arch/s390/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0
   2 config MMU
   3         def_bool y
   4
   5 config ZONE_DMA
   6         def_bool y
   7
   8 config CPU_BIG_ENDIAN
   9         def_bool y
  10
  11 config LOCKDEP_SUPPORT
  12         def_bool y
  13
  14 config STACKTRACE_SUPPORT
  15         def_bool y
  16
  17 config ARCH_HAS_ILOG2_U32
  18         def_bool n
  19
  20 config ARCH_HAS_ILOG2_U64
  21         def_bool n
  22
  23 config GENERIC_HWEIGHT
  24         def_bool y
  25
  26 config GENERIC_BUG
  27         def_bool y if BUG
  28
  29 config GENERIC_BUG_RELATIVE_POINTERS
  30         def_bool y
  31
  32 config GENERIC_LOCKBREAK
  33         def_bool y if SMP && PREEMPT
  34
  35 config PGSTE
  36         def_bool y if KVM
  37
  38 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
  39         def_bool y
  40
  41 config AUDIT_ARCH
  42         def_bool y
  43
  44 config NO_IOPORT_MAP
  45         def_bool y
  46
  47 config PCI_QUIRKS
  48         def_bool n
  49
  50 config ARCH_SUPPORTS_UPROBES
  51         def_bool y
  52
  53 config KASAN_SHADOW_OFFSET
  54         hex
  55         depends on KASAN
  56         default 0x18000000000000 if KASAN_S390_4_LEVEL_PAGING
  57         default 0x30000000000
  58
  59 config S390
  60         def_bool y
  61         select ARCH_BINFMT_ELF_STATE
  62         select ARCH_HAS_DEVMEM_IS_ALLOWED
  63         select ARCH_HAS_ELF_RANDOMIZE
  64         select ARCH_HAS_FORTIFY_SOURCE
  65         select ARCH_HAS_GCOV_PROFILE_ALL
  66         select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
  67         select ARCH_HAS_KCOV
  68         select ARCH_HAS_PTE_SPECIAL
  69         select ARCH_HAS_SET_MEMORY
  70         select ARCH_HAS_STRICT_KERNEL_RWX
  71         select ARCH_HAS_STRICT_MODULE_RWX
  72         select ARCH_HAS_SYSCALL_WRAPPER
  73         select ARCH_HAS_UBSAN_SANITIZE_ALL
  74         select ARCH_HAVE_NMI_SAFE_CMPXCHG
  75         select ARCH_INLINE_READ_LOCK
  76         select ARCH_INLINE_READ_LOCK_BH
  77         select ARCH_INLINE_READ_LOCK_IRQ
  78         select ARCH_INLINE_READ_LOCK_IRQSAVE
  79         select ARCH_INLINE_READ_TRYLOCK
  80         select ARCH_INLINE_READ_UNLOCK
  81         select ARCH_INLINE_READ_UNLOCK_BH
  82         select ARCH_INLINE_READ_UNLOCK_IRQ
  83         select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
  84         select ARCH_INLINE_SPIN_LOCK
  85         select ARCH_INLINE_SPIN_LOCK_BH
  86         select ARCH_INLINE_SPIN_LOCK_IRQ
  87         select ARCH_INLINE_SPIN_LOCK_IRQSAVE
  88         select ARCH_INLINE_SPIN_TRYLOCK
  89         select ARCH_INLINE_SPIN_TRYLOCK_BH
  90         select ARCH_INLINE_SPIN_UNLOCK
  91         select ARCH_INLINE_SPIN_UNLOCK_BH
  92         select ARCH_INLINE_SPIN_UNLOCK_IRQ
  93         select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
  94         select ARCH_INLINE_WRITE_LOCK
  95         select ARCH_INLINE_WRITE_LOCK_BH
  96         select ARCH_INLINE_WRITE_LOCK_IRQ
  97         select ARCH_INLINE_WRITE_LOCK_IRQSAVE
  98         select ARCH_INLINE_WRITE_TRYLOCK
  99         select ARCH_INLINE_WRITE_UNLOCK
 100         select ARCH_INLINE_WRITE_UNLOCK_BH
 101         select ARCH_INLINE_WRITE_UNLOCK_IRQ
 102         select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 103         select ARCH_SAVE_PAGE_KEYS if HIBERNATION
 104         select ARCH_SUPPORTS_ATOMIC_RMW
 105         select ARCH_SUPPORTS_NUMA_BALANCING
 106         select ARCH_USE_BUILTIN_BSWAP
 107         select ARCH_USE_CMPXCHG_LOCKREF
 108         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 109         select ARCH_WANT_IPC_PARSE_VERSION
 110         select BUILDTIME_EXTABLE_SORT
 111         select CLONE_BACKWARDS2
 112         select DYNAMIC_FTRACE if FUNCTION_TRACER
 113         select GENERIC_CLOCKEVENTS
 114         select GENERIC_CPU_AUTOPROBE
 115         select GENERIC_CPU_DEVICES if !SMP
 116         select GENERIC_CPU_VULNERABILITIES
 117         select GENERIC_FIND_FIRST_BIT
 118         select GENERIC_SMP_IDLE_THREAD
 119         select GENERIC_TIME_VSYSCALL
 120         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
 121         select HAVE_ARCH_AUDITSYSCALL
 122         select HAVE_ARCH_JUMP_LABEL
 123         select HAVE_ARCH_JUMP_LABEL_RELATIVE
 124         select HAVE_ARCH_KASAN
 125         select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
 126         select HAVE_ARCH_SECCOMP_FILTER
 127         select HAVE_ARCH_SOFT_DIRTY
 128         select HAVE_ARCH_TRACEHOOK
 129         select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 130         select HAVE_ARCH_VMAP_STACK
 131         select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
 132         select HAVE_CMPXCHG_DOUBLE
 133         select HAVE_CMPXCHG_LOCAL
 134         select HAVE_COPY_THREAD_TLS
 135         select HAVE_DEBUG_KMEMLEAK
 136         select HAVE_DMA_CONTIGUOUS
 137         select HAVE_DYNAMIC_FTRACE
 138         select HAVE_DYNAMIC_FTRACE_WITH_REGS
 139         select HAVE_EFFICIENT_UNALIGNED_ACCESS
 140         select HAVE_FENTRY
 141         select HAVE_FTRACE_MCOUNT_RECORD
 142         select HAVE_FUNCTION_GRAPH_TRACER
 143         select HAVE_FUNCTION_TRACER
 144         select HAVE_FUTEX_CMPXCHG if FUTEX
 145         select HAVE_GCC_PLUGINS
 146         select HAVE_GENERIC_GUP
 147         select HAVE_KERNEL_BZIP2
 148         select HAVE_KERNEL_GZIP
 149         select HAVE_KERNEL_LZ4
 150         select HAVE_KERNEL_LZMA
 151         select HAVE_KERNEL_LZO
 152         select HAVE_KERNEL_UNCOMPRESSED
 153         select HAVE_KERNEL_XZ
 154         select HAVE_KPROBES
 155         select HAVE_KRETPROBES
 156         select HAVE_KVM
 157         select HAVE_LIVEPATCH
 158         select HAVE_PERF_REGS
 159         select HAVE_PERF_USER_STACK_DUMP
 160         select HAVE_MEMBLOCK_NODE_MAP
 161         select HAVE_MEMBLOCK_PHYS_MAP
 162         select HAVE_MMU_GATHER_NO_GATHER
 163         select HAVE_MOD_ARCH_SPECIFIC
 164         select HAVE_NOP_MCOUNT
 165         select HAVE_OPROFILE
 166         select HAVE_PCI
 167         select HAVE_PERF_EVENTS
 168         select HAVE_RCU_TABLE_FREE
 169         select HAVE_REGS_AND_STACK_ACCESS_API
 170         select HAVE_RSEQ
 171         select HAVE_SYSCALL_TRACEPOINTS
 172         select HAVE_VIRT_CPU_ACCOUNTING
 173         select IOMMU_HELPER             if PCI
 174         select IOMMU_SUPPORT            if PCI
 175         select MODULES_USE_ELF_RELA
 176         select NEED_DMA_MAP_STATE       if PCI
 177         select NEED_SG_DMA_LENGTH       if PCI
 178         select OLD_SIGACTION
 179         select OLD_SIGSUSPEND3
 180         select PCI_DOMAINS              if PCI
 181         select PCI_MSI                  if PCI
 182         select SPARSE_IRQ
 183         select SYSCTL_EXCEPTION_TRACE
 184         select THREAD_INFO_IN_TASK
 185         select TTY
 186         select VIRT_CPU_ACCOUNTING
 187         select ARCH_HAS_SCALED_CPUTIME
 188         select HAVE_NMI
 189
 190
 191 config SCHED_OMIT_FRAME_POINTER
 192         def_bool y
 193
 194 config PGTABLE_LEVELS
 195         int
 196         default 5
 197
 198 source "kernel/livepatch/Kconfig"
 199
 200 menu "Processor type and features"
 201
 202 config HAVE_MARCH_Z900_FEATURES
 203         def_bool n
 204
 205 config HAVE_MARCH_Z990_FEATURES
 206         def_bool n
 207         select HAVE_MARCH_Z900_FEATURES
 208
 209 config HAVE_MARCH_Z9_109_FEATURES
 210         def_bool n
 211         select HAVE_MARCH_Z990_FEATURES
 212
 213 config HAVE_MARCH_Z10_FEATURES
 214         def_bool n
 215         select HAVE_MARCH_Z9_109_FEATURES
 216
 217 config HAVE_MARCH_Z196_FEATURES
 218         def_bool n
 219         select HAVE_MARCH_Z10_FEATURES
 220
 221 config HAVE_MARCH_ZEC12_FEATURES
 222         def_bool n
 223         select HAVE_MARCH_Z196_FEATURES
 224
 225 config HAVE_MARCH_Z13_FEATURES
 226         def_bool n
 227         select HAVE_MARCH_ZEC12_FEATURES
 228
 229 config HAVE_MARCH_Z14_FEATURES
 230         def_bool n
 231         select HAVE_MARCH_Z13_FEATURES
 232
 233 choice
 234         prompt "Processor type"
 235         default MARCH_Z196
 236
 237 config MARCH_Z900
 238         bool "IBM zSeries model z800 and z900"
 239         depends on !CC_IS_CLANG
 240         select HAVE_MARCH_Z900_FEATURES
 241         help
 242           Select this to enable optimizations for model z800/z900 (2064 and
 243           2066 series). This will enable some optimizations that are not
 244           available on older ESA/390 (31 Bit) only CPUs.
 245
 246 config MARCH_Z990
 247         bool "IBM zSeries model z890 and z990"
 248         depends on !CC_IS_CLANG
 249         select HAVE_MARCH_Z990_FEATURES
 250         help
 251           Select this to enable optimizations for model z890/z990 (2084 and
 252           2086 series). The kernel will be slightly faster but will not work
 253           on older machines.
 254
 255 config MARCH_Z9_109
 256         bool "IBM System z9"
 257         depends on !CC_IS_CLANG
 258         select HAVE_MARCH_Z9_109_FEATURES
 259         help
 260           Select this to enable optimizations for IBM System z9 (2094 and
 261           2096 series). The kernel will be slightly faster but will not work
 262           on older machines.
 263
 264 config MARCH_Z10
 265         bool "IBM System z10"
 266         select HAVE_MARCH_Z10_FEATURES
 267         help
 268           Select this to enable optimizations for IBM System z10 (2097 and
 269           2098 series). The kernel will be slightly faster but will not work
 270           on older machines.
 271
 272 config MARCH_Z196
 273         bool "IBM zEnterprise 114 and 196"
 274         select HAVE_MARCH_Z196_FEATURES
 275         help
 276           Select this to enable optimizations for IBM zEnterprise 114 and 196
 277           (2818 and 2817 series). The kernel will be slightly faster but will
 278           not work on older machines.
 279
 280 config MARCH_ZEC12
 281         bool "IBM zBC12 and zEC12"
 282         select HAVE_MARCH_ZEC12_FEATURES
 283         help
 284           Select this to enable optimizations for IBM zBC12 and zEC12 (2828 and
 285           2827 series). The kernel will be slightly faster but will not work on
 286           older machines.
 287
 288 config MARCH_Z13
 289         bool "IBM z13s and z13"
 290         select HAVE_MARCH_Z13_FEATURES
 291         help
 292           Select this to enable optimizations for IBM z13s and z13 (2965 and
 293           2964 series). The kernel will be slightly faster but will not work on
 294           older machines.
 295
 296 config MARCH_Z14
 297         bool "IBM z14 ZR1 and z14"
 298         select HAVE_MARCH_Z14_FEATURES
 299         help
 300           Select this to enable optimizations for IBM z14 ZR1 and z14 (3907
 301           and 3906 series). The kernel will be slightly faster but will not
 302           work on older machines.
 303
 304 endchoice
 305
 306 config MARCH_Z900_TUNE
 307         def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT
 308
 309 config MARCH_Z990_TUNE
 310         def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT
 311
 312 config MARCH_Z9_109_TUNE
 313         def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT
 314
 315 config MARCH_Z10_TUNE
 316         def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT
 317
 318 config MARCH_Z196_TUNE
 319         def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT
 320
 321 config MARCH_ZEC12_TUNE
 322         def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT
 323
 324 config MARCH_Z13_TUNE
 325         def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT
 326
 327 config MARCH_Z14_TUNE
 328         def_bool TUNE_Z14 || MARCH_Z14 && TUNE_DEFAULT
 329
 330 choice
 331         prompt "Tune code generation"
 332         default TUNE_DEFAULT
 333         help
 334           Cause the compiler to tune (-mtune) the generated code for a machine.
 335           This will make the code run faster on the selected machine but
 336           somewhat slower on other machines.
 337           This option only changes how the compiler emits instructions, not the
 338           selection of instructions itself, so the resulting kernel will run on
 339           all other machines.
 340
 341 config TUNE_DEFAULT
 342         bool "Default"
 343         help
 344           Tune the generated code for the target processor for which the kernel
 345           will be compiled.
 346
 347 config TUNE_Z900
 348         bool "IBM zSeries model z800 and z900"
 349         depends on !CC_IS_CLANG
 350
 351 config TUNE_Z990
 352         bool "IBM zSeries model z890 and z990"
 353         depends on !CC_IS_CLANG
 354
 355 config TUNE_Z9_109
 356         bool "IBM System z9"
 357         depends on !CC_IS_CLANG
 358
 359 config TUNE_Z10
 360         bool "IBM System z10"
 361
 362 config TUNE_Z196
 363         bool "IBM zEnterprise 114 and 196"
 364
 365 config TUNE_ZEC12
 366         bool "IBM zBC12 and zEC12"
 367
 368 config TUNE_Z13
 369         bool "IBM z13"
 370
 371 config TUNE_Z14
 372         bool "IBM z14"
 373
 374 endchoice
 375
 376 config 64BIT
 377         def_bool y
 378
 379 config COMPAT
 380         def_bool y
 381         prompt "Kernel support for 31 bit emulation"
 382         select COMPAT_BINFMT_ELF if BINFMT_ELF
 383         select ARCH_WANT_OLD_COMPAT_IPC
 384         select COMPAT_OLD_SIGACTION
 385         select HAVE_UID16
 386         depends on MULTIUSER
 387         help
 388           Select this option if you want to enable your system kernel to
 389           handle system-calls from ELF binaries for 31 bit ESA.  This option
 390           (and some other stuff like libraries and such) is needed for
 391           executing 31 bit applications.  It is safe to say "Y".
 392
 393 config COMPAT_VDSO
 394         def_bool COMPAT && !CC_IS_CLANG
 395
 396 config SYSVIPC_COMPAT
 397         def_bool y if COMPAT && SYSVIPC
 398
 399 config SMP
 400         def_bool y
 401         prompt "Symmetric multi-processing support"
 402         ---help---
 403           This enables support for systems with more than one CPU. If you have
 404           a system with only one CPU, like most personal computers, say N. If
 405           you have a system with more than one CPU, say Y.
 406
 407           If you say N here, the kernel will run on uni- and multiprocessor
 408           machines, but will use only one CPU of a multiprocessor machine. If
 409           you say Y here, the kernel will run on many, but not all,
 410           uniprocessor machines. On a uniprocessor machine, the kernel
 411           will run faster if you say N here.
 412
 413           See also the SMP-HOWTO available at
 414           <http://www.tldp.org/docs.html#howto>.
 415
 416           Even if you don't know what to do here, say Y.
 417
 418 config NR_CPUS
 419         int "Maximum number of CPUs (2-512)"
 420         range 2 512
 421         depends on SMP
 422         default "64"
 423         help
 424           This allows you to specify the maximum number of CPUs which this
 425           kernel will support. The maximum supported value is 512 and the
 426           minimum value which makes sense is 2.
 427
 428           This is purely to save memory - each supported CPU adds
 429           approximately sixteen kilobytes to the kernel image.
 430
 431 config HOTPLUG_CPU
 432         def_bool y
 433         prompt "Support for hot-pluggable CPUs"
 434         depends on SMP
 435         help
 436           Say Y here to be able to turn CPUs off and on. CPUs
 437           can be controlled through /sys/devices/system/cpu/cpu#.
 438           Say N if you want to disable CPU hotplug.
 439
 440 # Some NUMA nodes have memory ranges that span
 441 # other nodes.  Even though a pfn is valid and
 442 # between a node's start and end pfns, it may not
 443 # reside on that node.  See memmap_init_zone()
 444 # for details. <- They meant memory holes!
 445 config NODES_SPAN_OTHER_NODES
 446         def_bool NUMA
 447
 448 config NUMA
 449         bool "NUMA support"
 450         depends on SMP && SCHED_TOPOLOGY
 451         default n
 452         help
 453           Enable NUMA support
 454
 455           This option adds NUMA support to the kernel.
 456
 457           An operation mode can be selected by appending
 458           numa=<method> to the kernel command line.
 459
 460           The default behaviour is identical to appending numa=plain to
 461           the command line. This will create just one node with all
 462           available memory and all CPUs in it.
 463
 464 config NODES_SHIFT
 465         int "Maximum NUMA nodes (as a power of 2)"
 466         range 1 10
 467         depends on NUMA
 468         default "4"
 469         help
 470           Specify the maximum number of NUMA nodes available on the target
 471           system. Increases memory reserved to accommodate various tables.
 472
 473 menu "Select NUMA modes"
 474         depends on NUMA
 475
 476 config NUMA_EMU
 477         bool "NUMA emulation"
 478         default y
 479         help
 480           Numa emulation mode will split the available system memory into
 481           equal chunks which then are distributed over the configured number
 482           of nodes in a round-robin manner.
 483
 484           The number of fake nodes is limited by the number of available memory
 485           chunks (i.e. memory size / fake size) and the number of supported
 486           nodes in the kernel.
 487
 488           The CPUs are assigned to the nodes in a way that partially respects
 489           the original machine topology (if supported by the machine).
 490           Fair distribution of the CPUs is not guaranteed.
 491
 492 config EMU_SIZE
 493         hex "NUMA emulation memory chunk size"
 494         default 0x10000000
 495         range 0x400000 0x100000000
 496         depends on NUMA_EMU
 497         help
 498           Select the default size by which the memory is chopped and then
 499           assigned to emulated NUMA nodes.
 500
 501           This can be overridden by specifying
 502
 503           emu_size=<n>
 504
 505           on the kernel command line where also suffixes K, M, G, and T are
 506           supported.
 507
 508 endmenu
 509
 510 config SCHED_SMT
 511         def_bool n
 512
 513 config SCHED_MC
 514         def_bool n
 515
 516 config SCHED_BOOK
 517         def_bool n
 518
 519 config SCHED_DRAWER
 520         def_bool n
 521
 522 config SCHED_TOPOLOGY
 523         def_bool y
 524         prompt "Topology scheduler support"
 525         depends on SMP
 526         select SCHED_SMT
 527         select SCHED_MC
 528         select SCHED_BOOK
 529         select SCHED_DRAWER
 530         help
 531           Topology scheduler support improves the CPU scheduler's decision
 532           making when dealing with machines that have multi-threading,
 533           multiple cores or multiple books.
 534
 535 source "kernel/Kconfig.hz"
 536
 537 config KEXEC
 538         def_bool y
 539         select KEXEC_CORE
 540
 541 config KEXEC_FILE
 542         bool "kexec file based system call"
 543         select KEXEC_CORE
 544         select BUILD_BIN2C
 545         depends on CRYPTO
 546         depends on CRYPTO_SHA256
 547         depends on CRYPTO_SHA256_S390
 548         help
 549           Enable the kexec file based system call. In contrast to the normal
 550           kexec system call this system call takes file descriptors for the
 551           kernel and initramfs as arguments.
 552
 553 config ARCH_HAS_KEXEC_PURGATORY
 554         def_bool y
 555         depends on KEXEC_FILE
 556
 557 config KEXEC_VERIFY_SIG
 558         bool "Verify kernel signature during kexec_file_load() syscall"
 559         depends on KEXEC_FILE && SYSTEM_DATA_VERIFICATION
 560         help
 561           This option makes kernel signature verification mandatory for
 562           the kexec_file_load() syscall.
 563
 564           In addition to that option, you need to enable signature
 565           verification for the corresponding kernel image type being
 566           loaded in order for this to work.
 567
 568 config ARCH_RANDOM
 569         def_bool y
 570         prompt "s390 architectural random number generation API"
 571         help
 572           Enable the s390 architectural random number generation API
 573           to provide random data for all consumers within the Linux
 574           kernel.
 575
 576           When enabled the arch_random_* functions declared in linux/random.h
 577           are implemented. The implementation is based on the s390 CPACF
 578           instruction subfunction TRNG which provides a real true random
 579           number generator.
 580
 581           If unsure, say Y.
 582
 583 config KERNEL_NOBP
 584         def_bool n
 585         prompt "Enable modified branch prediction for the kernel by default"
 586         help
 587           If this option is selected the kernel will switch to a modified
 588           branch prediction mode if the firmware interface is available.
 589           The modified branch prediction mode improves the behaviour in
 590           regard to speculative execution.
 591
 592           With the option enabled the kernel parameter "nobp=0" or "nospec"
 593           can be used to run the kernel in the normal branch prediction mode.
 594
 595           With the option disabled the modified branch prediction mode is
 596           enabled with the "nobp=1" kernel parameter.
 597
 598           If unsure, say N.
 599
 600 config EXPOLINE
 601         def_bool n
 602         prompt "Avoid speculative indirect branches in the kernel"
 603         help
 604           Compile the kernel with the expoline compiler options to guard
 605           against kernel-to-user data leaks by avoiding speculative indirect
 606           branches.
 607           Requires a compiler with -mindirect-branch=thunk support for full
 608           protection. The kernel may run slower.
 609
 610           If unsure, say N.
 611
 612 choice
 613         prompt "Expoline default"
 614         depends on EXPOLINE
 615         default EXPOLINE_FULL
 616
 617 config EXPOLINE_OFF
 618         bool "spectre_v2=off"
 619
 620 config EXPOLINE_AUTO
 621         bool "spectre_v2=auto"
 622
 623 config EXPOLINE_FULL
 624         bool "spectre_v2=on"
 625
 626 endchoice
 627
 628 config RELOCATABLE
 629         bool "Build a relocatable kernel"
 630         select MODULE_REL_CRCS if MODVERSIONS
 631         default y
 632         help
 633           This builds a kernel image that retains relocation information
 634           so it can be loaded at an arbitrary address.
 635           The kernel is linked as a position-independent executable (PIE)
 636           and contains dynamic relocations which are processed early in the
 637           bootup process.
 638           The relocations make the kernel image about 15% larger (compressed
 639           10%), but are discarded at runtime.
 640
 641 config RANDOMIZE_BASE
 642         bool "Randomize the address of the kernel image (KASLR)"
 643         depends on RELOCATABLE
 644         default y
 645         help
 646           In support of Kernel Address Space Layout Randomization (KASLR),
 647           this randomizes the address at which the kernel image is loaded,
 648           as a security feature that deters exploit attempts relying on
 649           knowledge of the location of kernel internals.
 650
 651 endmenu
 652
 653 menu "Memory setup"
 654
 655 config ARCH_SPARSEMEM_ENABLE
 656         def_bool y
 657         select SPARSEMEM_VMEMMAP_ENABLE
 658         select SPARSEMEM_VMEMMAP
 659
 660 config ARCH_SPARSEMEM_DEFAULT
 661         def_bool y
 662
 663 config ARCH_SELECT_MEMORY_MODEL
 664         def_bool y
 665
 666 config ARCH_ENABLE_MEMORY_HOTPLUG
 667         def_bool y if SPARSEMEM
 668
 669 config ARCH_ENABLE_MEMORY_HOTREMOVE
 670         def_bool y
 671
 672 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 673         def_bool y
 674
 675 config FORCE_MAX_ZONEORDER
 676         int
 677         default "9"
 678
 679 config MAX_PHYSMEM_BITS
 680         int "Maximum size of supported physical memory in bits (42-53)"
 681         range 42 53
 682         default "46"
 683         help
 684           This option specifies the maximum supported size of physical memory
 685           in bits. Supported is any size between 2^42 (4TB) and 2^53 (8PB).
 686           Increasing the number of bits also increases the kernel image size.
 687           By default 46 bits (64TB) are supported.
 688
 689 config PACK_STACK
 690         def_bool y
 691         prompt "Pack kernel stack"
 692         help
 693           This option enables the compiler option -mkernel-backchain if it
 694           is available. If the option is available the compiler supports
 695           the new stack layout which dramatically reduces the minimum stack
 696           frame size. With an old compiler a non-leaf function needs a
 697           minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
 698           -mkernel-backchain the minimum size drops to 16 byte on 31 bit
 699           and 24 byte on 64 bit.
 700
 701           Say Y if you are unsure.
 702
 703 config CHECK_STACK
 704         def_bool y
 705         depends on !VMAP_STACK
 706         prompt "Detect kernel stack overflow"
 707         help
 708           This option enables the compiler option -mstack-guard and
 709           -mstack-size if they are available. If the compiler supports them
 710           it will emit additional code to each function prolog to trigger
 711           an illegal operation if the kernel stack is about to overflow.
 712
 713           Say N if you are unsure.
 714
 715 config STACK_GUARD
 716         int "Size of the guard area (128-1024)"
 717         range 128 1024
 718         depends on CHECK_STACK
 719         default "256"
 720         help
 721           This allows you to specify the size of the guard area at the lower
 722           end of the kernel stack. If the kernel stack points into the guard
 723           area on function entry an illegal operation is triggered. The size
 724           needs to be a power of 2. Please keep in mind that the size of an
 725           interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
 726           The minimum size for the stack guard should be 256 for 31 bit and
 727           512 for 64 bit.
 728
 729 config WARN_DYNAMIC_STACK
 730         def_bool n
 731         prompt "Emit compiler warnings for function with dynamic stack usage"
 732         help
 733           This option enables the compiler option -mwarn-dynamicstack. If the
 734           compiler supports this options generates warnings for functions
 735           that dynamically allocate stack space using alloca.
 736
 737           Say N if you are unsure.
 738
 739 endmenu
 740
 741 menu "I/O subsystem"
 742
 743 config QDIO
 744         def_tristate y
 745         prompt "QDIO support"
 746         ---help---
 747           This driver provides the Queued Direct I/O base support for
 748           IBM System z.
 749
 750           To compile this driver as a module, choose M here: the
 751           module will be called qdio.
 752
 753           If unsure, say Y.
 754
 755 if PCI
 756
 757 config PCI_NR_FUNCTIONS
 758         int "Maximum number of PCI functions (1-4096)"
 759         range 1 4096
 760         default "128"
 761         help
 762           This allows you to specify the maximum number of PCI functions which
 763           this kernel will support.
 764
 765 endif   # PCI
 766
 767 config HAS_IOMEM
 768         def_bool PCI
 769
 770 config CHSC_SCH
 771         def_tristate m
 772         prompt "Support for CHSC subchannels"
 773         help
 774           This driver allows usage of CHSC subchannels. A CHSC subchannel
 775           is usually present on LPAR only.
 776           The driver creates a device /dev/chsc, which may be used to
 777           obtain I/O configuration information about the machine and
 778           to issue asynchronous chsc commands (DANGEROUS).
 779           You will usually only want to use this interface on a special
 780           LPAR designated for system management.
 781
 782           To compile this driver as a module, choose M here: the
 783           module will be called chsc_sch.
 784
 785           If unsure, say N.
 786
 787 config SCM_BUS
 788         def_bool y
 789         prompt "SCM bus driver"
 790         help
 791           Bus driver for Storage Class Memory.
 792
 793 config EADM_SCH
 794         def_tristate m
 795         prompt "Support for EADM subchannels"
 796         depends on SCM_BUS
 797         help
 798           This driver allows usage of EADM subchannels. EADM subchannels act
 799           as a communication vehicle for SCM increments.
 800
 801           To compile this driver as a module, choose M here: the
 802           module will be called eadm_sch.
 803
 804 config VFIO_CCW
 805         def_tristate n
 806         prompt "Support for VFIO-CCW subchannels"
 807         depends on S390_CCW_IOMMU && VFIO_MDEV
 808         help
 809           This driver allows usage of I/O subchannels via VFIO-CCW.
 810
 811           To compile this driver as a module, choose M here: the
 812           module will be called vfio_ccw.
 813
 814 config VFIO_AP
 815         def_tristate n
 816         prompt "VFIO support for AP devices"
 817         depends on S390_AP_IOMMU && VFIO_MDEV_DEVICE && KVM
 818         help
 819                 This driver grants access to Adjunct Processor (AP) devices
 820                 via the VFIO mediated device interface.
 821
 822                 To compile this driver as a module, choose M here: the module
 823                 will be called vfio_ap.
 824
 825 endmenu
 826
 827 menu "Dump support"
 828
 829 config CRASH_DUMP
 830         bool "kernel crash dumps"
 831         depends on SMP
 832         select KEXEC
 833         help
 834           Generate crash dump after being started by kexec.
 835           Crash dump kernels are loaded in the main kernel with kexec-tools
 836           into a specially reserved region and then later executed after
 837           a crash by kdump/kexec.
 838           Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
 839           This option also enables s390 zfcpdump.
 840           See also <file:Documentation/s390/zfcpdump.txt>
 841
 842 endmenu
 843
 844 config SECCOMP
 845         def_bool y
 846         prompt "Enable seccomp to safely compute untrusted bytecode"
 847         depends on PROC_FS
 848         help
 849           This kernel feature is useful for number crunching applications
 850           that may need to compute untrusted bytecode during their
 851           execution. By using pipes or other transports made available to
 852           the process as file descriptors supporting the read/write
 853           syscalls, it's possible to isolate those applications in
 854           their own address space using seccomp. Once seccomp is
 855           enabled via /proc/<pid>/seccomp, it cannot be disabled
 856           and the task is only allowed to execute a few safe syscalls
 857           defined by each seccomp mode.
 858
 859           If unsure, say Y.
 860
 861 menu "Power Management"
 862
 863 config ARCH_HIBERNATION_POSSIBLE
 864         def_bool y
 865
 866 source "kernel/power/Kconfig"
 867
 868 endmenu
 869
 870 config CCW
 871         def_bool y
 872
 873 config HAVE_PNETID
 874         tristate
 875         default (SMC || CCWGROUP)
 876
 877 menu "Virtualization"
 878
 879 config PROTECTED_VIRTUALIZATION_GUEST
 880         def_bool n
 881         prompt "Protected virtualization guest support"
 882         help
 883           Select this option, if you want to be able to run this
 884           kernel as a protected virtualization KVM guest.
 885           Protected virtualization capable machines have a mini hypervisor
 886           located at machine level (an ultravisor). With help of the
 887           Ultravisor, KVM will be able to run "protected" VMs, special
 888           VMs whose memory and management data are unavailable to KVM.
 889
 890 config PFAULT
 891         def_bool y
 892         prompt "Pseudo page fault support"
 893         help
 894           Select this option, if you want to use PFAULT pseudo page fault
 895           handling under VM. If running native or in LPAR, this option
 896           has no effect. If your VM does not support PFAULT, PAGEEX
 897           pseudo page fault handling will be used.
 898           Note that VM 4.2 supports PFAULT but has a bug in its
 899           implementation that causes some problems.
 900           Everybody who wants to run Linux under VM != VM4.2 should select
 901           this option.
 902
 903 config CMM
 904         def_tristate n
 905         prompt "Cooperative memory management"
 906         help
 907           Select this option, if you want to enable the kernel interface
 908           to reduce the memory size of the system. This is accomplished
 909           by allocating pages of memory and put them "on hold". This only
 910           makes sense for a system running under VM where the unused pages
 911           will be reused by VM for other guest systems. The interface
 912           allows an external monitor to balance memory of many systems.
 913           Everybody who wants to run Linux under VM should select this
 914           option.
 915
 916 config CMM_IUCV
 917         def_bool y
 918         prompt "IUCV special message interface to cooperative memory management"
 919         depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
 920         help
 921           Select this option to enable the special message interface to
 922           the cooperative memory management.
 923
 924 config APPLDATA_BASE
 925         def_bool n
 926         prompt "Linux - VM Monitor Stream, base infrastructure"
 927         depends on PROC_FS
 928         help
 929           This provides a kernel interface for creating and updating z/VM APPLDATA
 930           monitor records. The monitor records are updated at certain time
 931           intervals, once the timer is started.
 932           Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
 933           i.e. enables or disables monitoring on the Linux side.
 934           A custom interval value (in seconds) can be written to
 935           /proc/appldata/interval.
 936
 937           Defaults are 60 seconds interval and timer off.
 938           The /proc entries can also be read from, showing the current settings.
 939
 940 config APPLDATA_MEM
 941         def_tristate m
 942         prompt "Monitor memory management statistics"
 943         depends on APPLDATA_BASE && VM_EVENT_COUNTERS
 944         help
 945           This provides memory management related data to the Linux - VM Monitor
 946           Stream, like paging/swapping rate, memory utilisation, etc.
 947           Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
 948           APPLDATA monitor record, i.e. enables or disables monitoring this record
 949           on the z/VM side.
 950
 951           Default is disabled.
 952           The /proc entry can also be read from, showing the current settings.
 953
 954           This can also be compiled as a module, which will be called
 955           appldata_mem.o.
 956
 957 config APPLDATA_OS
 958         def_tristate m
 959         prompt "Monitor OS statistics"
 960         depends on APPLDATA_BASE
 961         help
 962           This provides OS related data to the Linux - VM Monitor Stream, like
 963           CPU utilisation, etc.
 964           Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
 965           APPLDATA monitor record, i.e. enables or disables monitoring this record
 966           on the z/VM side.
 967
 968           Default is disabled.
 969           This can also be compiled as a module, which will be called
 970           appldata_os.o.
 971
 972 config APPLDATA_NET_SUM
 973         def_tristate m
 974         prompt "Monitor overall network statistics"
 975         depends on APPLDATA_BASE && NET
 976         help
 977           This provides network related data to the Linux - VM Monitor Stream,
 978           currently there is only a total sum of network I/O statistics, no
 979           per-interface data.
 980           Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
 981           APPLDATA monitor record, i.e. enables or disables monitoring this record
 982           on the z/VM side.
 983
 984           Default is disabled.
 985           This can also be compiled as a module, which will be called
 986           appldata_net_sum.o.
 987
 988 config S390_HYPFS_FS
 989         def_bool y
 990         prompt "s390 hypervisor file system support"
 991         select SYS_HYPERVISOR
 992         help
 993           This is a virtual file system intended to provide accounting
 994           information in an s390 hypervisor environment.
 995
 996 source "arch/s390/kvm/Kconfig"
 997
 998 config S390_GUEST
 999         def_bool y
1000         prompt "s390 support for virtio devices"
1001         select TTY
1002         select VIRTUALIZATION
1003         select VIRTIO
1004         select VIRTIO_CONSOLE
1005         help
1006           Enabling this option adds support for virtio based paravirtual device
1007           drivers on s390.
1008
1009           Select this option if you want to run the kernel as a guest under
1010           the KVM hypervisor.
1011
1012 endmenu