xref: /openbmc/linux/arch/riscv/Kconfig (revision fac59652993f075d57860769c99045b3ca18780d)
1 # SPDX-License-Identifier: GPL-2.0-only
2 #
3 # For a description of the syntax of this configuration file,
4 # see Documentation/kbuild/kconfig-language.rst.
5 #
6 
7 config 64BIT
8 	bool
9 
10 config 32BIT
11 	bool
12 
13 config RISCV
14 	def_bool y
15 	select ACPI_GENERIC_GSI if ACPI
16 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
17 	select ARCH_DMA_DEFAULT_COHERENT
18 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
19 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
20 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
21 	select ARCH_HAS_BINFMT_FLAT
22 	select ARCH_HAS_CURRENT_STACK_POINTER
23 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
24 	select ARCH_HAS_DEBUG_VM_PGTABLE
25 	select ARCH_HAS_DEBUG_WX
26 	select ARCH_HAS_FORTIFY_SOURCE
27 	select ARCH_HAS_GCOV_PROFILE_ALL
28 	select ARCH_HAS_GIGANTIC_PAGE
29 	select ARCH_HAS_KCOV
30 	select ARCH_HAS_MEMBARRIER_CALLBACKS
31 	select ARCH_HAS_MMIOWB
32 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
33 	select ARCH_HAS_PMEM_API
34 	select ARCH_HAS_PTE_SPECIAL
35 	select ARCH_HAS_SET_DIRECT_MAP if MMU
36 	select ARCH_HAS_SET_MEMORY if MMU
37 	select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
38 	select ARCH_HAS_STRICT_MODULE_RWX if MMU && !XIP_KERNEL
39 	select ARCH_HAS_SYSCALL_WRAPPER
40 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
41 	select ARCH_HAS_UBSAN_SANITIZE_ALL
42 	select ARCH_HAS_VDSO_DATA
43 	select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
44 	select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
45 	select ARCH_STACKWALK
46 	select ARCH_SUPPORTS_ATOMIC_RMW
47 	select ARCH_SUPPORTS_CFI_CLANG
48 	select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
49 	select ARCH_SUPPORTS_HUGETLBFS if MMU
50 	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
51 	select ARCH_SUPPORTS_PER_VMA_LOCK if MMU
52 	select ARCH_USE_MEMTEST
53 	select ARCH_USE_QUEUED_RWLOCKS
54 	select ARCH_USES_CFI_TRAPS if CFI_CLANG
55 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
56 	select ARCH_WANT_FRAME_POINTERS
57 	select ARCH_WANT_GENERAL_HUGETLB if !RISCV_ISA_SVNAPOT
58 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
59 	select ARCH_WANT_LD_ORPHAN_WARN if !XIP_KERNEL
60 	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
61 	select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
62 	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
63 	select BUILDTIME_TABLE_SORT if MMU
64 	select CLINT_TIMER if !MMU
65 	select CLONE_BACKWARDS
66 	select COMMON_CLK
67 	select CPU_PM if CPU_IDLE || HIBERNATION
68 	select EDAC_SUPPORT
69 	select FRAME_POINTER if PERF_EVENTS || (FUNCTION_TRACER && !DYNAMIC_FTRACE)
70 	select GENERIC_ARCH_TOPOLOGY
71 	select GENERIC_ATOMIC64 if !64BIT
72 	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
73 	select GENERIC_EARLY_IOREMAP
74 	select GENERIC_ENTRY
75 	select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
76 	select GENERIC_IDLE_POLL_SETUP
77 	select GENERIC_IOREMAP if MMU
78 	select GENERIC_IRQ_IPI if SMP
79 	select GENERIC_IRQ_IPI_MUX if SMP
80 	select GENERIC_IRQ_MULTI_HANDLER
81 	select GENERIC_IRQ_SHOW
82 	select GENERIC_IRQ_SHOW_LEVEL
83 	select GENERIC_LIB_DEVMEM_IS_ALLOWED
84 	select GENERIC_PCI_IOMAP
85 	select GENERIC_PTDUMP if MMU
86 	select GENERIC_SCHED_CLOCK
87 	select GENERIC_SMP_IDLE_THREAD
88 	select GENERIC_TIME_VSYSCALL if MMU && 64BIT
89 	select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
90 	select HARDIRQS_SW_RESEND
91 	select HAS_IOPORT if MMU
92 	select HAVE_ARCH_AUDITSYSCALL
93 	select HAVE_ARCH_HUGE_VMALLOC if HAVE_ARCH_HUGE_VMAP
94 	select HAVE_ARCH_HUGE_VMAP if MMU && 64BIT && !XIP_KERNEL
95 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
96 	select HAVE_ARCH_JUMP_LABEL_RELATIVE if !XIP_KERNEL
97 	select HAVE_ARCH_KASAN if MMU && 64BIT
98 	select HAVE_ARCH_KASAN_VMALLOC if MMU && 64BIT
99 	select HAVE_ARCH_KFENCE if MMU && 64BIT
100 	select HAVE_ARCH_KGDB if !XIP_KERNEL
101 	select HAVE_ARCH_KGDB_QXFER_PKT
102 	select HAVE_ARCH_MMAP_RND_BITS if MMU
103 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
104 	select HAVE_ARCH_SECCOMP_FILTER
105 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
106 	select HAVE_ARCH_TRACEHOOK
107 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
108 	select HAVE_ARCH_USERFAULTFD_MINOR if 64BIT && USERFAULTFD
109 	select HAVE_ARCH_VMAP_STACK if MMU && 64BIT
110 	select HAVE_ASM_MODVERSIONS
111 	select HAVE_CONTEXT_TRACKING_USER
112 	select HAVE_DEBUG_KMEMLEAK
113 	select HAVE_DMA_CONTIGUOUS if MMU
114 	select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
115 	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
116 	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
117 	select HAVE_FUNCTION_GRAPH_TRACER
118 	select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
119 	select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION
120 	select HAVE_EBPF_JIT if MMU
121 	select HAVE_FUNCTION_ARG_ACCESS_API
122 	select HAVE_FUNCTION_ERROR_INJECTION
123 	select HAVE_GCC_PLUGINS
124 	select HAVE_GENERIC_VDSO if MMU && 64BIT
125 	select HAVE_IRQ_TIME_ACCOUNTING
126 	select HAVE_KPROBES if !XIP_KERNEL
127 	select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL
128 	select HAVE_KRETPROBES if !XIP_KERNEL
129 	# https://github.com/ClangBuiltLinux/linux/issues/1881
130 	select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if !LD_IS_LLD
131 	select HAVE_MOVE_PMD
132 	select HAVE_MOVE_PUD
133 	select HAVE_PCI
134 	select HAVE_PERF_EVENTS
135 	select HAVE_PERF_REGS
136 	select HAVE_PERF_USER_STACK_DUMP
137 	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
138 	select HAVE_PREEMPT_DYNAMIC_KEY if !XIP_KERNEL
139 	select HAVE_REGS_AND_STACK_ACCESS_API
140 	select HAVE_RETHOOK if !XIP_KERNEL
141 	select HAVE_RSEQ
142 	select HAVE_STACKPROTECTOR
143 	select HAVE_SYSCALL_TRACEPOINTS
144 	select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
145 	select IRQ_DOMAIN
146 	select IRQ_FORCED_THREADING
147 	select KASAN_VMALLOC if KASAN
148 	select LOCK_MM_AND_FIND_VMA
149 	select MODULES_USE_ELF_RELA if MODULES
150 	select MODULE_SECTIONS if MODULES
151 	select OF
152 	select OF_EARLY_FLATTREE
153 	select OF_IRQ
154 	select PCI_DOMAINS_GENERIC if PCI
155 	select PCI_MSI if PCI
156 	select RISCV_ALTERNATIVE if !XIP_KERNEL
157 	select RISCV_INTC
158 	select RISCV_TIMER if RISCV_SBI
159 	select SIFIVE_PLIC
160 	select SPARSE_IRQ
161 	select SYSCTL_EXCEPTION_TRACE
162 	select THREAD_INFO_IN_TASK
163 	select TRACE_IRQFLAGS_SUPPORT
164 	select UACCESS_MEMCPY if !MMU
165 	select ZONE_DMA32 if 64BIT
166 
167 config CLANG_SUPPORTS_DYNAMIC_FTRACE
168 	def_bool CC_IS_CLANG
169 	# https://github.com/llvm/llvm-project/commit/6ab8927931851bb42b2c93a00801dc499d7d9b1e
170 	depends on CLANG_VERSION >= 130000
171 	# https://github.com/ClangBuiltLinux/linux/issues/1817
172 	depends on AS_IS_GNU || (AS_IS_LLVM && (LD_IS_LLD || LD_VERSION >= 23600))
173 
174 config GCC_SUPPORTS_DYNAMIC_FTRACE
175 	def_bool CC_IS_GCC
176 	depends on $(cc-option,-fpatchable-function-entry=8)
177 
178 config ARCH_MMAP_RND_BITS_MIN
179 	default 18 if 64BIT
180 	default 8
181 
182 config ARCH_MMAP_RND_COMPAT_BITS_MIN
183 	default 8
184 
185 # max bits determined by the following formula:
186 #  VA_BITS - PAGE_SHIFT - 3
187 config ARCH_MMAP_RND_BITS_MAX
188 	default 24 if 64BIT # SV39 based
189 	default 17
190 
191 config ARCH_MMAP_RND_COMPAT_BITS_MAX
192 	default 17
193 
194 # set if we run in machine mode, cleared if we run in supervisor mode
195 config RISCV_M_MODE
196 	bool
197 	default !MMU
198 
199 # set if we are running in S-mode and can use SBI calls
200 config RISCV_SBI
201 	bool
202 	depends on !RISCV_M_MODE
203 	default y
204 
205 config MMU
206 	bool "MMU-based Paged Memory Management Support"
207 	default y
208 	help
209 	  Select if you want MMU-based virtualised addressing space
210 	  support by paged memory management. If unsure, say 'Y'.
211 
212 config PAGE_OFFSET
213 	hex
214 	default 0xC0000000 if 32BIT && MMU
215 	default 0x80000000 if !MMU
216 	default 0xff60000000000000 if 64BIT
217 
218 config KASAN_SHADOW_OFFSET
219 	hex
220 	depends on KASAN_GENERIC
221 	default 0xdfffffff00000000 if 64BIT
222 	default 0xffffffff if 32BIT
223 
224 config ARCH_FLATMEM_ENABLE
225 	def_bool !NUMA
226 
227 config ARCH_SPARSEMEM_ENABLE
228 	def_bool y
229 	depends on MMU
230 	select SPARSEMEM_STATIC if 32BIT && SPARSEMEM
231 	select SPARSEMEM_VMEMMAP_ENABLE if 64BIT
232 
233 config ARCH_SELECT_MEMORY_MODEL
234 	def_bool ARCH_SPARSEMEM_ENABLE
235 
236 config ARCH_SUPPORTS_UPROBES
237 	def_bool y
238 
239 config STACKTRACE_SUPPORT
240 	def_bool y
241 
242 config GENERIC_BUG
243 	def_bool y
244 	depends on BUG
245 	select GENERIC_BUG_RELATIVE_POINTERS if 64BIT
246 
247 config GENERIC_BUG_RELATIVE_POINTERS
248 	bool
249 
250 config GENERIC_CALIBRATE_DELAY
251 	def_bool y
252 
253 config GENERIC_CSUM
254 	def_bool y
255 
256 config GENERIC_HWEIGHT
257 	def_bool y
258 
259 config FIX_EARLYCON_MEM
260 	def_bool MMU
261 
262 config ILLEGAL_POINTER_VALUE
263 	hex
264 	default 0 if 32BIT
265 	default 0xdead000000000000 if 64BIT
266 
267 config PGTABLE_LEVELS
268 	int
269 	default 5 if 64BIT
270 	default 2
271 
272 config LOCKDEP_SUPPORT
273 	def_bool y
274 
275 config RISCV_DMA_NONCOHERENT
276 	bool
277 	select ARCH_HAS_DMA_PREP_COHERENT
278 	select ARCH_HAS_SETUP_DMA_OPS
279 	select ARCH_HAS_SYNC_DMA_FOR_CPU
280 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
281 	select DMA_BOUNCE_UNALIGNED_KMALLOC if SWIOTLB
282 
283 config RISCV_NONSTANDARD_CACHE_OPS
284 	bool
285 	help
286 	  This enables function pointer support for non-standard noncoherent
287 	  systems to handle cache management.
288 
289 config AS_HAS_INSN
290 	def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) t0$(comma) t0$(comma) zero)
291 
292 config AS_HAS_OPTION_ARCH
293 	# https://reviews.llvm.org/D123515
294 	def_bool y
295 	depends on $(as-instr, .option arch$(comma) +m)
296 
297 source "arch/riscv/Kconfig.socs"
298 source "arch/riscv/Kconfig.errata"
299 
300 menu "Platform type"
301 
302 config NONPORTABLE
303 	bool "Allow configurations that result in non-portable kernels"
304 	help
305 	  RISC-V kernel binaries are compatible between all known systems
306 	  whenever possible, but there are some use cases that can only be
307 	  satisfied by configurations that result in kernel binaries that are
308 	  not portable between systems.
309 
310 	  Selecting N does not guarantee kernels will be portable to all known
311 	  systems.  Selecting any of the options guarded by NONPORTABLE will
312 	  result in kernel binaries that are unlikely to be portable between
313 	  systems.
314 
315 	  If unsure, say N.
316 
317 choice
318 	prompt "Base ISA"
319 	default ARCH_RV64I
320 	help
321 	  This selects the base ISA that this kernel will target and must match
322 	  the target platform.
323 
324 config ARCH_RV32I
325 	bool "RV32I"
326 	depends on NONPORTABLE
327 	select 32BIT
328 	select GENERIC_LIB_ASHLDI3
329 	select GENERIC_LIB_ASHRDI3
330 	select GENERIC_LIB_LSHRDI3
331 	select GENERIC_LIB_UCMPDI2
332 
333 config ARCH_RV64I
334 	bool "RV64I"
335 	select 64BIT
336 	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
337 	select SWIOTLB if MMU
338 
339 endchoice
340 
341 # We must be able to map all physical memory into the kernel, but the compiler
342 # is still a bit more efficient when generating code if it's setup in a manner
343 # such that it can only map 2GiB of memory.
344 choice
345 	prompt "Kernel Code Model"
346 	default CMODEL_MEDLOW if 32BIT
347 	default CMODEL_MEDANY if 64BIT
348 
349 	config CMODEL_MEDLOW
350 		bool "medium low code model"
351 	config CMODEL_MEDANY
352 		bool "medium any code model"
353 endchoice
354 
355 config MODULE_SECTIONS
356 	bool
357 	select HAVE_MOD_ARCH_SPECIFIC
358 
359 config SMP
360 	bool "Symmetric Multi-Processing"
361 	help
362 	  This enables support for systems with more than one CPU.  If
363 	  you say N here, the kernel will run on single and
364 	  multiprocessor machines, but will use only one CPU of a
365 	  multiprocessor machine. If you say Y here, the kernel will run
366 	  on many, but not all, single processor machines. On a single
367 	  processor machine, the kernel will run faster if you say N
368 	  here.
369 
370 	  If you don't know what to do here, say N.
371 
372 config SCHED_MC
373 	bool "Multi-core scheduler support"
374 	depends on SMP
375 	help
376 	  Multi-core scheduler support improves the CPU scheduler's decision
377 	  making when dealing with multi-core CPU chips at a cost of slightly
378 	  increased overhead in some places. If unsure say N here.
379 
380 config NR_CPUS
381 	int "Maximum number of CPUs (2-512)"
382 	depends on SMP
383 	range 2 512 if !RISCV_SBI_V01
384 	range 2 32 if RISCV_SBI_V01 && 32BIT
385 	range 2 64 if RISCV_SBI_V01 && 64BIT
386 	default "32" if 32BIT
387 	default "64" if 64BIT
388 
389 config HOTPLUG_CPU
390 	bool "Support for hot-pluggable CPUs"
391 	depends on SMP
392 	select GENERIC_IRQ_MIGRATION
393 	help
394 
395 	  Say Y here to experiment with turning CPUs off and on.  CPUs
396 	  can be controlled through /sys/devices/system/cpu.
397 
398 	  Say N if you want to disable CPU hotplug.
399 
400 choice
401 	prompt "CPU Tuning"
402 	default TUNE_GENERIC
403 
404 config TUNE_GENERIC
405 	bool "generic"
406 
407 endchoice
408 
409 # Common NUMA Features
410 config NUMA
411 	bool "NUMA Memory Allocation and Scheduler Support"
412 	depends on SMP && MMU
413 	select ARCH_SUPPORTS_NUMA_BALANCING
414 	select GENERIC_ARCH_NUMA
415 	select NEED_PER_CPU_EMBED_FIRST_CHUNK
416 	select OF_NUMA
417 	select USE_PERCPU_NUMA_NODE_ID
418 	help
419 	  Enable NUMA (Non-Uniform Memory Access) support.
420 
421 	  The kernel will try to allocate memory used by a CPU on the
422 	  local memory of the CPU and add some more NUMA awareness to the kernel.
423 
424 config NODES_SHIFT
425 	int "Maximum NUMA Nodes (as a power of 2)"
426 	range 1 10
427 	default "2"
428 	depends on NUMA
429 	help
430 	  Specify the maximum number of NUMA Nodes available on the target
431 	  system.  Increases memory reserved to accommodate various tables.
432 
433 config RISCV_ALTERNATIVE
434 	bool
435 	depends on !XIP_KERNEL
436 	help
437 	  This Kconfig allows the kernel to automatically patch the
438 	  erratum or cpufeature required by the execution platform at run
439 	  time. The code patching overhead is minimal, as it's only done
440 	  once at boot and once on each module load.
441 
442 config RISCV_ALTERNATIVE_EARLY
443 	bool
444 	depends on RISCV_ALTERNATIVE
445 	help
446 	  Allows early patching of the kernel for special errata
447 
448 config RISCV_ISA_C
449 	bool "Emit compressed instructions when building Linux"
450 	default y
451 	help
452 	  Adds "C" to the ISA subsets that the toolchain is allowed to emit
453 	  when building Linux, which results in compressed instructions in the
454 	  Linux binary.
455 
456 	  If you don't know what to do here, say Y.
457 
458 config RISCV_ISA_SVNAPOT
459 	bool "Svnapot extension support for supervisor mode NAPOT pages"
460 	depends on 64BIT && MMU
461 	depends on RISCV_ALTERNATIVE
462 	default y
463 	help
464 	  Allow kernel to detect the Svnapot ISA-extension dynamically at boot
465 	  time and enable its usage.
466 
467 	  The Svnapot extension is used to mark contiguous PTEs as a range
468 	  of contiguous virtual-to-physical translations for a naturally
469 	  aligned power-of-2 (NAPOT) granularity larger than the base 4KB page
470 	  size. When HUGETLBFS is also selected this option unconditionally
471 	  allocates some memory for each NAPOT page size supported by the kernel.
472 	  When optimizing for low memory consumption and for platforms without
473 	  the Svnapot extension, it may be better to say N here.
474 
475 	  If you don't know what to do here, say Y.
476 
477 config RISCV_ISA_SVPBMT
478 	bool "Svpbmt extension support for supervisor mode page-based memory types"
479 	depends on 64BIT && MMU
480 	depends on RISCV_ALTERNATIVE
481 	default y
482 	help
483 	   Adds support to dynamically detect the presence of the Svpbmt
484 	   ISA-extension (Supervisor-mode: page-based memory types) and
485 	   enable its usage.
486 
487 	   The memory type for a page contains a combination of attributes
488 	   that indicate the cacheability, idempotency, and ordering
489 	   properties for access to that page.
490 
491 	   The Svpbmt extension is only available on 64-bit cpus.
492 
493 	   If you don't know what to do here, say Y.
494 
495 config TOOLCHAIN_HAS_V
496 	bool
497 	default y
498 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64imv)
499 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32imv)
500 	depends on LLD_VERSION >= 140000 || LD_VERSION >= 23800
501 	depends on AS_HAS_OPTION_ARCH
502 
503 config RISCV_ISA_V
504 	bool "VECTOR extension support"
505 	depends on TOOLCHAIN_HAS_V
506 	depends on FPU
507 	select DYNAMIC_SIGFRAME
508 	default y
509 	help
510 	  Say N here if you want to disable all vector related procedure
511 	  in the kernel.
512 
513 	  If you don't know what to do here, say Y.
514 
515 config RISCV_ISA_V_DEFAULT_ENABLE
516 	bool "Enable userspace Vector by default"
517 	depends on RISCV_ISA_V
518 	default y
519 	help
520 	  Say Y here if you want to enable Vector in userspace by default.
521 	  Otherwise, userspace has to make explicit prctl() call to enable
522 	  Vector, or enable it via the sysctl interface.
523 
524 	  If you don't know what to do here, say Y.
525 
526 config TOOLCHAIN_HAS_ZBB
527 	bool
528 	default y
529 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbb)
530 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb)
531 	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
532 	depends on AS_HAS_OPTION_ARCH
533 
534 config RISCV_ISA_ZBB
535 	bool "Zbb extension support for bit manipulation instructions"
536 	depends on TOOLCHAIN_HAS_ZBB
537 	depends on MMU
538 	depends on RISCV_ALTERNATIVE
539 	default y
540 	help
541 	   Adds support to dynamically detect the presence of the ZBB
542 	   extension (basic bit manipulation) and enable its usage.
543 
544 	   The Zbb extension provides instructions to accelerate a number
545 	   of bit-specific operations (count bit population, sign extending,
546 	   bitrotation, etc).
547 
548 	   If you don't know what to do here, say Y.
549 
550 config RISCV_ISA_ZICBOM
551 	bool "Zicbom extension support for non-coherent DMA operation"
552 	depends on MMU
553 	depends on RISCV_ALTERNATIVE
554 	default y
555 	select RISCV_DMA_NONCOHERENT
556 	select DMA_DIRECT_REMAP
557 	help
558 	   Adds support to dynamically detect the presence of the ZICBOM
559 	   extension (Cache Block Management Operations) and enable its
560 	   usage.
561 
562 	   The Zicbom extension can be used to handle for example
563 	   non-coherent DMA support on devices that need it.
564 
565 	   If you don't know what to do here, say Y.
566 
567 config RISCV_ISA_ZICBOZ
568 	bool "Zicboz extension support for faster zeroing of memory"
569 	depends on MMU
570 	depends on RISCV_ALTERNATIVE
571 	default y
572 	help
573 	   Enable the use of the Zicboz extension (cbo.zero instruction)
574 	   when available.
575 
576 	   The Zicboz extension is used for faster zeroing of memory.
577 
578 	   If you don't know what to do here, say Y.
579 
580 config TOOLCHAIN_HAS_ZIHINTPAUSE
581 	bool
582 	default y
583 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zihintpause)
584 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zihintpause)
585 	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23600
586 
587 config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
588 	def_bool y
589 	# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
590 	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
591 	depends on AS_IS_GNU && AS_VERSION >= 23600
592 	help
593 	  Binutils-2.38 and GCC-12.1.0 bumped the default ISA spec to the newer
594 	  20191213 version, which moves some instructions from the I extension to
595 	  the Zicsr and Zifencei extensions. This requires explicitly specifying
596 	  Zicsr and Zifencei when binutils >= 2.38 or GCC >= 12.1.0. Zicsr
597 	  and Zifencei are supported in binutils from version 2.36 onwards.
598 	  To make life easier, and avoid forcing toolchains that default to a
599 	  newer ISA spec to version 2.2, relax the check to binutils >= 2.36.
600 	  For clang < 17 or GCC < 11.3.0, for which this is not possible or need
601 	  special treatment, this is dealt with in TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
602 
603 config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
604 	def_bool y
605 	depends on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
606 	# https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
607 	# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=d29f5d6ab513c52fd872f532c492e35ae9fd6671
608 	depends on (CC_IS_CLANG && CLANG_VERSION < 170000) || (CC_IS_GCC && GCC_VERSION < 110300)
609 	help
610 	  Certain versions of clang and GCC do not support zicsr and zifencei via
611 	  -march. This option causes an older ISA spec compatible with these older
612 	  versions of clang and GCC to be passed to GAS, which has the same result
613 	  as passing zicsr and zifencei to -march.
614 
615 config FPU
616 	bool "FPU support"
617 	default y
618 	help
619 	  Say N here if you want to disable all floating-point related procedure
620 	  in the kernel.
621 
622 	  If you don't know what to do here, say Y.
623 
624 config IRQ_STACKS
625 	bool "Independent irq & softirq stacks" if EXPERT
626 	default y
627 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
628 	select HAVE_SOFTIRQ_ON_OWN_STACK
629 	help
630 	  Add independent irq & softirq stacks for percpu to prevent kernel stack
631 	  overflows. We may save some memory footprint by disabling IRQ_STACKS.
632 
633 config THREAD_SIZE_ORDER
634 	int "Kernel stack size (in power-of-two numbers of page size)" if VMAP_STACK && EXPERT
635 	range 0 4
636 	default 1 if 32BIT
637 	default 2
638 	help
639 	  Specify the Pages of thread stack size (from 4KB to 64KB), which also
640 	  affects irq stack size, which is equal to thread stack size.
641 
642 endmenu # "Platform type"
643 
644 menu "Kernel features"
645 
646 source "kernel/Kconfig.hz"
647 
648 config RISCV_SBI_V01
649 	bool "SBI v0.1 support"
650 	depends on RISCV_SBI
651 	help
652 	  This config allows kernel to use SBI v0.1 APIs. This will be
653 	  deprecated in future once legacy M-mode software are no longer in use.
654 
655 config RISCV_BOOT_SPINWAIT
656 	bool "Spinwait booting method"
657 	depends on SMP
658 	default y if RISCV_SBI_V01 || RISCV_M_MODE
659 	help
660 	  This enables support for booting Linux via spinwait method. In the
661 	  spinwait method, all cores randomly jump to Linux. One of the cores
662 	  gets chosen via lottery and all other keep spinning on a percpu
663 	  variable. This method cannot support CPU hotplug and sparse hartid
664 	  scheme. It should be only enabled for M-mode Linux or platforms relying
665 	  on older firmware without SBI HSM extension. All other platforms should
666 	  rely on ordered booting via SBI HSM extension which gets chosen
667 	  dynamically at runtime if the firmware supports it.
668 
669 	  Since spinwait is incompatible with sparse hart IDs, it requires
670 	  NR_CPUS be large enough to contain the physical hart ID of the first
671 	  hart to enter Linux.
672 
673 	  If unsure what to do here, say N.
674 
675 config ARCH_SUPPORTS_KEXEC
676 	def_bool y
677 
678 config ARCH_SELECTS_KEXEC
679 	def_bool y
680 	depends on KEXEC
681 	select HOTPLUG_CPU if SMP
682 
683 config ARCH_SUPPORTS_KEXEC_FILE
684 	def_bool 64BIT
685 
686 config ARCH_SELECTS_KEXEC_FILE
687 	def_bool y
688 	depends on KEXEC_FILE
689 	select HAVE_IMA_KEXEC if IMA
690 	select KEXEC_ELF
691 
692 config ARCH_SUPPORTS_KEXEC_PURGATORY
693 	def_bool ARCH_SUPPORTS_KEXEC_FILE
694 
695 config ARCH_SUPPORTS_CRASH_DUMP
696 	def_bool y
697 
698 config COMPAT
699 	bool "Kernel support for 32-bit U-mode"
700 	default 64BIT
701 	depends on 64BIT && MMU
702 	help
703 	  This option enables support for a 32-bit U-mode running under a 64-bit
704 	  kernel at S-mode. riscv32-specific components such as system calls,
705 	  the user helper functions (vdso), signal rt_frame functions and the
706 	  ptrace interface are handled appropriately by the kernel.
707 
708 	  If you want to execute 32-bit userspace applications, say Y.
709 
710 config RELOCATABLE
711 	bool "Build a relocatable kernel"
712 	depends on MMU && 64BIT && !XIP_KERNEL
713 	help
714           This builds a kernel as a Position Independent Executable (PIE),
715           which retains all relocation metadata required to relocate the
716           kernel binary at runtime to a different virtual address than the
717           address it was linked at.
718           Since RISCV uses the RELA relocation format, this requires a
719           relocation pass at runtime even if the kernel is loaded at the
720           same address it was linked at.
721 
722           If unsure, say N.
723 
724 config RANDOMIZE_BASE
725         bool "Randomize the address of the kernel image"
726         select RELOCATABLE
727         depends on MMU && 64BIT && !XIP_KERNEL
728         help
729           Randomizes the virtual address at which the kernel image is
730           loaded, as a security feature that deters exploit attempts
731           relying on knowledge of the location of kernel internals.
732 
733           It is the bootloader's job to provide entropy, by passing a
734           random u64 value in /chosen/kaslr-seed at kernel entry.
735 
736           When booting via the UEFI stub, it will invoke the firmware's
737           EFI_RNG_PROTOCOL implementation (if available) to supply entropy
738           to the kernel proper. In addition, it will randomise the physical
739           location of the kernel Image as well.
740 
741           If unsure, say N.
742 
743 endmenu # "Kernel features"
744 
745 menu "Boot options"
746 
747 config CMDLINE
748 	string "Built-in kernel command line"
749 	help
750 	  For most platforms, the arguments for the kernel's command line
751 	  are provided at run-time, during boot. However, there are cases
752 	  where either no arguments are being provided or the provided
753 	  arguments are insufficient or even invalid.
754 
755 	  When that occurs, it is possible to define a built-in command
756 	  line here and choose how the kernel should use it later on.
757 
758 choice
759 	prompt "Built-in command line usage" if CMDLINE != ""
760 	default CMDLINE_FALLBACK
761 	help
762 	  Choose how the kernel will handle the provided built-in command
763 	  line.
764 
765 config CMDLINE_FALLBACK
766 	bool "Use bootloader kernel arguments if available"
767 	help
768 	  Use the built-in command line as fallback in case we get nothing
769 	  during boot. This is the default behaviour.
770 
771 config CMDLINE_EXTEND
772 	bool "Extend bootloader kernel arguments"
773 	help
774 	  The command-line arguments provided during boot will be
775 	  appended to the built-in command line. This is useful in
776 	  cases where the provided arguments are insufficient and
777 	  you don't want to or cannot modify them.
778 
779 config CMDLINE_FORCE
780 	bool "Always use the default kernel command string"
781 	help
782 	  Always use the built-in command line, even if we get one during
783 	  boot. This is useful in case you need to override the provided
784 	  command line on systems where you don't have or want control
785 	  over it.
786 
787 endchoice
788 
789 config EFI_STUB
790 	bool
791 
792 config EFI
793 	bool "UEFI runtime support"
794 	depends on OF && !XIP_KERNEL
795 	depends on MMU
796 	default y
797 	select ARCH_SUPPORTS_ACPI if 64BIT
798 	select EFI_GENERIC_STUB
799 	select EFI_PARAMS_FROM_FDT
800 	select EFI_RUNTIME_WRAPPERS
801 	select EFI_STUB
802 	select LIBFDT
803 	select RISCV_ISA_C
804 	select UCS2_STRING
805 	help
806 	  This option provides support for runtime services provided
807 	  by UEFI firmware (such as non-volatile variables, realtime
808 	  clock, and platform reset). A UEFI stub is also provided to
809 	  allow the kernel to be booted as an EFI application. This
810 	  is only useful on systems that have UEFI firmware.
811 
812 config CC_HAVE_STACKPROTECTOR_TLS
813 	def_bool $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=tp -mstack-protector-guard-offset=0)
814 
815 config STACKPROTECTOR_PER_TASK
816 	def_bool y
817 	depends on !RANDSTRUCT
818 	depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS
819 
820 config PHYS_RAM_BASE_FIXED
821 	bool "Explicitly specified physical RAM address"
822 	depends on NONPORTABLE
823 	default n
824 
825 config PHYS_RAM_BASE
826 	hex "Platform Physical RAM address"
827 	depends on PHYS_RAM_BASE_FIXED
828 	default "0x80000000"
829 	help
830 	  This is the physical address of RAM in the system. It has to be
831 	  explicitly specified to run early relocations of read-write data
832 	  from flash to RAM.
833 
834 config XIP_KERNEL
835 	bool "Kernel Execute-In-Place from ROM"
836 	depends on MMU && SPARSEMEM && NONPORTABLE
837 	# This prevents XIP from being enabled by all{yes,mod}config, which
838 	# fail to build since XIP doesn't support large kernels.
839 	depends on !COMPILE_TEST
840 	select PHYS_RAM_BASE_FIXED
841 	help
842 	  Execute-In-Place allows the kernel to run from non-volatile storage
843 	  directly addressable by the CPU, such as NOR flash. This saves RAM
844 	  space since the text section of the kernel is not loaded from flash
845 	  to RAM.  Read-write sections, such as the data section and stack,
846 	  are still copied to RAM.  The XIP kernel is not compressed since
847 	  it has to run directly from flash, so it will take more space to
848 	  store it.  The flash address used to link the kernel object files,
849 	  and for storing it, is configuration dependent. Therefore, if you
850 	  say Y here, you must know the proper physical address where to
851 	  store the kernel image depending on your own flash memory usage.
852 
853 	  Also note that the make target becomes "make xipImage" rather than
854 	  "make zImage" or "make Image".  The final kernel binary to put in
855 	  ROM memory will be arch/riscv/boot/xipImage.
856 
857 	  SPARSEMEM is required because the kernel text and rodata that are
858 	  flash resident are not backed by memmap, then any attempt to get
859 	  a struct page on those regions will trigger a fault.
860 
861 	  If unsure, say N.
862 
863 config XIP_PHYS_ADDR
864 	hex "XIP Kernel Physical Location"
865 	depends on XIP_KERNEL
866 	default "0x21000000"
867 	help
868 	  This is the physical address in your flash memory the kernel will
869 	  be linked for and stored to.  This address is dependent on your
870 	  own flash usage.
871 
872 config RISCV_ISA_FALLBACK
873 	bool "Permit falling back to parsing riscv,isa for extension support by default"
874 	default y
875 	help
876 	  Parsing the "riscv,isa" devicetree property has been deprecated and
877 	  replaced by a list of explicitly defined strings. For compatibility
878 	  with existing platforms, the kernel will fall back to parsing the
879 	  "riscv,isa" property if the replacements are not found.
880 
881 	  Selecting N here will result in a kernel that does not use the
882 	  fallback, unless the commandline "riscv_isa_fallback" parameter is
883 	  present.
884 
885 	  Please see the dt-binding, located at
886 	  Documentation/devicetree/bindings/riscv/extensions.yaml for details
887 	  on the replacement properties, "riscv,isa-base" and
888 	  "riscv,isa-extensions".
889 
890 endmenu # "Boot options"
891 
892 config BUILTIN_DTB
893 	bool
894 	depends on OF && NONPORTABLE
895 	default y if XIP_KERNEL
896 
897 config PORTABLE
898 	bool
899 	default !NONPORTABLE
900 	select EFI
901 	select MMU
902 	select OF
903 
904 menu "Power management options"
905 
906 source "kernel/power/Kconfig"
907 
908 # Hibernation is only possible on systems where the SBI implementation has
909 # marked its reserved memory as not accessible from, or does not run
910 # from the same memory as, Linux
911 config ARCH_HIBERNATION_POSSIBLE
912 	def_bool NONPORTABLE
913 
914 config ARCH_HIBERNATION_HEADER
915 	def_bool HIBERNATION
916 
917 config ARCH_SUSPEND_POSSIBLE
918 	def_bool y
919 
920 endmenu # "Power management options"
921 
922 menu "CPU Power Management"
923 
924 source "drivers/cpuidle/Kconfig"
925 
926 source "drivers/cpufreq/Kconfig"
927 
928 endmenu # "CPU Power Management"
929 
930 source "arch/riscv/kvm/Kconfig"
931 
932 source "drivers/acpi/Kconfig"
933