xref: /openbmc/linux/arch/s390/Kconfig (revision 08f3e087)
1# SPDX-License-Identifier: GPL-2.0
2config MMU
3	def_bool y
4
5config CPU_BIG_ENDIAN
6	def_bool y
7
8config LOCKDEP_SUPPORT
9	def_bool y
10
11config STACKTRACE_SUPPORT
12	def_bool y
13
14config ARCH_HAS_ILOG2_U32
15	def_bool n
16
17config ARCH_HAS_ILOG2_U64
18	def_bool n
19
20config GENERIC_HWEIGHT
21	def_bool y
22
23config GENERIC_BUG
24	def_bool y if BUG
25
26config GENERIC_BUG_RELATIVE_POINTERS
27	def_bool y
28
29config GENERIC_LOCKBREAK
30	def_bool y if PREEMPTION
31
32config PGSTE
33	def_bool y if KVM
34
35config AUDIT_ARCH
36	def_bool y
37
38config NO_IOPORT_MAP
39	def_bool y
40
41config PCI_QUIRKS
42	def_bool n
43
44config ARCH_SUPPORTS_UPROBES
45	def_bool y
46
47config KASAN_SHADOW_OFFSET
48	hex
49	depends on KASAN
50	default 0x18000000000000
51
52config 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
219config SCHED_OMIT_FRAME_POINTER
220	def_bool y
221
222config PGTABLE_LEVELS
223	int
224	default 5
225
226source "kernel/livepatch/Kconfig"
227
228menu "Processor type and features"
229
230config HAVE_MARCH_Z900_FEATURES
231	def_bool n
232
233config HAVE_MARCH_Z990_FEATURES
234	def_bool n
235	select HAVE_MARCH_Z900_FEATURES
236
237config HAVE_MARCH_Z9_109_FEATURES
238	def_bool n
239	select HAVE_MARCH_Z990_FEATURES
240
241config HAVE_MARCH_Z10_FEATURES
242	def_bool n
243	select HAVE_MARCH_Z9_109_FEATURES
244
245config HAVE_MARCH_Z196_FEATURES
246	def_bool n
247	select HAVE_MARCH_Z10_FEATURES
248
249config HAVE_MARCH_ZEC12_FEATURES
250	def_bool n
251	select HAVE_MARCH_Z196_FEATURES
252
253config HAVE_MARCH_Z13_FEATURES
254	def_bool n
255	select HAVE_MARCH_ZEC12_FEATURES
256
257config HAVE_MARCH_Z14_FEATURES
258	def_bool n
259	select HAVE_MARCH_Z13_FEATURES
260
261config HAVE_MARCH_Z15_FEATURES
262	def_bool n
263	select HAVE_MARCH_Z14_FEATURES
264
265choice
266	prompt "Processor type"
267	default MARCH_Z196
268
269config 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
278config 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
287config 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
296config 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
305config 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
314config 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
323config 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
332config 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
341config 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
350endchoice
351
352config MARCH_Z900_TUNE
353	def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT
354
355config MARCH_Z990_TUNE
356	def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT
357
358config MARCH_Z9_109_TUNE
359	def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT
360
361config MARCH_Z10_TUNE
362	def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT
363
364config MARCH_Z196_TUNE
365	def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT
366
367config MARCH_ZEC12_TUNE
368	def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT
369
370config MARCH_Z13_TUNE
371	def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT
372
373config MARCH_Z14_TUNE
374	def_bool TUNE_Z14 || MARCH_Z14 && TUNE_DEFAULT
375
376config MARCH_Z15_TUNE
377	def_bool TUNE_Z15 || MARCH_Z15 && TUNE_DEFAULT
378
379choice
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
390config 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
396config TUNE_Z900
397	bool "IBM zSeries model z800 and z900"
398	depends on $(cc-option,-mtune=z900)
399
400config TUNE_Z990
401	bool "IBM zSeries model z890 and z990"
402	depends on $(cc-option,-mtune=z990)
403
404config TUNE_Z9_109
405	bool "IBM System z9"
406	depends on $(cc-option,-mtune=z9-109)
407
408config TUNE_Z10
409	bool "IBM System z10"
410	depends on $(cc-option,-mtune=z10)
411
412config TUNE_Z196
413	bool "IBM zEnterprise 114 and 196"
414	depends on $(cc-option,-mtune=z196)
415
416config TUNE_ZEC12
417	bool "IBM zBC12 and zEC12"
418	depends on $(cc-option,-mtune=zEC12)
419
420config TUNE_Z13
421	bool "IBM z13s and z13"
422	depends on $(cc-option,-mtune=z13)
423
424config TUNE_Z14
425	bool "IBM z14 ZR1 and z14"
426	depends on $(cc-option,-mtune=z14)
427
428config TUNE_Z15
429	bool "IBM z15"
430	depends on $(cc-option,-mtune=z15)
431
432endchoice
433
434config 64BIT
435	def_bool y
436
437config 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
451config SYSVIPC_COMPAT
452	def_bool y if COMPAT && SYSVIPC
453
454config SMP
455	def_bool y
456
457config 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
469config HOTPLUG_CPU
470	def_bool y
471
472config 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
481config NODES_SHIFT
482	int
483	depends on NUMA
484	default "1"
485
486config SCHED_SMT
487	def_bool n
488
489config SCHED_MC
490	def_bool n
491
492config SCHED_BOOK
493	def_bool n
494
495config SCHED_DRAWER
496	def_bool n
497
498config 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
510source "kernel/Kconfig.hz"
511
512config KEXEC
513	def_bool y
514	select KEXEC_CORE
515
516config 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
528config ARCH_HAS_KEXEC_PURGATORY
529	def_bool y
530	depends on KEXEC_FILE
531
532config 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
543config 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
558config 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
575config 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
587choice
588	prompt "Expoline default"
589	depends on EXPOLINE
590	default EXPOLINE_FULL
591
592config EXPOLINE_OFF
593	bool "spectre_v2=off"
594
595config EXPOLINE_AUTO
596	bool "spectre_v2=auto"
597
598config EXPOLINE_FULL
599	bool "spectre_v2=on"
600
601endchoice
602
603config 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
616config 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
626endmenu
627
628menu "Memory setup"
629
630config ARCH_SPARSEMEM_ENABLE
631	def_bool y
632	select SPARSEMEM_VMEMMAP_ENABLE
633	select SPARSEMEM_VMEMMAP
634
635config ARCH_SPARSEMEM_DEFAULT
636	def_bool y
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
688endmenu
689
690menu "I/O subsystem"
691
692config 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
704if PCI
705
706config 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
714endif # PCI
715
716config HAS_IOMEM
717	def_bool PCI
718
719config 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
736config SCM_BUS
737	def_bool y
738	prompt "SCM bus driver"
739	help
740	  Bus driver for Storage Class Memory.
741
742config 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
753config 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
763config 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
775endmenu
776
777menu "Dump support"
778
779config 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
791endmenu
792
793config CCW
794	def_bool y
795
796config HAVE_PNETID
797	tristate
798	default (SMC || CCWGROUP)
799
800menu "Virtualization"
801
802config 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
814config 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
827config 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
840config 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
848config 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
864config 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
881config 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
896config 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
912config 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
920source "arch/s390/kvm/Kconfig"
921
922config 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
935endmenu
936
937menu "Selftests"
938
939config 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
949endmenu
950