears to occur.
However, drivers may be missing the necessary barriers for ARMv6, and therefore turning this on may result in unpredictable driver
behaviour. Therefore, we offer this as an option.
On some of the beefier ARMv7-M machines (with DMA and write
buffers) you likely want this enabled, while those that
didn't need it until now also won't need it in the future.
You are recommended say 'Y' here and debug any affected drivers.
config ARM_HEAVY_MB bool
config DEBUG_ALIGN_RODATA bool"Make rodata strictly non-executable"
depends on STRICT_KERNEL_RWX default y
help Ifthis is set, rodata will be made explicitly non-executable. This
provides protection on the rare chance that attackers might find and
use ROP gadgets that exist in the rodata section. This adds an
additional section-aligned split of rodata from kernel text so it
can be made explicitly non-executable. This padding may waste memory
space to gain the additional protection.
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