linux/arch/loongarch/Kconfig
Tiezhu Yang 5685d7fcb5 LoongArch: Give a chance to build with !CONFIG_SMP
In the current code, SMP is selected in Kconfig for LoongArch, the users
can not unset it, this is reasonable for a multi-processor machine. But
as the help info of config SMP said, if you have a system with only one
CPU, say N. On a uni-processor machine, the kernel will run faster if you
say N here.

Loongson-2K0500 is a single-core CPU for applications like industrial
control, printing terminals, and BMC (Baseboard Management Controller),
there are many development boards, products and solutions on the market,
so it is better and necessary to give a chance to build with !CONFIG_SMP
for a uni-processor machine.

First of all, do not select SMP for config LOONGARCH in Kconfig to make
it possible to unset CONFIG_SMP. Then, do some changes to fix warnings
and errors if CONFIG_SMP is not set.

(1) Define get_ipi_irq() only if CONFIG_SMP is set to fix the warning:
arch/loongarch/kernel/irq.c:90:19: warning: 'get_ipi_irq' defined but not used [-Wunused-function]

(2) Add "#ifdef CONFIG_SMP" in asm/smp.h to fix the warning:
./arch/loongarch/include/asm/smp.h:49:9: warning: "raw_smp_processor_id" redefined
   49 | #define raw_smp_processor_id raw_smp_processor_id
      |         ^~~~~~~~~~~~~~~~~~~~
./include/linux/smp.h:198:9: note: this is the location of the previous definition
  198 | #define raw_smp_processor_id()                  0

(3) Define machine_shutdown() as empty under !CONFIG_SMP to fix the error:
arch/loongarch/kernel/machine_kexec.c: In function 'machine_shutdown':
arch/loongarch/kernel/machine_kexec.c:233:25: error: implicit declaration of function 'cpu_device_up'; did you mean 'put_device'? [-Wimplicit-function-declaration]

(4) Make config SCHED_SMT depends on SMP to fix many errors such as:
kernel/sched/core.c: In function 'sched_core_find':
kernel/sched/core.c:310:43: error: 'struct rq' has no member named 'cpu'

(5) Define cpu_logical_map(cpu) as 0 under !CONFIG_SMP in asm/smp.h,
then include asm/smp.h in asm/acpi.h (because acpi.h is included in
linux/irq.h indirectly) to fix many build errors under drivers/irqchip
such as:
drivers/irqchip/irq-loongson-eiointc.c: In function 'cpu_to_eio_node':
drivers/irqchip/irq-loongson-eiointc.c:59:16: error: implicit declaration of function 'cpu_logical_map' [-Wimplicit-function-declaration]

(6) Do not write per_cpu_offset(0) to PERCPU_BASE_KS when resume because
the per_cpu_offset(x) macro is defined as (__per_cpu_offset[x]) only
under CONFIG_SMP in include/asm-generic/percpu.h. Just save the value of
PERCPU_BASE_KS when suspend and restore it when resume to fix the error:
arch/loongarch/power/suspend.c: In function 'loongarch_common_resume':
arch/loongarch/power/suspend.c:47:21: error: implicit declaration of function 'per_cpu_offset' [-Wimplicit-function-declaration]

(7) Fix huge page handling under !CONFIG_SMP in tlbex.S.

When running the UnixBench tests with "-c 1" single-streamed pass, the
improvement of performance is about 9 percent with this patch.

By the way, it is helpful to debug and analysis the kernel issues of
multi-processor system under !CONFIG_SMP.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-05-14 12:24:18 +08:00

693 lines
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# SPDX-License-Identifier: GPL-2.0
config LOONGARCH
bool
default y
select ACPI
select ACPI_GENERIC_GSI if ACPI
select ACPI_MCFG if ACPI
select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
select ACPI_PPTT if ACPI
select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
select ARCH_BINFMT_ELF_STATE
select ARCH_DISABLE_KASAN_INLINE
select ARCH_ENABLE_MEMORY_HOTPLUG
select ARCH_ENABLE_MEMORY_HOTREMOVE
select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_FAST_MULTIPLIER
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_KCOV
select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_INLINE_READ_LOCK if !PREEMPTION
select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
select ARCH_INLINE_READ_LOCK_IRQ if !PREEMPTION
select ARCH_INLINE_READ_LOCK_IRQSAVE if !PREEMPTION
select ARCH_INLINE_READ_UNLOCK if !PREEMPTION
select ARCH_INLINE_READ_UNLOCK_BH if !PREEMPTION
select ARCH_INLINE_READ_UNLOCK_IRQ if !PREEMPTION
select ARCH_INLINE_READ_UNLOCK_IRQRESTORE if !PREEMPTION
select ARCH_INLINE_WRITE_LOCK if !PREEMPTION
select ARCH_INLINE_WRITE_LOCK_BH if !PREEMPTION
select ARCH_INLINE_WRITE_LOCK_IRQ if !PREEMPTION
select ARCH_INLINE_WRITE_LOCK_IRQSAVE if !PREEMPTION
select ARCH_INLINE_WRITE_UNLOCK if !PREEMPTION
select ARCH_INLINE_WRITE_UNLOCK_BH if !PREEMPTION
select ARCH_INLINE_WRITE_UNLOCK_IRQ if !PREEMPTION
select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE if !PREEMPTION
select ARCH_INLINE_SPIN_TRYLOCK if !PREEMPTION
select ARCH_INLINE_SPIN_TRYLOCK_BH if !PREEMPTION
select ARCH_INLINE_SPIN_LOCK if !PREEMPTION
select ARCH_INLINE_SPIN_LOCK_BH if !PREEMPTION
select ARCH_INLINE_SPIN_LOCK_IRQ if !PREEMPTION
select ARCH_INLINE_SPIN_LOCK_IRQSAVE if !PREEMPTION
select ARCH_INLINE_SPIN_UNLOCK if !PREEMPTION
select ARCH_INLINE_SPIN_UNLOCK_BH if !PREEMPTION
select ARCH_INLINE_SPIN_UNLOCK_IRQ if !PREEMPTION
select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE if !PREEMPTION
select ARCH_KEEP_MEMBLOCK
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select ARCH_SPARSEMEM_ENABLE
select ARCH_STACKWALK
select ARCH_SUPPORTS_ACPI
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_HUGETLBFS
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
select ARCH_SUPPORTS_LTO_CLANG
select ARCH_SUPPORTS_LTO_CLANG_THIN
select ARCH_SUPPORTS_NUMA_BALANCING
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_CMPXCHG_LOCKREF
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_USE_QUEUED_SPINLOCKS
select ARCH_WANT_DEFAULT_BPF_JIT
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
select ARCH_WANT_LD_ORPHAN_WARN
select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
select ARCH_WANTS_NO_INSTR
select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
select BUILDTIME_TABLE_SORT
select COMMON_CLK
select CPU_PM
select EFI
select GENERIC_CLOCKEVENTS
select GENERIC_CMOS_UPDATE
select GENERIC_CPU_AUTOPROBE
select GENERIC_CPU_DEVICES
select GENERIC_ENTRY
select GENERIC_GETTIMEOFDAY
select GENERIC_IOREMAP if !ARCH_IOREMAP
select GENERIC_IRQ_MULTI_HANDLER
select GENERIC_IRQ_PROBE
select GENERIC_IRQ_SHOW
select GENERIC_LIB_ASHLDI3
select GENERIC_LIB_ASHRDI3
select GENERIC_LIB_CMPDI2
select GENERIC_LIB_LSHRDI3
select GENERIC_LIB_UCMPDI2
select GENERIC_LIB_DEVMEM_IS_ALLOWED
select GENERIC_PCI_IOMAP
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_TIME_VSYSCALL
select GENERIC_VDSO_TIME_NS
select GPIOLIB
select HAS_IOPORT
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_JUMP_LABEL_RELATIVE
select HAVE_ARCH_KASAN
select HAVE_ARCH_KFENCE
select HAVE_ARCH_KGDB if PERF_EVENTS
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_SECCOMP
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD
select HAVE_ASM_MODVERSIONS
select HAVE_CONTEXT_TRACKING_USER
select HAVE_C_RECORDMCOUNT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DEBUG_STACKOVERFLOW
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_ARGS
select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
select HAVE_DYNAMIC_FTRACE_WITH_REGS
select HAVE_EBPF_JIT
select HAVE_EFFICIENT_UNALIGNED_ACCESS if !ARCH_STRICT_ALIGN
select HAVE_EXIT_THREAD
select HAVE_FAST_GUP
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS
select HAVE_GENERIC_VDSO
select HAVE_HW_BREAKPOINT if PERF_EVENTS
select HAVE_IOREMAP_PROT
select HAVE_IRQ_EXIT_ON_IRQ_STACK
select HAVE_IRQ_TIME_ACCOUNTING
select HAVE_KPROBES
select HAVE_KPROBES_ON_FTRACE
select HAVE_KRETPROBES
select HAVE_LIVEPATCH
select HAVE_MOD_ARCH_SPECIFIC
select HAVE_NMI
select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS
select HAVE_PCI
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_PREEMPT_DYNAMIC_KEY
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC
select HAVE_RETHOOK
select HAVE_RSEQ
select HAVE_RUST
select HAVE_SAMPLE_FTRACE_DIRECT
select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
select HAVE_SETUP_PER_CPU_AREA if NUMA
select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_TIF_NOHZ
select HAVE_VIRT_CPU_ACCOUNTING_GEN if !SMP
select IRQ_FORCED_THREADING
select IRQ_LOONGARCH_CPU
select LOCK_MM_AND_FIND_VMA
select MMU_GATHER_MERGE_VMAS if MMU
select MODULES_USE_ELF_RELA if MODULES
select NEED_PER_CPU_EMBED_FIRST_CHUNK
select NEED_PER_CPU_PAGE_FIRST_CHUNK
select OF
select OF_EARLY_FLATTREE
select PCI
select PCI_DOMAINS_GENERIC
select PCI_ECAM if ACPI
select PCI_LOONGSON
select PCI_MSI_ARCH_FALLBACKS
select PCI_QUIRKS
select PERF_USE_VMALLOC
select RTC_LIB
select SPARSE_IRQ
select SYSCTL_ARCH_UNALIGN_ALLOW
select SYSCTL_ARCH_UNALIGN_NO_WARN
select SYSCTL_EXCEPTION_TRACE
select SWIOTLB
select TRACE_IRQFLAGS_SUPPORT
select USE_PERCPU_NUMA_NODE_ID
select USER_STACKTRACE_SUPPORT
select ZONE_DMA32
config 32BIT
bool
config 64BIT
def_bool y
config GENERIC_BUG
def_bool y
depends on BUG
config GENERIC_BUG_RELATIVE_POINTERS
def_bool y
depends on GENERIC_BUG
config GENERIC_CALIBRATE_DELAY
def_bool y
config GENERIC_CSUM
def_bool y
config GENERIC_HWEIGHT
def_bool y
config L1_CACHE_SHIFT
int
default "6"
config LOCKDEP_SUPPORT
bool
default y
config STACKTRACE_SUPPORT
bool
default y
# MACH_LOONGSON32 and MACH_LOONGSON64 are deliberately carried over from the
# MIPS Loongson code, to preserve Loongson-specific code paths in drivers that
# are shared between architectures, and specifically expecting the symbols.
config MACH_LOONGSON32
def_bool 32BIT
config MACH_LOONGSON64
def_bool 64BIT
config FIX_EARLYCON_MEM
def_bool y
config PGTABLE_2LEVEL
bool
config PGTABLE_3LEVEL
bool
config PGTABLE_4LEVEL
bool
config PGTABLE_LEVELS
int
default 2 if PGTABLE_2LEVEL
default 3 if PGTABLE_3LEVEL
default 4 if PGTABLE_4LEVEL
config SCHED_OMIT_FRAME_POINTER
bool
default y
config AS_HAS_EXPLICIT_RELOCS
def_bool $(as-instr,x:pcalau12i \$t0$(comma)%pc_hi20(x))
config AS_HAS_FCSR_CLASS
def_bool $(as-instr,movfcsr2gr \$t0$(comma)\$fcsr0)
config AS_HAS_LSX_EXTENSION
def_bool $(as-instr,vld \$vr0$(comma)\$a0$(comma)0)
config AS_HAS_LASX_EXTENSION
def_bool $(as-instr,xvld \$xr0$(comma)\$a0$(comma)0)
config AS_HAS_LBT_EXTENSION
def_bool $(as-instr,movscr2gr \$a0$(comma)\$scr0)
config AS_HAS_LVZ_EXTENSION
def_bool $(as-instr,hvcl 0)
menu "Kernel type and options"
source "kernel/Kconfig.hz"
choice
prompt "Page Table Layout"
default 16KB_2LEVEL if 32BIT
default 16KB_3LEVEL if 64BIT
help
Allows choosing the page table layout, which is a combination
of page size and page table levels. The size of virtual memory
address space are determined by the page table layout.
config 4KB_3LEVEL
bool "4KB with 3 levels"
select HAVE_PAGE_SIZE_4KB
select PGTABLE_3LEVEL
help
This option selects 4KB page size with 3 level page tables, which
support a maximum of 39 bits of application virtual memory.
config 4KB_4LEVEL
bool "4KB with 4 levels"
select HAVE_PAGE_SIZE_4KB
select PGTABLE_4LEVEL
help
This option selects 4KB page size with 4 level page tables, which
support a maximum of 48 bits of application virtual memory.
config 16KB_2LEVEL
bool "16KB with 2 levels"
select HAVE_PAGE_SIZE_16KB
select PGTABLE_2LEVEL
help
This option selects 16KB page size with 2 level page tables, which
support a maximum of 36 bits of application virtual memory.
config 16KB_3LEVEL
bool "16KB with 3 levels"
select HAVE_PAGE_SIZE_16KB
select PGTABLE_3LEVEL
help
This option selects 16KB page size with 3 level page tables, which
support a maximum of 47 bits of application virtual memory.
config 64KB_2LEVEL
bool "64KB with 2 levels"
select HAVE_PAGE_SIZE_64KB
select PGTABLE_2LEVEL
help
This option selects 64KB page size with 2 level page tables, which
support a maximum of 42 bits of application virtual memory.
config 64KB_3LEVEL
bool "64KB with 3 levels"
select HAVE_PAGE_SIZE_64KB
select PGTABLE_3LEVEL
help
This option selects 64KB page size with 3 level page tables, which
support a maximum of 55 bits of application virtual memory.
endchoice
config CMDLINE
string "Built-in kernel command line"
help
For most platforms, the arguments for the kernel's command line
are provided at run-time, during boot. However, there are cases
where either no arguments are being provided or the provided
arguments are insufficient or even invalid.
When that occurs, it is possible to define a built-in command
line here and choose how the kernel should use it later on.
choice
prompt "Kernel command line type"
default CMDLINE_BOOTLOADER
help
Choose how the kernel will handle the provided built-in command
line.
config CMDLINE_BOOTLOADER
bool "Use bootloader kernel arguments if available"
help
Prefer the command-line passed by the boot loader if available.
Use the built-in command line as fallback in case we get nothing
during boot. This is the default behaviour.
config CMDLINE_EXTEND
bool "Use built-in to extend bootloader kernel arguments"
help
The command-line arguments provided during boot will be
appended to the built-in command line. This is useful in
cases where the provided arguments are insufficient and
you don't want to or cannot modify them.
config CMDLINE_FORCE
bool "Always use the built-in kernel command string"
help
Always use the built-in command line, even if we get one during
boot. This is useful in case you need to override the provided
command line on systems where you don't have or want control
over it.
endchoice
config BUILTIN_DTB
bool "Enable built-in dtb in kernel"
depends on OF
help
Some existing systems do not provide a canonical device tree to
the kernel at boot time. Let's provide a device tree table in the
kernel, keyed by the dts filename, containing the relevant DTBs.
Built-in DTBs are generic enough and can be used as references.
config BUILTIN_DTB_NAME
string "Source file for built-in dtb"
depends on BUILTIN_DTB
help
Base name (without suffix, relative to arch/loongarch/boot/dts/)
for the DTS file that will be used to produce the DTB linked into
the kernel.
config DMI
bool "Enable DMI scanning"
select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
default y
help
This enables SMBIOS/DMI feature for systems, and scanning of
DMI to identify machine quirks.
config EFI
bool "EFI runtime service support"
select UCS2_STRING
select EFI_RUNTIME_WRAPPERS
help
This enables the kernel to use EFI runtime services that are
available (such as the EFI variable services).
config EFI_STUB
bool "EFI boot stub support"
default y
depends on EFI
select EFI_GENERIC_STUB
help
This kernel feature allows the kernel to be loaded directly by
EFI firmware without the use of a bootloader.
config SCHED_SMT
bool "SMT scheduler support"
depends on SMP
default y
help
Improves scheduler's performance when there are multiple
threads in one physical core.
config SMP
bool "Multi-Processing support"
help
This enables support for systems with more than one CPU. If you have
a system with only one CPU, say N. If you have a system with more
than one CPU, say Y.
If you say N here, the kernel will run on uni- and multiprocessor
machines, but will use only one CPU of a multiprocessor machine. If
you say Y here, the kernel will run on many, but not all,
uniprocessor machines. On a uniprocessor machine, the kernel
will run faster if you say N here.
See also the SMP-HOWTO available at <http://www.tldp.org/docs.html#howto>.
If you don't know what to do here, say N.
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
depends on SMP
select GENERIC_IRQ_MIGRATION
help
Say Y here to allow turning CPUs off and on. CPUs can be
controlled through /sys/devices/system/cpu.
(Note: power management support will enable this option
automatically on SMP systems. )
Say N if you want to disable CPU hotplug.
config NR_CPUS
int "Maximum number of CPUs (2-256)"
range 2 256
depends on SMP
default "64"
help
This allows you to specify the maximum number of CPUs which this
kernel will support.
config NUMA
bool "NUMA Support"
select SMP
select ACPI_NUMA if ACPI
help
Say Y to compile the kernel with NUMA (Non-Uniform Memory Access)
support. This option improves performance on systems with more
than one NUMA node; on single node systems it is generally better
to leave it disabled.
config NODES_SHIFT
int
default "6"
depends on NUMA
config ARCH_FORCE_MAX_ORDER
int "Maximum zone order"
default "13" if PAGE_SIZE_64KB
default "11" if PAGE_SIZE_16KB
default "10"
help
The kernel memory allocator divides physically contiguous memory
blocks into "zones", where each zone is a power of two number of
pages. This option selects the largest power of two that the kernel
keeps in the memory allocator. If you need to allocate very large
blocks of physically contiguous memory, then you may need to
increase this value.
The page size is not necessarily 4KB. Keep this in mind
when choosing a value for this option.
config ARCH_IOREMAP
bool "Enable LoongArch DMW-based ioremap()"
help
We use generic TLB-based ioremap() by default since it has page
protection support. However, you can enable LoongArch DMW-based
ioremap() for better performance.
config ARCH_WRITECOMBINE
bool "Enable WriteCombine (WUC) for ioremap()"
help
LoongArch maintains cache coherency in hardware, but when paired
with LS7A chipsets the WUC attribute (Weak-ordered UnCached, which
is similar to WriteCombine) is out of the scope of cache coherency
machanism for PCIe devices (this is a PCIe protocol violation, which
may be fixed in newer chipsets).
This means WUC can only used for write-only memory regions now, so
this option is disabled by default, making WUC silently fallback to
SUC for ioremap(). You can enable this option if the kernel is ensured
to run on hardware without this bug.
You can override this setting via writecombine=on/off boot parameter.
config ARCH_STRICT_ALIGN
bool "Enable -mstrict-align to prevent unaligned accesses" if EXPERT
default y
help
Not all LoongArch cores support h/w unaligned access, we can use
-mstrict-align build parameter to prevent unaligned accesses.
CPUs with h/w unaligned access support:
Loongson-2K2000/2K3000/3A5000/3C5000/3D5000.
CPUs without h/w unaligned access support:
Loongson-2K500/2K1000.
This option is enabled by default to make the kernel be able to run
on all LoongArch systems. But you can disable it manually if you want
to run kernel only on systems with h/w unaligned access support in
order to optimise for performance.
config CPU_HAS_FPU
bool
default y
config CPU_HAS_LSX
bool "Support for the Loongson SIMD Extension"
depends on AS_HAS_LSX_EXTENSION
help
Loongson SIMD Extension (LSX) introduces 128 bit wide vector registers
and a set of SIMD instructions to operate on them. When this option
is enabled the kernel will support allocating & switching LSX
vector register contexts. If you know that your kernel will only be
running on CPUs which do not support LSX or that your userland will
not be making use of it then you may wish to say N here to reduce
the size & complexity of your kernel.
If unsure, say Y.
config CPU_HAS_LASX
bool "Support for the Loongson Advanced SIMD Extension"
depends on CPU_HAS_LSX
depends on AS_HAS_LASX_EXTENSION
help
Loongson Advanced SIMD Extension (LASX) introduces 256 bit wide vector
registers and a set of SIMD instructions to operate on them. When this
option is enabled the kernel will support allocating & switching LASX
vector register contexts. If you know that your kernel will only be
running on CPUs which do not support LASX or that your userland will
not be making use of it then you may wish to say N here to reduce
the size & complexity of your kernel.
If unsure, say Y.
config CPU_HAS_LBT
bool "Support for the Loongson Binary Translation Extension"
depends on AS_HAS_LBT_EXTENSION
help
Loongson Binary Translation (LBT) introduces 4 scratch registers (SCR0
to SCR3), x86/ARM eflags (eflags) and x87 fpu stack pointer (ftop).
Enabling this option allows the kernel to allocate and switch registers
specific to LBT.
If you want to use this feature, such as the Loongson Architecture
Translator (LAT), say Y.
config CPU_HAS_PREFETCH
bool
default y
config ARCH_SUPPORTS_KEXEC
def_bool y
config ARCH_SUPPORTS_CRASH_DUMP
def_bool y
config ARCH_SELECTS_CRASH_DUMP
def_bool y
depends on CRASH_DUMP
select RELOCATABLE
config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
def_bool CRASH_RESERVE
config RELOCATABLE
bool "Relocatable kernel"
help
This builds the kernel as a Position Independent Executable (PIE),
which retains all relocation metadata required, so as to relocate
the kernel binary at runtime to a different virtual address from
its link address.
config RANDOMIZE_BASE
bool "Randomize the address of the kernel (KASLR)"
depends on RELOCATABLE
help
Randomizes the physical and virtual address at which the
kernel image is loaded, as a security feature that
deters exploit attempts relying on knowledge of the location
of kernel internals.
The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET.
If unsure, say N.
config RANDOMIZE_BASE_MAX_OFFSET
hex "Maximum KASLR offset" if EXPERT
depends on RANDOMIZE_BASE
range 0x0 0x10000000
default "0x01000000"
help
When KASLR is active, this provides the maximum offset that will
be applied to the kernel image. It should be set according to the
amount of physical RAM available in the target system.
This is limited by the size of the lower address memory, 256MB.
source "kernel/livepatch/Kconfig"
endmenu
config ARCH_SELECT_MEMORY_MODEL
def_bool y
config ARCH_FLATMEM_ENABLE
def_bool y
depends on !NUMA
config ARCH_SPARSEMEM_ENABLE
def_bool y
select SPARSEMEM_VMEMMAP_ENABLE
help
Say Y to support efficient handling of sparse physical memory,
for architectures which are either NUMA (Non-Uniform Memory Access)
or have huge holes in the physical address space for other reasons.
See <file:Documentation/mm/numa.rst> for more.
config ARCH_MEMORY_PROBE
def_bool y
depends on MEMORY_HOTPLUG
config MMU
bool
default y
config ARCH_MMAP_RND_BITS_MIN
default 12
config ARCH_MMAP_RND_BITS_MAX
default 18
config ARCH_SUPPORTS_UPROBES
def_bool y
config KASAN_SHADOW_OFFSET
hex
default 0x0
depends on KASAN
menu "Power management options"
config ARCH_SUSPEND_POSSIBLE
def_bool y
config ARCH_HIBERNATION_POSSIBLE
def_bool y
source "kernel/power/Kconfig"
source "drivers/acpi/Kconfig"
endmenu
source "arch/loongarch/kvm/Kconfig"