arch/s390/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0
   2 config MMU
   3         def_bool y
   4
   5 config CPU_BIG_ENDIAN
   6         def_bool y
   7
   8 config LOCKDEP_SUPPORT
   9         def_bool y
  10
  11 config STACKTRACE_SUPPORT
  12         def_bool y
  13
  14 config ARCH_HAS_ILOG2_U32
  15         def_bool n
  16
  17 config ARCH_HAS_ILOG2_U64
  18         def_bool n
  19
  20 config GENERIC_HWEIGHT
  21         def_bool y
  22
  23 config GENERIC_BUG
  24         def_bool y if BUG
  25
  26 config GENERIC_BUG_RELATIVE_POINTERS
  27         def_bool y
  28
  29 config GENERIC_LOCKBREAK
  30         def_bool y if PREEMPTION
  31
  32 config PGSTE
  33         def_bool y if KVM
  34
  35 config AUDIT_ARCH
  36         def_bool y
  37
  38 config NO_IOPORT_MAP
  39         def_bool y
  40
  41 config PCI_QUIRKS
  42         def_bool n
  43
  44 config ARCH_SUPPORTS_UPROBES
  45         def_bool y
  46
  47 config KASAN_SHADOW_OFFSET
  48         hex
  49         depends on KASAN
  50         default 0x1C000000000000
  51
  52 config S390
  53         def_bool y
  54         #
  55         # Note: keep this list sorted alphabetically
  56         #
  57         imply IMA_SECURE_AND_OR_TRUSTED_BOOT
  58         select ARCH_32BIT_USTAT_F_TINODE
  59         select ARCH_BINFMT_ELF_STATE
  60         select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM
  61         select ARCH_ENABLE_MEMORY_HOTREMOVE
  62         select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
  63         select ARCH_HAS_DEBUG_VM_PGTABLE
  64         select ARCH_HAS_DEBUG_WX
  65         select ARCH_HAS_DEVMEM_IS_ALLOWED
  66         select ARCH_HAS_ELF_RANDOMIZE
  67         select ARCH_HAS_FORCE_DMA_UNENCRYPTED
  68         select ARCH_HAS_FORTIFY_SOURCE
  69         select ARCH_HAS_GCOV_PROFILE_ALL
  70         select ARCH_HAS_GIGANTIC_PAGE
  71         select ARCH_HAS_KCOV
  72         select ARCH_HAS_MEM_ENCRYPT
  73         select ARCH_HAS_PTE_SPECIAL
  74         select ARCH_HAS_SCALED_CPUTIME
  75         select ARCH_HAS_SET_MEMORY
  76         select ARCH_HAS_STRICT_KERNEL_RWX
  77         select ARCH_HAS_STRICT_MODULE_RWX
  78         select ARCH_HAS_SYSCALL_WRAPPER
  79         select ARCH_HAS_UBSAN_SANITIZE_ALL
  80         select ARCH_HAS_VDSO_DATA
  81         select ARCH_HAVE_NMI_SAFE_CMPXCHG
  82         select ARCH_INLINE_READ_LOCK
  83         select ARCH_INLINE_READ_LOCK_BH
  84         select ARCH_INLINE_READ_LOCK_IRQ
  85         select ARCH_INLINE_READ_LOCK_IRQSAVE
  86         select ARCH_INLINE_READ_TRYLOCK
  87         select ARCH_INLINE_READ_UNLOCK
  88         select ARCH_INLINE_READ_UNLOCK_BH
  89         select ARCH_INLINE_READ_UNLOCK_IRQ
  90         select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
  91         select ARCH_INLINE_SPIN_LOCK
  92         select ARCH_INLINE_SPIN_LOCK_BH
  93         select ARCH_INLINE_SPIN_LOCK_IRQ
  94         select ARCH_INLINE_SPIN_LOCK_IRQSAVE
  95         select ARCH_INLINE_SPIN_TRYLOCK
  96         select ARCH_INLINE_SPIN_TRYLOCK_BH
  97         select ARCH_INLINE_SPIN_UNLOCK
  98         select ARCH_INLINE_SPIN_UNLOCK_BH
  99         select ARCH_INLINE_SPIN_UNLOCK_IRQ
 100         select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
 101         select ARCH_INLINE_WRITE_LOCK
 102         select ARCH_INLINE_WRITE_LOCK_BH
 103         select ARCH_INLINE_WRITE_LOCK_IRQ
 104         select ARCH_INLINE_WRITE_LOCK_IRQSAVE
 105         select ARCH_INLINE_WRITE_TRYLOCK
 106         select ARCH_INLINE_WRITE_UNLOCK
 107         select ARCH_INLINE_WRITE_UNLOCK_BH
 108         select ARCH_INLINE_WRITE_UNLOCK_IRQ
 109         select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 110         select ARCH_STACKWALK
 111         select ARCH_SUPPORTS_ATOMIC_RMW
 112         select ARCH_SUPPORTS_DEBUG_PAGEALLOC
 113         select ARCH_SUPPORTS_HUGETLBFS
 114         select ARCH_SUPPORTS_NUMA_BALANCING
 115         select ARCH_USE_BUILTIN_BSWAP
 116         select ARCH_USE_CMPXCHG_LOCKREF
 117         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 118         select ARCH_WANTS_NO_INSTR
 119         select ARCH_WANT_DEFAULT_BPF_JIT
 120         select ARCH_WANT_IPC_PARSE_VERSION
 121         select BUILDTIME_TABLE_SORT
 122         select CLONE_BACKWARDS2
 123         select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
 124         select DMA_OPS if PCI
 125         select DYNAMIC_FTRACE if FUNCTION_TRACER
 126         select GENERIC_ALLOCATOR
 127         select GENERIC_CPU_AUTOPROBE
 128         select GENERIC_CPU_VULNERABILITIES
 129         select GENERIC_ENTRY
 130         select GENERIC_FIND_FIRST_BIT
 131         select GENERIC_GETTIMEOFDAY
 132         select GENERIC_PTDUMP
 133         select GENERIC_SMP_IDLE_THREAD
 134         select GENERIC_TIME_VSYSCALL
 135         select GENERIC_VDSO_TIME_NS
 136         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
 137         select HAVE_ARCH_AUDITSYSCALL
 138         select HAVE_ARCH_JUMP_LABEL
 139         select HAVE_ARCH_JUMP_LABEL_RELATIVE
 140         select HAVE_ARCH_KASAN
 141         select HAVE_ARCH_KASAN_VMALLOC
 142         select HAVE_ARCH_KCSAN
 143         select HAVE_ARCH_KFENCE
 144         select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
 145         select HAVE_ARCH_SECCOMP_FILTER
 146         select HAVE_ARCH_SOFT_DIRTY
 147         select HAVE_ARCH_TRACEHOOK
 148         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 149         select HAVE_ARCH_VMAP_STACK
 150         select HAVE_ASM_MODVERSIONS
 151         select HAVE_CMPXCHG_DOUBLE
 152         select HAVE_CMPXCHG_LOCAL
 153         select HAVE_DEBUG_KMEMLEAK
 154         select HAVE_DMA_CONTIGUOUS
 155         select HAVE_DYNAMIC_FTRACE
 156         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 157         select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
 158         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 159         select HAVE_FAST_GUP
 160         select HAVE_FENTRY
 161         select HAVE_FTRACE_MCOUNT_RECORD
 162         select HAVE_FUNCTION_ERROR_INJECTION
 163         select HAVE_FUNCTION_GRAPH_TRACER
 164         select HAVE_FUNCTION_TRACER
 165         select HAVE_FUTEX_CMPXCHG if FUTEX
 166         select HAVE_GCC_PLUGINS
 167         select HAVE_GENERIC_VDSO
 168         select HAVE_IOREMAP_PROT if PCI
 169         select HAVE_KERNEL_BZIP2
 170         select HAVE_KERNEL_GZIP
 171         select HAVE_KERNEL_LZ4
 172         select HAVE_KERNEL_LZMA
 173         select HAVE_KERNEL_LZO
 174         select HAVE_KERNEL_UNCOMPRESSED
 175         select HAVE_KERNEL_XZ
 176         select HAVE_KERNEL_ZSTD
 177         select HAVE_KPROBES
 178         select HAVE_KPROBES_ON_FTRACE
 179         select HAVE_KRETPROBES
 180         select HAVE_KVM
 181         select HAVE_LIVEPATCH
 182         select HAVE_MEMBLOCK_PHYS_MAP
 183         select HAVE_MOD_ARCH_SPECIFIC
 184         select HAVE_NMI
 185         select HAVE_NOP_MCOUNT
 186         select HAVE_PCI
 187         select HAVE_PERF_EVENTS
 188         select HAVE_PERF_REGS
 189         select HAVE_PERF_USER_STACK_DUMP
 190         select HAVE_REGS_AND_STACK_ACCESS_API
 191         select HAVE_RELIABLE_STACKTRACE
 192         select HAVE_RSEQ
 193         select HAVE_SOFTIRQ_ON_OWN_STACK
 194         select HAVE_SYSCALL_TRACEPOINTS
 195         select HAVE_VIRT_CPU_ACCOUNTING
 196         select HAVE_VIRT_CPU_ACCOUNTING_IDLE
 197         select IOMMU_HELPER             if PCI
 198         select IOMMU_SUPPORT            if PCI
 199         select MMU_GATHER_NO_GATHER
 200         select MMU_GATHER_RCU_TABLE_FREE
 201         select MODULES_USE_ELF_RELA
 202         select NEED_DMA_MAP_STATE       if PCI
 203         select NEED_SG_DMA_LENGTH       if PCI
 204         select OLD_SIGACTION
 205         select OLD_SIGSUSPEND3
 206         select PCI_DOMAINS              if PCI
 207         select PCI_MSI                  if PCI
 208         select PCI_MSI_ARCH_FALLBACKS   if PCI_MSI
 209         select SPARSE_IRQ
 210         select SWIOTLB
 211         select SYSCTL_EXCEPTION_TRACE
 212         select THREAD_INFO_IN_TASK
 213         select TRACE_IRQFLAGS_SUPPORT
 214         select TTY
 215         select VIRT_CPU_ACCOUNTING
 216         select ZONE_DMA
 217         # Note: keep the above list sorted alphabetically
 218
 219 config SCHED_OMIT_FRAME_POINTER
 220         def_bool y
 221
 222 config PGTABLE_LEVELS
 223         int
 224         default 5
 225
 226 source "kernel/livepatch/Kconfig"
 227
 228 menu "Processor type and features"
 229
 230 config HAVE_MARCH_Z900_FEATURES
 231         def_bool n
 232
 233 config HAVE_MARCH_Z990_FEATURES
 234         def_bool n
 235         select HAVE_MARCH_Z900_FEATURES
 236
 237 config HAVE_MARCH_Z9_109_FEATURES
 238         def_bool n
 239         select HAVE_MARCH_Z990_FEATURES
 240
 241 config HAVE_MARCH_Z10_FEATURES
 242         def_bool n
 243         select HAVE_MARCH_Z9_109_FEATURES
 244
 245 config HAVE_MARCH_Z196_FEATURES
 246         def_bool n
 247         select HAVE_MARCH_Z10_FEATURES
 248
 249 config HAVE_MARCH_ZEC12_FEATURES
 250         def_bool n
 251         select HAVE_MARCH_Z196_FEATURES
 252
 253 config HAVE_MARCH_Z13_FEATURES
 254         def_bool n
 255         select HAVE_MARCH_ZEC12_FEATURES
 256
 257 config HAVE_MARCH_Z14_FEATURES
 258         def_bool n
 259         select HAVE_MARCH_Z13_FEATURES
 260
 261 config HAVE_MARCH_Z15_FEATURES
 262         def_bool n
 263         select HAVE_MARCH_Z14_FEATURES
 264
 265 choice
 266         prompt "Processor type"
 267         default MARCH_Z196
 268
 269 config MARCH_Z900
 270         bool "IBM zSeries model z800 and z900"
 271         select HAVE_MARCH_Z900_FEATURES
 272         depends on $(cc-option,-march=z900)
 273         help
 274           Select this to enable optimizations for model z800/z900 (2064 and
 275           2066 series). This will enable some optimizations that are not
 276           available on older ESA/390 (31 Bit) only CPUs.
 277
 278 config MARCH_Z990
 279         bool "IBM zSeries model z890 and z990"
 280         select HAVE_MARCH_Z990_FEATURES
 281         depends on $(cc-option,-march=z990)
 282         help
 283           Select this to enable optimizations for model z890/z990 (2084 and
 284           2086 series). The kernel will be slightly faster but will not work
 285           on older machines.
 286
 287 config MARCH_Z9_109
 288         bool "IBM System z9"
 289         select HAVE_MARCH_Z9_109_FEATURES
 290         depends on $(cc-option,-march=z9-109)
 291         help
 292           Select this to enable optimizations for IBM System z9 (2094 and
 293           2096 series). The kernel will be slightly faster but will not work
 294           on older machines.
 295
 296 config MARCH_Z10
 297         bool "IBM System z10"
 298         select HAVE_MARCH_Z10_FEATURES
 299         depends on $(cc-option,-march=z10)
 300         help
 301           Select this to enable optimizations for IBM System z10 (2097 and
 302           2098 series). The kernel will be slightly faster but will not work
 303           on older machines.
 304
 305 config MARCH_Z196
 306         bool "IBM zEnterprise 114 and 196"
 307         select HAVE_MARCH_Z196_FEATURES
 308         depends on $(cc-option,-march=z196)
 309         help
 310           Select this to enable optimizations for IBM zEnterprise 114 and 196
 311           (2818 and 2817 series). The kernel will be slightly faster but will
 312           not work on older machines.
 313
 314 config MARCH_ZEC12
 315         bool "IBM zBC12 and zEC12"
 316         select HAVE_MARCH_ZEC12_FEATURES
 317         depends on $(cc-option,-march=zEC12)
 318         help
 319           Select this to enable optimizations for IBM zBC12 and zEC12 (2828 and
 320           2827 series). The kernel will be slightly faster but will not work on
 321           older machines.
 322
 323 config MARCH_Z13
 324         bool "IBM z13s and z13"
 325         select HAVE_MARCH_Z13_FEATURES
 326         depends on $(cc-option,-march=z13)
 327         help
 328           Select this to enable optimizations for IBM z13s and z13 (2965 and
 329           2964 series). The kernel will be slightly faster but will not work on
 330           older machines.
 331
 332 config MARCH_Z14
 333         bool "IBM z14 ZR1 and z14"
 334         select HAVE_MARCH_Z14_FEATURES
 335         depends on $(cc-option,-march=z14)
 336         help
 337           Select this to enable optimizations for IBM z14 ZR1 and z14 (3907
 338           and 3906 series). The kernel will be slightly faster but will not
 339           work on older machines.
 340
 341 config MARCH_Z15
 342         bool "IBM z15"
 343         select HAVE_MARCH_Z15_FEATURES
 344         depends on $(cc-option,-march=z15)
 345         help
 346           Select this to enable optimizations for IBM z15 (8562
 347           and 8561 series). The kernel will be slightly faster but will not
 348           work on older machines.
 349
 350 endchoice
 351
 352 config MARCH_Z900_TUNE
 353         def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT
 354
 355 config MARCH_Z990_TUNE
 356         def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT
 357
 358 config MARCH_Z9_109_TUNE
 359         def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT
 360
 361 config MARCH_Z10_TUNE
 362         def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT
 363
 364 config MARCH_Z196_TUNE
 365         def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT
 366
 367 config MARCH_ZEC12_TUNE
 368         def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT
 369
 370 config MARCH_Z13_TUNE
 371         def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT
 372
 373 config MARCH_Z14_TUNE
 374         def_bool TUNE_Z14 || MARCH_Z14 && TUNE_DEFAULT
 375
 376 config MARCH_Z15_TUNE
 377         def_bool TUNE_Z15 || MARCH_Z15 && TUNE_DEFAULT
 378
 379 choice
 380         prompt "Tune code generation"
 381         default TUNE_DEFAULT
 382         help
 383           Cause the compiler to tune (-mtune) the generated code for a machine.
 384           This will make the code run faster on the selected machine but
 385           somewhat slower on other machines.
 386           This option only changes how the compiler emits instructions, not the
 387           selection of instructions itself, so the resulting kernel will run on
 388           all other machines.
 389
 390 config TUNE_DEFAULT
 391         bool "Default"
 392         help
 393           Tune the generated code for the target processor for which the kernel
 394           will be compiled.
 395
 396 config TUNE_Z900
 397         bool "IBM zSeries model z800 and z900"
 398         depends on $(cc-option,-mtune=z900)
 399
 400 config TUNE_Z990
 401         bool "IBM zSeries model z890 and z990"
 402         depends on $(cc-option,-mtune=z990)
 403
 404 config TUNE_Z9_109
 405         bool "IBM System z9"
 406         depends on $(cc-option,-mtune=z9-109)
 407
 408 config TUNE_Z10
 409         bool "IBM System z10"
 410         depends on $(cc-option,-mtune=z10)
 411
 412 config TUNE_Z196
 413         bool "IBM zEnterprise 114 and 196"
 414         depends on $(cc-option,-mtune=z196)
 415
 416 config TUNE_ZEC12
 417         bool "IBM zBC12 and zEC12"
 418         depends on $(cc-option,-mtune=zEC12)
 419
 420 config TUNE_Z13
 421         bool "IBM z13s and z13"
 422         depends on $(cc-option,-mtune=z13)
 423
 424 config TUNE_Z14
 425         bool "IBM z14 ZR1 and z14"
 426         depends on $(cc-option,-mtune=z14)
 427
 428 config TUNE_Z15
 429         bool "IBM z15"
 430         depends on $(cc-option,-mtune=z15)
 431
 432 endchoice
 433
 434 config 64BIT
 435         def_bool y
 436
 437 config COMPAT
 438         def_bool y
 439         prompt "Kernel support for 31 bit emulation"
 440         select ARCH_WANT_OLD_COMPAT_IPC
 441         select COMPAT_OLD_SIGACTION
 442         select HAVE_UID16
 443         depends on MULTIUSER
 444         depends on !CC_IS_CLANG
 445         help
 446           Select this option if you want to enable your system kernel to
 447           handle system-calls from ELF binaries for 31 bit ESA.  This option
 448           (and some other stuff like libraries and such) is needed for
 449           executing 31 bit applications.  It is safe to say "Y".
 450
 451 config SYSVIPC_COMPAT
 452         def_bool y if COMPAT && SYSVIPC
 453
 454 config SMP
 455         def_bool y
 456
 457 config NR_CPUS
 458         int "Maximum number of CPUs (2-512)"
 459         range 2 512
 460         default "64"
 461         help
 462           This allows you to specify the maximum number of CPUs which this
 463           kernel will support. The maximum supported value is 512 and the
 464           minimum value which makes sense is 2.
 465
 466           This is purely to save memory - each supported CPU adds
 467           approximately sixteen kilobytes to the kernel image.
 468
 469 config HOTPLUG_CPU
 470         def_bool y
 471
 472 config NUMA
 473         bool "NUMA support"
 474         depends on SCHED_TOPOLOGY
 475         default n
 476         help
 477           Enable NUMA support
 478
 479           This option adds NUMA support to the kernel.
 480
 481 config NODES_SHIFT
 482         int
 483         depends on NUMA
 484         default "1"
 485
 486 config SCHED_SMT
 487         def_bool n
 488
 489 config SCHED_MC
 490         def_bool n
 491
 492 config SCHED_BOOK
 493         def_bool n
 494
 495 config SCHED_DRAWER
 496         def_bool n
 497
 498 config SCHED_TOPOLOGY
 499         def_bool y
 500         prompt "Topology scheduler support"
 501         select SCHED_SMT
 502         select SCHED_MC
 503         select SCHED_BOOK
 504         select SCHED_DRAWER
 505         help
 506           Topology scheduler support improves the CPU scheduler's decision
 507           making when dealing with machines that have multi-threading,
 508           multiple cores or multiple books.
 509
 510 source "kernel/Kconfig.hz"
 511
 512 config KEXEC
 513         def_bool y
 514         select KEXEC_CORE
 515
 516 config KEXEC_FILE
 517         bool "kexec file based system call"
 518         select KEXEC_CORE
 519         select BUILD_BIN2C
 520         depends on CRYPTO
 521         depends on CRYPTO_SHA256
 522         depends on CRYPTO_SHA256_S390
 523         help
 524           Enable the kexec file based system call. In contrast to the normal
 525           kexec system call this system call takes file descriptors for the
 526           kernel and initramfs as arguments.
 527
 528 config ARCH_HAS_KEXEC_PURGATORY
 529         def_bool y
 530         depends on KEXEC_FILE
 531
 532 config KEXEC_SIG
 533         bool "Verify kernel signature during kexec_file_load() syscall"
 534         depends on KEXEC_FILE && MODULE_SIG_FORMAT
 535         help
 536           This option makes kernel signature verification mandatory for
 537           the kexec_file_load() syscall.
 538
 539           In addition to that option, you need to enable signature
 540           verification for the corresponding kernel image type being
 541           loaded in order for this to work.
 542
 543 config ARCH_RANDOM
 544         def_bool y
 545         prompt "s390 architectural random number generation API"
 546         help
 547           Enable the s390 architectural random number generation API
 548           to provide random data for all consumers within the Linux
 549           kernel.
 550
 551           When enabled the arch_random_* functions declared in linux/random.h
 552           are implemented. The implementation is based on the s390 CPACF
 553           instruction subfunction TRNG which provides a real true random
 554           number generator.
 555
 556           If unsure, say Y.
 557
 558 config KERNEL_NOBP
 559         def_bool n
 560         prompt "Enable modified branch prediction for the kernel by default"
 561         help
 562           If this option is selected the kernel will switch to a modified
 563           branch prediction mode if the firmware interface is available.
 564           The modified branch prediction mode improves the behaviour in
 565           regard to speculative execution.
 566
 567           With the option enabled the kernel parameter "nobp=0" or "nospec"
 568           can be used to run the kernel in the normal branch prediction mode.
 569
 570           With the option disabled the modified branch prediction mode is
 571           enabled with the "nobp=1" kernel parameter.
 572
 573           If unsure, say N.
 574
 575 config EXPOLINE
 576         def_bool n
 577         prompt "Avoid speculative indirect branches in the kernel"
 578         help
 579           Compile the kernel with the expoline compiler options to guard
 580           against kernel-to-user data leaks by avoiding speculative indirect
 581           branches.
 582           Requires a compiler with -mindirect-branch=thunk support for full
 583           protection. The kernel may run slower.
 584
 585           If unsure, say N.
 586
 587 choice
 588         prompt "Expoline default"
 589         depends on EXPOLINE
 590         default EXPOLINE_FULL
 591
 592 config EXPOLINE_OFF
 593         bool "spectre_v2=off"
 594
 595 config EXPOLINE_AUTO
 596         bool "spectre_v2=auto"
 597
 598 config EXPOLINE_FULL
 599         bool "spectre_v2=on"
 600
 601 endchoice
 602
 603 config RELOCATABLE
 604         bool "Build a relocatable kernel"
 605         select MODULE_REL_CRCS if MODVERSIONS
 606         default y
 607         help
 608           This builds a kernel image that retains relocation information
 609           so it can be loaded at an arbitrary address.
 610           The kernel is linked as a position-independent executable (PIE)
 611           and contains dynamic relocations which are processed early in the
 612           bootup process.
 613           The relocations make the kernel image about 15% larger (compressed
 614           10%), but are discarded at runtime.
 615
 616 config RANDOMIZE_BASE
 617         bool "Randomize the address of the kernel image (KASLR)"
 618         depends on RELOCATABLE
 619         default y
 620         help
 621           In support of Kernel Address Space Layout Randomization (KASLR),
 622           this randomizes the address at which the kernel image is loaded,
 623           as a security feature that deters exploit attempts relying on
 624           knowledge of the location of kernel internals.
 625
 626 endmenu
 627
 628 menu "Memory setup"
 629
 630 config ARCH_SPARSEMEM_ENABLE
 631         def_bool y
 632         select SPARSEMEM_VMEMMAP_ENABLE
 633         select SPARSEMEM_VMEMMAP
 634
 635 config ARCH_SPARSEMEM_DEFAULT
 636         def_bool y
 637
 638 config MAX_PHYSMEM_BITS
 639         int "Maximum size of supported physical memory in bits (42-53)"
 640         range 42 53
 641         default "46"
 642         help
 643           This option specifies the maximum supported size of physical memory
 644           in bits. Supported is any size between 2^42 (4TB) and 2^53 (8PB).
 645           Increasing the number of bits also increases the kernel image size.
 646           By default 46 bits (64TB) are supported.
 647
 648 config PACK_STACK
 649         def_bool y
 650         prompt "Pack kernel stack"
 651         help
 652           This option enables the compiler option -mkernel-backchain if it
 653           is available. If the option is available the compiler supports
 654           the new stack layout which dramatically reduces the minimum stack
 655           frame size. With an old compiler a non-leaf function needs a
 656           minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
 657           -mkernel-backchain the minimum size drops to 16 byte on 31 bit
 658           and 24 byte on 64 bit.
 659
 660           Say Y if you are unsure.
 661
 662 config CHECK_STACK
 663         def_bool y
 664         depends on !VMAP_STACK
 665         prompt "Detect kernel stack overflow"
 666         help
 667           This option enables the compiler option -mstack-guard and
 668           -mstack-size if they are available. If the compiler supports them
 669           it will emit additional code to each function prolog to trigger
 670           an illegal operation if the kernel stack is about to overflow.
 671
 672           Say N if you are unsure.
 673
 674 config STACK_GUARD
 675         int "Size of the guard area (128-1024)"
 676         range 128 1024
 677         depends on CHECK_STACK
 678         default "256"
 679         help
 680           This allows you to specify the size of the guard area at the lower
 681           end of the kernel stack. If the kernel stack points into the guard
 682           area on function entry an illegal operation is triggered. The size
 683           needs to be a power of 2. Please keep in mind that the size of an
 684           interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
 685           The minimum size for the stack guard should be 256 for 31 bit and
 686           512 for 64 bit.
 687
 688 endmenu
 689
 690 menu "I/O subsystem"
 691
 692 config QDIO
 693         def_tristate y
 694         prompt "QDIO support"
 695         help
 696           This driver provides the Queued Direct I/O base support for
 697           IBM System z.
 698
 699           To compile this driver as a module, choose M here: the
 700           module will be called qdio.
 701
 702           If unsure, say Y.
 703
 704 if PCI
 705
 706 config PCI_NR_FUNCTIONS
 707         int "Maximum number of PCI functions (1-4096)"
 708         range 1 4096
 709         default "512"
 710         help
 711           This allows you to specify the maximum number of PCI functions which
 712           this kernel will support.
 713
 714 endif # PCI
 715
 716 config HAS_IOMEM
 717         def_bool PCI
 718
 719 config CHSC_SCH
 720         def_tristate m
 721         prompt "Support for CHSC subchannels"
 722         help
 723           This driver allows usage of CHSC subchannels. A CHSC subchannel
 724           is usually present on LPAR only.
 725           The driver creates a device /dev/chsc, which may be used to
 726           obtain I/O configuration information about the machine and
 727           to issue asynchronous chsc commands (DANGEROUS).
 728           You will usually only want to use this interface on a special
 729           LPAR designated for system management.
 730
 731           To compile this driver as a module, choose M here: the
 732           module will be called chsc_sch.
 733
 734           If unsure, say N.
 735
 736 config SCM_BUS
 737         def_bool y
 738         prompt "SCM bus driver"
 739         help
 740           Bus driver for Storage Class Memory.
 741
 742 config EADM_SCH
 743         def_tristate m
 744         prompt "Support for EADM subchannels"
 745         depends on SCM_BUS
 746         help
 747           This driver allows usage of EADM subchannels. EADM subchannels act
 748           as a communication vehicle for SCM increments.
 749
 750           To compile this driver as a module, choose M here: the
 751           module will be called eadm_sch.
 752
 753 config VFIO_CCW
 754         def_tristate n
 755         prompt "Support for VFIO-CCW subchannels"
 756         depends on S390_CCW_IOMMU && VFIO_MDEV
 757         help
 758           This driver allows usage of I/O subchannels via VFIO-CCW.
 759
 760           To compile this driver as a module, choose M here: the
 761           module will be called vfio_ccw.
 762
 763 config VFIO_AP
 764         def_tristate n
 765         prompt "VFIO support for AP devices"
 766         depends on S390_AP_IOMMU && VFIO_MDEV && KVM
 767         depends on ZCRYPT
 768         help
 769                 This driver grants access to Adjunct Processor (AP) devices
 770                 via the VFIO mediated device interface.
 771
 772                 To compile this driver as a module, choose M here: the module
 773                 will be called vfio_ap.
 774
 775 endmenu
 776
 777 menu "Dump support"
 778
 779 config CRASH_DUMP
 780         bool "kernel crash dumps"
 781         select KEXEC
 782         help
 783           Generate crash dump after being started by kexec.
 784           Crash dump kernels are loaded in the main kernel with kexec-tools
 785           into a specially reserved region and then later executed after
 786           a crash by kdump/kexec.
 787           Refer to <file:Documentation/s390/zfcpdump.rst> for more details on this.
 788           This option also enables s390 zfcpdump.
 789           See also <file:Documentation/s390/zfcpdump.rst>
 790
 791 endmenu
 792
 793 config CCW
 794         def_bool y
 795
 796 config HAVE_PNETID
 797         tristate
 798         default (SMC || CCWGROUP)
 799
 800 menu "Virtualization"
 801
 802 config PROTECTED_VIRTUALIZATION_GUEST
 803         def_bool n
 804         prompt "Protected virtualization guest support"
 805         select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
 806         help
 807           Select this option, if you want to be able to run this
 808           kernel as a protected virtualization KVM guest.
 809           Protected virtualization capable machines have a mini hypervisor
 810           located at machine level (an ultravisor). With help of the
 811           Ultravisor, KVM will be able to run "protected" VMs, special
 812           VMs whose memory and management data are unavailable to KVM.
 813
 814 config PFAULT
 815         def_bool y
 816         prompt "Pseudo page fault support"
 817         help
 818           Select this option, if you want to use PFAULT pseudo page fault
 819           handling under VM. If running native or in LPAR, this option
 820           has no effect. If your VM does not support PFAULT, PAGEEX
 821           pseudo page fault handling will be used.
 822           Note that VM 4.2 supports PFAULT but has a bug in its
 823           implementation that causes some problems.
 824           Everybody who wants to run Linux under VM != VM4.2 should select
 825           this option.
 826
 827 config CMM
 828         def_tristate n
 829         prompt "Cooperative memory management"
 830         help
 831           Select this option, if you want to enable the kernel interface
 832           to reduce the memory size of the system. This is accomplished
 833           by allocating pages of memory and put them "on hold". This only
 834           makes sense for a system running under VM where the unused pages
 835           will be reused by VM for other guest systems. The interface
 836           allows an external monitor to balance memory of many systems.
 837           Everybody who wants to run Linux under VM should select this
 838           option.
 839
 840 config CMM_IUCV
 841         def_bool y
 842         prompt "IUCV special message interface to cooperative memory management"
 843         depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
 844         help
 845           Select this option to enable the special message interface to
 846           the cooperative memory management.
 847
 848 config APPLDATA_BASE
 849         def_bool n
 850         prompt "Linux - VM Monitor Stream, base infrastructure"
 851         depends on PROC_SYSCTL
 852         help
 853           This provides a kernel interface for creating and updating z/VM APPLDATA
 854           monitor records. The monitor records are updated at certain time
 855           intervals, once the timer is started.
 856           Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
 857           i.e. enables or disables monitoring on the Linux side.
 858           A custom interval value (in seconds) can be written to
 859           /proc/appldata/interval.
 860
 861           Defaults are 60 seconds interval and timer off.
 862           The /proc entries can also be read from, showing the current settings.
 863
 864 config APPLDATA_MEM
 865         def_tristate m
 866         prompt "Monitor memory management statistics"
 867         depends on APPLDATA_BASE && VM_EVENT_COUNTERS
 868         help
 869           This provides memory management related data to the Linux - VM Monitor
 870           Stream, like paging/swapping rate, memory utilisation, etc.
 871           Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
 872           APPLDATA monitor record, i.e. enables or disables monitoring this record
 873           on the z/VM side.
 874
 875           Default is disabled.
 876           The /proc entry can also be read from, showing the current settings.
 877
 878           This can also be compiled as a module, which will be called
 879           appldata_mem.o.
 880
 881 config APPLDATA_OS
 882         def_tristate m
 883         prompt "Monitor OS statistics"
 884         depends on APPLDATA_BASE
 885         help
 886           This provides OS related data to the Linux - VM Monitor Stream, like
 887           CPU utilisation, etc.
 888           Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
 889           APPLDATA monitor record, i.e. enables or disables monitoring this record
 890           on the z/VM side.
 891
 892           Default is disabled.
 893           This can also be compiled as a module, which will be called
 894           appldata_os.o.
 895
 896 config APPLDATA_NET_SUM
 897         def_tristate m
 898         prompt "Monitor overall network statistics"
 899         depends on APPLDATA_BASE && NET
 900         help
 901           This provides network related data to the Linux - VM Monitor Stream,
 902           currently there is only a total sum of network I/O statistics, no
 903           per-interface data.
 904           Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
 905           APPLDATA monitor record, i.e. enables or disables monitoring this record
 906           on the z/VM side.
 907
 908           Default is disabled.
 909           This can also be compiled as a module, which will be called
 910           appldata_net_sum.o.
 911
 912 config S390_HYPFS_FS
 913         def_bool y
 914         prompt "s390 hypervisor file system support"
 915         select SYS_HYPERVISOR
 916         help
 917           This is a virtual file system intended to provide accounting
 918           information in an s390 hypervisor environment.
 919
 920 source "arch/s390/kvm/Kconfig"
 921
 922 config S390_GUEST
 923         def_bool y
 924         prompt "s390 support for virtio devices"
 925         select TTY
 926         select VIRTUALIZATION
 927         select VIRTIO
 928         help
 929           Enabling this option adds support for virtio based paravirtual device
 930           drivers on s390.
 931
 932           Select this option if you want to run the kernel as a guest under
 933           the KVM hypervisor.
 934
 935 endmenu
 936
 937 menu "Selftests"
 938
 939 config S390_UNWIND_SELFTEST
 940         def_tristate n
 941         prompt "Test unwind functions"
 942         help
 943           This option enables s390 specific stack unwinder testing kernel
 944           module. This option is not useful for distributions or general
 945           kernels, but only for kernel developers working on architecture code.
 946
 947           Say N if you are unsure.
 948
 949 endmenu