linux/arch/riscv/Kconfig

# SPDX-License-Identifier: GPL-2.0-only
#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.rst.
#

config 64BIT
	bool

config 32BIT
	bool

config RISCV
	def_bool y
	# even on 32-bit, physical (and DMA) addresses are > 32-bits
	select PHYS_ADDR_T_64BIT
	select OF
	select OF_EARLY_FLATTREE
	select OF_IRQ
	select ARCH_HAS_BINFMT_FLAT
	select ARCH_WANT_FRAME_POINTERS
	select CLONE_BACKWARDS
	select COMMON_CLK
	select GENERIC_CLOCKEVENTS
	select GENERIC_CPU_DEVICES
	select GENERIC_IRQ_SHOW
	select GENERIC_PCI_IOMAP
	select GENERIC_SCHED_CLOCK
	select GENERIC_STRNCPY_FROM_USER if MMU
	select GENERIC_STRNLEN_USER if MMU
	select GENERIC_SMP_IDLE_THREAD
	select GENERIC_ATOMIC64 if !64BIT
	select GENERIC_IOREMAP
	select HAVE_ARCH_AUDITSYSCALL
	select HAVE_ARCH_SECCOMP_FILTER
	select HAVE_ASM_MODVERSIONS
	select HAVE_MEMBLOCK_NODE_MAP
	select HAVE_DMA_CONTIGUOUS if MMU
	select HAVE_FUTEX_CMPXCHG if FUTEX
	select HAVE_PERF_EVENTS
	select HAVE_PERF_REGS
	select HAVE_PERF_USER_STACK_DUMP
	select HAVE_SYSCALL_TRACEPOINTS
	select IRQ_DOMAIN
	select SPARSE_IRQ
	select SYSCTL_EXCEPTION_TRACE
	select HAVE_ARCH_TRACEHOOK
	select HAVE_PCI
	select MODULES_USE_ELF_RELA if MODULES
	select MODULE_SECTIONS if MODULES
	select THREAD_INFO_IN_TASK
	select PCI_DOMAINS_GENERIC if PCI
	select PCI_MSI if PCI
	select RISCV_TIMER
	select UACCESS_MEMCPY if !MMU
	select GENERIC_IRQ_MULTI_HANDLER
	select GENERIC_ARCH_TOPOLOGY if SMP
	select ARCH_HAS_PTE_SPECIAL
	select ARCH_HAS_MMIOWB
	select HAVE_EBPF_JIT if 64BIT
	select EDAC_SUPPORT
	select ARCH_HAS_GIGANTIC_PAGE
	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
	select SPARSEMEM_STATIC if 32BIT
	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
	select HAVE_ARCH_MMAP_RND_BITS if MMU

config ARCH_MMAP_RND_BITS_MIN
	default 18 if 64BIT
	default 8

# max bits determined by the following formula:
#  VA_BITS - PAGE_SHIFT - 3
config ARCH_MMAP_RND_BITS_MAX
	default 24 if 64BIT # SV39 based
	default 17

# set if we run in machine mode, cleared if we run in supervisor mode
config RISCV_M_MODE
	bool
	default !MMU

# set if we are running in S-mode and can use SBI calls
config RISCV_SBI
	bool
	depends on !RISCV_M_MODE
	default y

config MMU
	bool "MMU-based Paged Memory Management Support"
	default y
	help
	  Select if you want MMU-based virtualised addressing space
	  support by paged memory management. If unsure, say 'Y'.

config ZONE_DMA32
	bool
	default y if 64BIT

config VA_BITS
	int
	default 32 if 32BIT
	default 39 if 64BIT

config PA_BITS
	int
	default 34 if 32BIT
	default 56 if 64BIT

config PAGE_OFFSET
	hex
	default 0xC0000000 if 32BIT && MAXPHYSMEM_2GB
	default 0x80000000 if 64BIT && !MMU
	default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
	default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB

config ARCH_FLATMEM_ENABLE
	def_bool y

config ARCH_SPARSEMEM_ENABLE
	def_bool y
	select SPARSEMEM_VMEMMAP_ENABLE

config ARCH_SELECT_MEMORY_MODEL
	def_bool ARCH_SPARSEMEM_ENABLE

config ARCH_WANT_GENERAL_HUGETLB
	def_bool y

config SYS_SUPPORTS_HUGETLBFS
	def_bool y

config STACKTRACE_SUPPORT
	def_bool y

config TRACE_IRQFLAGS_SUPPORT
	def_bool y

config GENERIC_BUG
	def_bool y
	depends on BUG
	select GENERIC_BUG_RELATIVE_POINTERS if 64BIT

config GENERIC_BUG_RELATIVE_POINTERS
	bool

config GENERIC_CALIBRATE_DELAY
	def_bool y

config GENERIC_CSUM
	def_bool y

config GENERIC_HWEIGHT
	def_bool y

config FIX_EARLYCON_MEM
	def_bool CONFIG_MMU

config PGTABLE_LEVELS
	int
	default 3 if 64BIT
	default 2

source "arch/riscv/Kconfig.socs"

menu "Platform type"

choice
	prompt "Base ISA"
	default ARCH_RV64I
	help
	  This selects the base ISA that this kernel will target and must match
	  the target platform.

config ARCH_RV32I
	bool "RV32I"
	select 32BIT
	select GENERIC_LIB_ASHLDI3
	select GENERIC_LIB_ASHRDI3
	select GENERIC_LIB_LSHRDI3
	select GENERIC_LIB_UCMPDI2
	select MMU

config ARCH_RV64I
	bool "RV64I"
	select 64BIT
	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 && GCC_VERSION >= 50000
	select HAVE_FUNCTION_TRACER
	select HAVE_FUNCTION_GRAPH_TRACER
	select HAVE_FTRACE_MCOUNT_RECORD
	select HAVE_DYNAMIC_FTRACE if MMU
	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
	select SWIOTLB if MMU

endchoice

# We must be able to map all physical memory into the kernel, but the compiler
# is still a bit more efficient when generating code if it's setup in a manner
# such that it can only map 2GiB of memory.
choice
	prompt "Kernel Code Model"
	default CMODEL_MEDLOW if 32BIT
	default CMODEL_MEDANY if 64BIT

	config CMODEL_MEDLOW
		bool "medium low code model"
	config CMODEL_MEDANY
		bool "medium any code model"
endchoice

config MODULE_SECTIONS
	bool
	select HAVE_MOD_ARCH_SPECIFIC

choice
	prompt "Maximum Physical Memory"
	default MAXPHYSMEM_2GB if 32BIT
	default MAXPHYSMEM_2GB if 64BIT && CMODEL_MEDLOW
	default MAXPHYSMEM_128GB if 64BIT && CMODEL_MEDANY

	config MAXPHYSMEM_2GB
		bool "2GiB"
	config MAXPHYSMEM_128GB
		depends on 64BIT && CMODEL_MEDANY
		bool "128GiB"
endchoice


config SMP
	bool "Symmetric Multi-Processing"
	help
	  This enables support for systems with more than one CPU.  If
	  you say N here, the kernel will run on single 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, single processor machines. On a single
	  processor machine, the kernel will run faster if you say N
	  here.

	  If you don't know what to do here, say N.

config NR_CPUS
	int "Maximum number of CPUs (2-32)"
	range 2 32
	depends on SMP
	default "8"

choice
	prompt "CPU Tuning"
	default TUNE_GENERIC

config TUNE_GENERIC
	bool "generic"

endchoice

config RISCV_ISA_C
	bool "Emit compressed instructions when building Linux"
	default y
	help
	   Adds "C" to the ISA subsets that the toolchain is allowed to emit
	   when building Linux, which results in compressed instructions in the
	   Linux binary.

	   If you don't know what to do here, say Y.

menu "supported PMU type"
	depends on PERF_EVENTS

config RISCV_BASE_PMU
	bool "Base Performance Monitoring Unit"
	def_bool y
	help
	  A base PMU that serves as a reference implementation and has limited
	  feature of perf.  It can run on any RISC-V machines so serves as the
	  fallback, but this option can also be disable to reduce kernel size.

endmenu

config FPU
	bool "FPU support"
	default y
	help
	  Say N here if you want to disable all floating-point related procedure
	  in the kernel.

	  If you don't know what to do here, say Y.

endmenu

menu "Kernel features"

source "kernel/Kconfig.hz"

config SECCOMP
	bool "Enable seccomp to safely compute untrusted bytecode"
	help
	  This kernel feature is useful for number crunching applications
	  that may need to compute untrusted bytecode during their
	  execution. By using pipes or other transports made available to
	  the process as file descriptors supporting the read/write
	  syscalls, it's possible to isolate those applications in
	  their own address space using seccomp. Once seccomp is
	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
	  and the task is only allowed to execute a few safe syscalls
	  defined by each seccomp mode.

endmenu

menu "Boot options"

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 "Built-in command line usage" if CMDLINE != ""
	default CMDLINE_FALLBACK
	help
	  Choose how the kernel will handle the provided built-in command
	  line.

config CMDLINE_FALLBACK
	bool "Use bootloader kernel arguments if available"
	help
	  Use the built-in command line as fallback in case we get nothing
	  during boot. This is the default behaviour.

config CMDLINE_EXTEND
	bool "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 default 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

endmenu

menu "Power management options"

source "kernel/power/Kconfig"

endmenu