xref: /openbmc/linux/arch/s390/Kconfig (revision 5b4cb650)
1# SPDX-License-Identifier: GPL-2.0
2config MMU
3	def_bool y
4
5config ZONE_DMA
6	def_bool y
7
8config CPU_BIG_ENDIAN
9	def_bool y
10
11config LOCKDEP_SUPPORT
12	def_bool y
13
14config STACKTRACE_SUPPORT
15	def_bool y
16
17config RWSEM_GENERIC_SPINLOCK
18	bool
19
20config RWSEM_XCHGADD_ALGORITHM
21	def_bool y
22
23config ARCH_HAS_ILOG2_U32
24	def_bool n
25
26config ARCH_HAS_ILOG2_U64
27	def_bool n
28
29config GENERIC_HWEIGHT
30	def_bool y
31
32config GENERIC_BUG
33	def_bool y if BUG
34
35config GENERIC_BUG_RELATIVE_POINTERS
36	def_bool y
37
38config GENERIC_LOCKBREAK
39	def_bool y if SMP && PREEMPT
40
41config PGSTE
42	def_bool y if KVM
43
44config ARCH_SUPPORTS_DEBUG_PAGEALLOC
45	def_bool y
46
47config AUDIT_ARCH
48	def_bool y
49
50config NO_IOPORT_MAP
51	def_bool y
52
53config PCI_QUIRKS
54	def_bool n
55
56config ARCH_SUPPORTS_UPROBES
57	def_bool y
58
59config KASAN_SHADOW_OFFSET
60	hex
61	depends on KASAN
62	default 0x18000000000000 if KASAN_S390_4_LEVEL_PAGING
63	default 0x30000000000
64
65config S390
66	def_bool y
67	select ARCH_BINFMT_ELF_STATE
68	select ARCH_HAS_DEVMEM_IS_ALLOWED
69	select ARCH_HAS_ELF_RANDOMIZE
70	select ARCH_HAS_FORTIFY_SOURCE
71	select ARCH_HAS_GCOV_PROFILE_ALL
72	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
73	select ARCH_HAS_KCOV
74	select ARCH_HAS_PTE_SPECIAL
75	select ARCH_HAS_SET_MEMORY
76	select ARCH_HAS_STRICT_KERNEL_RWX
77	select ARCH_HAS_STRICT_MODULE_RWX
78	select ARCH_HAS_UBSAN_SANITIZE_ALL
79	select ARCH_HAVE_NMI_SAFE_CMPXCHG
80	select ARCH_INLINE_READ_LOCK
81	select ARCH_INLINE_READ_LOCK_BH
82	select ARCH_INLINE_READ_LOCK_IRQ
83	select ARCH_INLINE_READ_LOCK_IRQSAVE
84	select ARCH_INLINE_READ_TRYLOCK
85	select ARCH_INLINE_READ_UNLOCK
86	select ARCH_INLINE_READ_UNLOCK_BH
87	select ARCH_INLINE_READ_UNLOCK_IRQ
88	select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
89	select ARCH_INLINE_SPIN_LOCK
90	select ARCH_INLINE_SPIN_LOCK_BH
91	select ARCH_INLINE_SPIN_LOCK_IRQ
92	select ARCH_INLINE_SPIN_LOCK_IRQSAVE
93	select ARCH_INLINE_SPIN_TRYLOCK
94	select ARCH_INLINE_SPIN_TRYLOCK_BH
95	select ARCH_INLINE_SPIN_UNLOCK
96	select ARCH_INLINE_SPIN_UNLOCK_BH
97	select ARCH_INLINE_SPIN_UNLOCK_IRQ
98	select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
99	select ARCH_INLINE_WRITE_LOCK
100	select ARCH_INLINE_WRITE_LOCK_BH
101	select ARCH_INLINE_WRITE_LOCK_IRQ
102	select ARCH_INLINE_WRITE_LOCK_IRQSAVE
103	select ARCH_INLINE_WRITE_TRYLOCK
104	select ARCH_INLINE_WRITE_UNLOCK
105	select ARCH_INLINE_WRITE_UNLOCK_BH
106	select ARCH_INLINE_WRITE_UNLOCK_IRQ
107	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
108	select ARCH_SAVE_PAGE_KEYS if HIBERNATION
109	select ARCH_SUPPORTS_ATOMIC_RMW
110	select ARCH_SUPPORTS_NUMA_BALANCING
111	select ARCH_USE_BUILTIN_BSWAP
112	select ARCH_USE_CMPXCHG_LOCKREF
113	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
114	select ARCH_WANT_IPC_PARSE_VERSION
115	select BUILDTIME_EXTABLE_SORT
116	select CLONE_BACKWARDS2
117	select DYNAMIC_FTRACE if FUNCTION_TRACER
118	select GENERIC_CLOCKEVENTS
119	select GENERIC_CPU_AUTOPROBE
120	select GENERIC_CPU_DEVICES if !SMP
121	select GENERIC_CPU_VULNERABILITIES
122	select GENERIC_FIND_FIRST_BIT
123	select GENERIC_SMP_IDLE_THREAD
124	select GENERIC_TIME_VSYSCALL
125	select HAVE_ALIGNED_STRUCT_PAGE if SLUB
126	select HAVE_ARCH_AUDITSYSCALL
127	select HAVE_ARCH_JUMP_LABEL
128	select HAVE_ARCH_JUMP_LABEL_RELATIVE
129	select HAVE_ARCH_KASAN
130	select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
131	select HAVE_ARCH_SECCOMP_FILTER
132	select HAVE_ARCH_SOFT_DIRTY
133	select HAVE_ARCH_TRACEHOOK
134	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
135	select HAVE_ARCH_VMAP_STACK
136	select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
137	select HAVE_CMPXCHG_DOUBLE
138	select HAVE_CMPXCHG_LOCAL
139	select HAVE_COPY_THREAD_TLS
140	select HAVE_DEBUG_KMEMLEAK
141	select HAVE_DMA_CONTIGUOUS
142	select HAVE_DYNAMIC_FTRACE
143	select HAVE_DYNAMIC_FTRACE_WITH_REGS
144	select HAVE_EFFICIENT_UNALIGNED_ACCESS
145	select HAVE_FENTRY
146	select HAVE_FTRACE_MCOUNT_RECORD
147	select HAVE_FUNCTION_GRAPH_TRACER
148	select HAVE_FUNCTION_TRACER
149	select HAVE_FUTEX_CMPXCHG if FUTEX
150	select HAVE_GCC_PLUGINS
151	select HAVE_KERNEL_BZIP2
152	select HAVE_KERNEL_GZIP
153	select HAVE_KERNEL_LZ4
154	select HAVE_KERNEL_LZMA
155	select HAVE_KERNEL_LZO
156	select HAVE_KERNEL_UNCOMPRESSED
157	select HAVE_KERNEL_XZ
158	select HAVE_KPROBES
159	select HAVE_KRETPROBES
160	select HAVE_KVM
161	select HAVE_LIVEPATCH
162	select HAVE_PERF_REGS
163	select HAVE_PERF_USER_STACK_DUMP
164	select HAVE_MEMBLOCK_NODE_MAP
165	select HAVE_MEMBLOCK_PHYS_MAP
166	select HAVE_MOD_ARCH_SPECIFIC
167	select HAVE_NOP_MCOUNT
168	select HAVE_OPROFILE
169	select HAVE_PCI
170	select HAVE_PERF_EVENTS
171	select HAVE_REGS_AND_STACK_ACCESS_API
172	select HAVE_RSEQ
173	select HAVE_SYSCALL_TRACEPOINTS
174	select HAVE_VIRT_CPU_ACCOUNTING
175	select IOMMU_HELPER		if PCI
176	select IOMMU_SUPPORT		if PCI
177	select MODULES_USE_ELF_RELA
178	select NEED_DMA_MAP_STATE	if PCI
179	select NEED_SG_DMA_LENGTH	if PCI
180	select OLD_SIGACTION
181	select OLD_SIGSUSPEND3
182	select PCI_DOMAINS		if PCI
183	select PCI_MSI			if PCI
184	select SPARSE_IRQ
185	select SYSCTL_EXCEPTION_TRACE
186	select THREAD_INFO_IN_TASK
187	select TTY
188	select VIRT_CPU_ACCOUNTING
189	select ARCH_HAS_SCALED_CPUTIME
190	select VIRT_TO_BUS
191	select HAVE_NMI
192
193
194config SCHED_OMIT_FRAME_POINTER
195	def_bool y
196
197config PGTABLE_LEVELS
198	int
199	default 5
200
201source "kernel/livepatch/Kconfig"
202
203menu "Processor type and features"
204
205config HAVE_MARCH_Z900_FEATURES
206	def_bool n
207
208config HAVE_MARCH_Z990_FEATURES
209	def_bool n
210	select HAVE_MARCH_Z900_FEATURES
211
212config HAVE_MARCH_Z9_109_FEATURES
213	def_bool n
214	select HAVE_MARCH_Z990_FEATURES
215
216config HAVE_MARCH_Z10_FEATURES
217	def_bool n
218	select HAVE_MARCH_Z9_109_FEATURES
219
220config HAVE_MARCH_Z196_FEATURES
221	def_bool n
222	select HAVE_MARCH_Z10_FEATURES
223
224config HAVE_MARCH_ZEC12_FEATURES
225	def_bool n
226	select HAVE_MARCH_Z196_FEATURES
227
228config HAVE_MARCH_Z13_FEATURES
229	def_bool n
230	select HAVE_MARCH_ZEC12_FEATURES
231
232config HAVE_MARCH_Z14_FEATURES
233	def_bool n
234	select HAVE_MARCH_Z13_FEATURES
235
236choice
237	prompt "Processor type"
238	default MARCH_Z196
239
240config MARCH_Z900
241	bool "IBM zSeries model z800 and z900"
242	select HAVE_MARCH_Z900_FEATURES
243	help
244	  Select this to enable optimizations for model z800/z900 (2064 and
245	  2066 series). This will enable some optimizations that are not
246	  available on older ESA/390 (31 Bit) only CPUs.
247
248config MARCH_Z990
249	bool "IBM zSeries model z890 and z990"
250	select HAVE_MARCH_Z990_FEATURES
251	help
252	  Select this to enable optimizations for model z890/z990 (2084 and
253	  2086 series). The kernel will be slightly faster but will not work
254	  on older machines.
255
256config MARCH_Z9_109
257	bool "IBM System z9"
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
264config 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
272config 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
280config 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
288config 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
296config 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
304endchoice
305
306config MARCH_Z900_TUNE
307	def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT
308
309config MARCH_Z990_TUNE
310	def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT
311
312config MARCH_Z9_109_TUNE
313	def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT
314
315config MARCH_Z10_TUNE
316	def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT
317
318config MARCH_Z196_TUNE
319	def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT
320
321config MARCH_ZEC12_TUNE
322	def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT
323
324config MARCH_Z13_TUNE
325	def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT
326
327config MARCH_Z14_TUNE
328	def_bool TUNE_Z14 || MARCH_Z14 && TUNE_DEFAULT
329
330choice
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
341config 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
347config TUNE_Z900
348	bool "IBM zSeries model z800 and z900"
349
350config TUNE_Z990
351	bool "IBM zSeries model z890 and z990"
352
353config TUNE_Z9_109
354	bool "IBM System z9"
355
356config TUNE_Z10
357	bool "IBM System z10"
358
359config TUNE_Z196
360	bool "IBM zEnterprise 114 and 196"
361
362config TUNE_ZEC12
363	bool "IBM zBC12 and zEC12"
364
365config TUNE_Z13
366	bool "IBM z13"
367
368config TUNE_Z14
369	bool "IBM z14"
370
371endchoice
372
373config 64BIT
374	def_bool y
375
376config COMPAT
377	def_bool y
378	prompt "Kernel support for 31 bit emulation"
379	select COMPAT_BINFMT_ELF if BINFMT_ELF
380	select ARCH_WANT_OLD_COMPAT_IPC
381	select COMPAT_OLD_SIGACTION
382	depends on MULTIUSER
383	help
384	  Select this option if you want to enable your system kernel to
385	  handle system-calls from ELF binaries for 31 bit ESA.  This option
386	  (and some other stuff like libraries and such) is needed for
387	  executing 31 bit applications.  It is safe to say "Y".
388
389config SYSVIPC_COMPAT
390	def_bool y if COMPAT && SYSVIPC
391
392config SMP
393	def_bool y
394	prompt "Symmetric multi-processing support"
395	---help---
396	  This enables support for systems with more than one CPU. If you have
397	  a system with only one CPU, like most personal computers, say N. If
398	  you have a system with more than one CPU, say Y.
399
400	  If you say N here, the kernel will run on uni- and multiprocessor
401	  machines, but will use only one CPU of a multiprocessor machine. If
402	  you say Y here, the kernel will run on many, but not all,
403	  uniprocessor machines. On a uniprocessor machine, the kernel
404	  will run faster if you say N here.
405
406	  See also the SMP-HOWTO available at
407	  <http://www.tldp.org/docs.html#howto>.
408
409	  Even if you don't know what to do here, say Y.
410
411config NR_CPUS
412	int "Maximum number of CPUs (2-512)"
413	range 2 512
414	depends on SMP
415	default "64"
416	help
417	  This allows you to specify the maximum number of CPUs which this
418	  kernel will support. The maximum supported value is 512 and the
419	  minimum value which makes sense is 2.
420
421	  This is purely to save memory - each supported CPU adds
422	  approximately sixteen kilobytes to the kernel image.
423
424config HOTPLUG_CPU
425	def_bool y
426	prompt "Support for hot-pluggable CPUs"
427	depends on SMP
428	help
429	  Say Y here to be able to turn CPUs off and on. CPUs
430	  can be controlled through /sys/devices/system/cpu/cpu#.
431	  Say N if you want to disable CPU hotplug.
432
433# Some NUMA nodes have memory ranges that span
434# other nodes.	Even though a pfn is valid and
435# between a node's start and end pfns, it may not
436# reside on that node.	See memmap_init_zone()
437# for details. <- They meant memory holes!
438config NODES_SPAN_OTHER_NODES
439	def_bool NUMA
440
441config NUMA
442	bool "NUMA support"
443	depends on SMP && SCHED_TOPOLOGY
444	default n
445	help
446	  Enable NUMA support
447
448	  This option adds NUMA support to the kernel.
449
450	  An operation mode can be selected by appending
451	  numa=<method> to the kernel command line.
452
453	  The default behaviour is identical to appending numa=plain to
454	  the command line. This will create just one node with all
455	  available memory and all CPUs in it.
456
457config NODES_SHIFT
458	int "Maximum NUMA nodes (as a power of 2)"
459	range 1 10
460	depends on NUMA
461	default "4"
462	help
463	  Specify the maximum number of NUMA nodes available on the target
464	  system. Increases memory reserved to accommodate various tables.
465
466menu "Select NUMA modes"
467	depends on NUMA
468
469config NUMA_EMU
470	bool "NUMA emulation"
471	default y
472	help
473	  Numa emulation mode will split the available system memory into
474	  equal chunks which then are distributed over the configured number
475	  of nodes in a round-robin manner.
476
477	  The number of fake nodes is limited by the number of available memory
478	  chunks (i.e. memory size / fake size) and the number of supported
479	  nodes in the kernel.
480
481	  The CPUs are assigned to the nodes in a way that partially respects
482	  the original machine topology (if supported by the machine).
483	  Fair distribution of the CPUs is not guaranteed.
484
485config EMU_SIZE
486	hex "NUMA emulation memory chunk size"
487	default 0x10000000
488	range 0x400000 0x100000000
489	depends on NUMA_EMU
490	help
491	  Select the default size by which the memory is chopped and then
492	  assigned to emulated NUMA nodes.
493
494	  This can be overridden by specifying
495
496	  emu_size=<n>
497
498	  on the kernel command line where also suffixes K, M, G, and T are
499	  supported.
500
501endmenu
502
503config SCHED_SMT
504	def_bool n
505
506config SCHED_MC
507	def_bool n
508
509config SCHED_BOOK
510	def_bool n
511
512config SCHED_DRAWER
513	def_bool n
514
515config SCHED_TOPOLOGY
516	def_bool y
517	prompt "Topology scheduler support"
518	depends on SMP
519	select SCHED_SMT
520	select SCHED_MC
521	select SCHED_BOOK
522	select SCHED_DRAWER
523	help
524	  Topology scheduler support improves the CPU scheduler's decision
525	  making when dealing with machines that have multi-threading,
526	  multiple cores or multiple books.
527
528source "kernel/Kconfig.hz"
529
530config KEXEC
531	def_bool y
532	select KEXEC_CORE
533
534config KEXEC_FILE
535	bool "kexec file based system call"
536	select KEXEC_CORE
537	select BUILD_BIN2C
538	depends on CRYPTO
539	depends on CRYPTO_SHA256
540	depends on CRYPTO_SHA256_S390
541	help
542	  Enable the kexec file based system call. In contrast to the normal
543	  kexec system call this system call takes file descriptors for the
544	  kernel and initramfs as arguments.
545
546config ARCH_HAS_KEXEC_PURGATORY
547	def_bool y
548	depends on KEXEC_FILE
549
550config ARCH_RANDOM
551	def_bool y
552	prompt "s390 architectural random number generation API"
553	help
554	  Enable the s390 architectural random number generation API
555	  to provide random data for all consumers within the Linux
556	  kernel.
557
558	  When enabled the arch_random_* functions declared in linux/random.h
559	  are implemented. The implementation is based on the s390 CPACF
560	  instruction subfunction TRNG which provides a real true random
561	  number generator.
562
563	  If unsure, say Y.
564
565config KERNEL_NOBP
566	def_bool n
567	prompt "Enable modified branch prediction for the kernel by default"
568	help
569	  If this option is selected the kernel will switch to a modified
570	  branch prediction mode if the firmware interface is available.
571	  The modified branch prediction mode improves the behaviour in
572	  regard to speculative execution.
573
574	  With the option enabled the kernel parameter "nobp=0" or "nospec"
575	  can be used to run the kernel in the normal branch prediction mode.
576
577	  With the option disabled the modified branch prediction mode is
578	  enabled with the "nobp=1" kernel parameter.
579
580	  If unsure, say N.
581
582config EXPOLINE
583	def_bool n
584	prompt "Avoid speculative indirect branches in the kernel"
585	help
586	  Compile the kernel with the expoline compiler options to guard
587	  against kernel-to-user data leaks by avoiding speculative indirect
588	  branches.
589	  Requires a compiler with -mindirect-branch=thunk support for full
590	  protection. The kernel may run slower.
591
592	  If unsure, say N.
593
594choice
595	prompt "Expoline default"
596	depends on EXPOLINE
597	default EXPOLINE_FULL
598
599config EXPOLINE_OFF
600	bool "spectre_v2=off"
601
602config EXPOLINE_AUTO
603	bool "spectre_v2=auto"
604
605config EXPOLINE_FULL
606	bool "spectre_v2=on"
607
608endchoice
609
610endmenu
611
612menu "Memory setup"
613
614config ARCH_SPARSEMEM_ENABLE
615	def_bool y
616	select SPARSEMEM_VMEMMAP_ENABLE
617	select SPARSEMEM_VMEMMAP
618
619config ARCH_SPARSEMEM_DEFAULT
620	def_bool y
621
622config ARCH_SELECT_MEMORY_MODEL
623	def_bool y
624
625config ARCH_ENABLE_MEMORY_HOTPLUG
626	def_bool y if SPARSEMEM
627
628config ARCH_ENABLE_MEMORY_HOTREMOVE
629	def_bool y
630
631config ARCH_ENABLE_SPLIT_PMD_PTLOCK
632	def_bool y
633
634config FORCE_MAX_ZONEORDER
635	int
636	default "9"
637
638config 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
648config 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
662config 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
674config 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
688config WARN_DYNAMIC_STACK
689	def_bool n
690	prompt "Emit compiler warnings for function with dynamic stack usage"
691	help
692	  This option enables the compiler option -mwarn-dynamicstack. If the
693	  compiler supports this options generates warnings for functions
694	  that dynamically allocate stack space using alloca.
695
696	  Say N if you are unsure.
697
698endmenu
699
700menu "I/O subsystem"
701
702config QDIO
703	def_tristate y
704	prompt "QDIO support"
705	---help---
706	  This driver provides the Queued Direct I/O base support for
707	  IBM System z.
708
709	  To compile this driver as a module, choose M here: the
710	  module will be called qdio.
711
712	  If unsure, say Y.
713
714if PCI
715
716config PCI_NR_FUNCTIONS
717	int "Maximum number of PCI functions (1-4096)"
718	range 1 4096
719	default "128"
720	help
721	  This allows you to specify the maximum number of PCI functions which
722	  this kernel will support.
723
724endif	# PCI
725
726config HAS_IOMEM
727	def_bool PCI
728
729config CHSC_SCH
730	def_tristate m
731	prompt "Support for CHSC subchannels"
732	help
733	  This driver allows usage of CHSC subchannels. A CHSC subchannel
734	  is usually present on LPAR only.
735	  The driver creates a device /dev/chsc, which may be used to
736	  obtain I/O configuration information about the machine and
737	  to issue asynchronous chsc commands (DANGEROUS).
738	  You will usually only want to use this interface on a special
739	  LPAR designated for system management.
740
741	  To compile this driver as a module, choose M here: the
742	  module will be called chsc_sch.
743
744	  If unsure, say N.
745
746config SCM_BUS
747	def_bool y
748	prompt "SCM bus driver"
749	help
750	  Bus driver for Storage Class Memory.
751
752config EADM_SCH
753	def_tristate m
754	prompt "Support for EADM subchannels"
755	depends on SCM_BUS
756	help
757	  This driver allows usage of EADM subchannels. EADM subchannels act
758	  as a communication vehicle for SCM increments.
759
760	  To compile this driver as a module, choose M here: the
761	  module will be called eadm_sch.
762
763config VFIO_CCW
764	def_tristate n
765	prompt "Support for VFIO-CCW subchannels"
766	depends on S390_CCW_IOMMU && VFIO_MDEV
767	help
768	  This driver allows usage of I/O subchannels via VFIO-CCW.
769
770	  To compile this driver as a module, choose M here: the
771	  module will be called vfio_ccw.
772
773config VFIO_AP
774	def_tristate n
775	prompt "VFIO support for AP devices"
776	depends on S390_AP_IOMMU && VFIO_MDEV_DEVICE && KVM
777	help
778		This driver grants access to Adjunct Processor (AP) devices
779		via the VFIO mediated device interface.
780
781		To compile this driver as a module, choose M here: the module
782		will be called vfio_ap.
783
784endmenu
785
786menu "Dump support"
787
788config CRASH_DUMP
789	bool "kernel crash dumps"
790	depends on SMP
791	select KEXEC
792	help
793	  Generate crash dump after being started by kexec.
794	  Crash dump kernels are loaded in the main kernel with kexec-tools
795	  into a specially reserved region and then later executed after
796	  a crash by kdump/kexec.
797	  Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
798	  This option also enables s390 zfcpdump.
799	  See also <file:Documentation/s390/zfcpdump.txt>
800
801endmenu
802
803config SECCOMP
804	def_bool y
805	prompt "Enable seccomp to safely compute untrusted bytecode"
806	depends on PROC_FS
807	help
808	  This kernel feature is useful for number crunching applications
809	  that may need to compute untrusted bytecode during their
810	  execution. By using pipes or other transports made available to
811	  the process as file descriptors supporting the read/write
812	  syscalls, it's possible to isolate those applications in
813	  their own address space using seccomp. Once seccomp is
814	  enabled via /proc/<pid>/seccomp, it cannot be disabled
815	  and the task is only allowed to execute a few safe syscalls
816	  defined by each seccomp mode.
817
818	  If unsure, say Y.
819
820menu "Power Management"
821
822config ARCH_HIBERNATION_POSSIBLE
823	def_bool y
824
825source "kernel/power/Kconfig"
826
827endmenu
828
829config CCW
830	def_bool y
831
832config HAVE_PNETID
833	tristate
834	default (SMC || CCWGROUP)
835
836menu "Virtualization"
837
838config PFAULT
839	def_bool y
840	prompt "Pseudo page fault support"
841	help
842	  Select this option, if you want to use PFAULT pseudo page fault
843	  handling under VM. If running native or in LPAR, this option
844	  has no effect. If your VM does not support PFAULT, PAGEEX
845	  pseudo page fault handling will be used.
846	  Note that VM 4.2 supports PFAULT but has a bug in its
847	  implementation that causes some problems.
848	  Everybody who wants to run Linux under VM != VM4.2 should select
849	  this option.
850
851config CMM
852	def_tristate n
853	prompt "Cooperative memory management"
854	help
855	  Select this option, if you want to enable the kernel interface
856	  to reduce the memory size of the system. This is accomplished
857	  by allocating pages of memory and put them "on hold". This only
858	  makes sense for a system running under VM where the unused pages
859	  will be reused by VM for other guest systems. The interface
860	  allows an external monitor to balance memory of many systems.
861	  Everybody who wants to run Linux under VM should select this
862	  option.
863
864config CMM_IUCV
865	def_bool y
866	prompt "IUCV special message interface to cooperative memory management"
867	depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
868	help
869	  Select this option to enable the special message interface to
870	  the cooperative memory management.
871
872config APPLDATA_BASE
873	def_bool n
874	prompt "Linux - VM Monitor Stream, base infrastructure"
875	depends on PROC_FS
876	help
877	  This provides a kernel interface for creating and updating z/VM APPLDATA
878	  monitor records. The monitor records are updated at certain time
879	  intervals, once the timer is started.
880	  Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
881	  i.e. enables or disables monitoring on the Linux side.
882	  A custom interval value (in seconds) can be written to
883	  /proc/appldata/interval.
884
885	  Defaults are 60 seconds interval and timer off.
886	  The /proc entries can also be read from, showing the current settings.
887
888config APPLDATA_MEM
889	def_tristate m
890	prompt "Monitor memory management statistics"
891	depends on APPLDATA_BASE && VM_EVENT_COUNTERS
892	help
893	  This provides memory management related data to the Linux - VM Monitor
894	  Stream, like paging/swapping rate, memory utilisation, etc.
895	  Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
896	  APPLDATA monitor record, i.e. enables or disables monitoring this record
897	  on the z/VM side.
898
899	  Default is disabled.
900	  The /proc entry can also be read from, showing the current settings.
901
902	  This can also be compiled as a module, which will be called
903	  appldata_mem.o.
904
905config APPLDATA_OS
906	def_tristate m
907	prompt "Monitor OS statistics"
908	depends on APPLDATA_BASE
909	help
910	  This provides OS related data to the Linux - VM Monitor Stream, like
911	  CPU utilisation, etc.
912	  Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
913	  APPLDATA monitor record, i.e. enables or disables monitoring this record
914	  on the z/VM side.
915
916	  Default is disabled.
917	  This can also be compiled as a module, which will be called
918	  appldata_os.o.
919
920config APPLDATA_NET_SUM
921	def_tristate m
922	prompt "Monitor overall network statistics"
923	depends on APPLDATA_BASE && NET
924	help
925	  This provides network related data to the Linux - VM Monitor Stream,
926	  currently there is only a total sum of network I/O statistics, no
927	  per-interface data.
928	  Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
929	  APPLDATA monitor record, i.e. enables or disables monitoring this record
930	  on the z/VM side.
931
932	  Default is disabled.
933	  This can also be compiled as a module, which will be called
934	  appldata_net_sum.o.
935
936config S390_HYPFS_FS
937	def_bool y
938	prompt "s390 hypervisor file system support"
939	select SYS_HYPERVISOR
940	help
941	  This is a virtual file system intended to provide accounting
942	  information in an s390 hypervisor environment.
943
944source "arch/s390/kvm/Kconfig"
945
946config S390_GUEST
947	def_bool y
948	prompt "s390 support for virtio devices"
949	select TTY
950	select VIRTUALIZATION
951	select VIRTIO
952	select VIRTIO_CONSOLE
953	help
954	  Enabling this option adds support for virtio based paravirtual device
955	  drivers on s390.
956
957	  Select this option if you want to run the kernel as a guest under
958	  the KVM hypervisor.
959
960endmenu
961