xref: /linux/arch/s390/Kconfig (revision e5e1bdf0bca8cd16ad39ed2febf6f689d9c07586)
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 ARCH_HAS_ILOG2_U32
18	def_bool n
19
20config ARCH_HAS_ILOG2_U64
21	def_bool n
22
23config GENERIC_HWEIGHT
24	def_bool y
25
26config GENERIC_BUG
27	def_bool y if BUG
28
29config GENERIC_BUG_RELATIVE_POINTERS
30	def_bool y
31
32config GENERIC_LOCKBREAK
33	def_bool y if PREEMPTION
34
35config PGSTE
36	def_bool y if KVM
37
38config AUDIT_ARCH
39	def_bool y
40
41config NO_IOPORT_MAP
42	def_bool y
43
44config PCI_QUIRKS
45	def_bool n
46
47config ARCH_SUPPORTS_UPROBES
48	def_bool y
49
50config KASAN_SHADOW_OFFSET
51	hex
52	depends on KASAN
53	default 0x18000000000000
54
55config S390
56	def_bool y
57	#
58	# Note: keep this list sorted alphabetically
59	#
60	imply IMA_SECURE_AND_OR_TRUSTED_BOOT
61	select ARCH_32BIT_USTAT_F_TINODE
62	select ARCH_BINFMT_ELF_STATE
63	select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM
64	select ARCH_ENABLE_MEMORY_HOTREMOVE
65	select ARCH_ENABLE_SPLIT_PMD_PTLOCK
66	select ARCH_HAS_DEBUG_VM_PGTABLE
67	select ARCH_HAS_DEBUG_WX
68	select ARCH_HAS_DEVMEM_IS_ALLOWED
69	select ARCH_HAS_ELF_RANDOMIZE
70	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
71	select ARCH_HAS_FORTIFY_SOURCE
72	select ARCH_HAS_GCOV_PROFILE_ALL
73	select ARCH_HAS_GIGANTIC_PAGE
74	select ARCH_HAS_KCOV
75	select ARCH_HAS_MEM_ENCRYPT
76	select ARCH_HAS_PTE_SPECIAL
77	select ARCH_HAS_SCALED_CPUTIME
78	select ARCH_HAS_SET_MEMORY
79	select ARCH_HAS_STRICT_KERNEL_RWX
80	select ARCH_HAS_STRICT_MODULE_RWX
81	select ARCH_HAS_SYSCALL_WRAPPER
82	select ARCH_HAS_UBSAN_SANITIZE_ALL
83	select ARCH_HAS_VDSO_DATA
84	select ARCH_HAVE_NMI_SAFE_CMPXCHG
85	select ARCH_INLINE_READ_LOCK
86	select ARCH_INLINE_READ_LOCK_BH
87	select ARCH_INLINE_READ_LOCK_IRQ
88	select ARCH_INLINE_READ_LOCK_IRQSAVE
89	select ARCH_INLINE_READ_TRYLOCK
90	select ARCH_INLINE_READ_UNLOCK
91	select ARCH_INLINE_READ_UNLOCK_BH
92	select ARCH_INLINE_READ_UNLOCK_IRQ
93	select ARCH_INLINE_READ_UNLOCK_IRQRESTORE
94	select ARCH_INLINE_SPIN_LOCK
95	select ARCH_INLINE_SPIN_LOCK_BH
96	select ARCH_INLINE_SPIN_LOCK_IRQ
97	select ARCH_INLINE_SPIN_LOCK_IRQSAVE
98	select ARCH_INLINE_SPIN_TRYLOCK
99	select ARCH_INLINE_SPIN_TRYLOCK_BH
100	select ARCH_INLINE_SPIN_UNLOCK
101	select ARCH_INLINE_SPIN_UNLOCK_BH
102	select ARCH_INLINE_SPIN_UNLOCK_IRQ
103	select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
104	select ARCH_INLINE_WRITE_LOCK
105	select ARCH_INLINE_WRITE_LOCK_BH
106	select ARCH_INLINE_WRITE_LOCK_IRQ
107	select ARCH_INLINE_WRITE_LOCK_IRQSAVE
108	select ARCH_INLINE_WRITE_TRYLOCK
109	select ARCH_INLINE_WRITE_UNLOCK
110	select ARCH_INLINE_WRITE_UNLOCK_BH
111	select ARCH_INLINE_WRITE_UNLOCK_IRQ
112	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
113	select ARCH_STACKWALK
114	select ARCH_SUPPORTS_ATOMIC_RMW
115	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
116	select ARCH_SUPPORTS_NUMA_BALANCING
117	select ARCH_USE_BUILTIN_BSWAP
118	select ARCH_USE_CMPXCHG_LOCKREF
119	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
120	select ARCH_WANT_DEFAULT_BPF_JIT
121	select ARCH_WANT_IPC_PARSE_VERSION
122	select BUILDTIME_TABLE_SORT
123	select CLONE_BACKWARDS2
124	select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
125	select DMA_OPS if PCI
126	select DYNAMIC_FTRACE if FUNCTION_TRACER
127	select GENERIC_ALLOCATOR
128	select GENERIC_CPU_AUTOPROBE
129	select GENERIC_CPU_VULNERABILITIES
130	select GENERIC_ENTRY
131	select GENERIC_FIND_FIRST_BIT
132	select GENERIC_GETTIMEOFDAY
133	select GENERIC_PTDUMP
134	select GENERIC_SMP_IDLE_THREAD
135	select GENERIC_TIME_VSYSCALL
136	select GENERIC_VDSO_TIME_NS
137	select HAVE_ALIGNED_STRUCT_PAGE if SLUB
138	select HAVE_ARCH_AUDITSYSCALL
139	select HAVE_ARCH_JUMP_LABEL
140	select HAVE_ARCH_JUMP_LABEL_RELATIVE
141	select HAVE_ARCH_KASAN
142	select HAVE_ARCH_KASAN_VMALLOC
143	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
144	select HAVE_ARCH_SECCOMP_FILTER
145	select HAVE_ARCH_SOFT_DIRTY
146	select HAVE_ARCH_TRACEHOOK
147	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
148	select HAVE_ARCH_VMAP_STACK
149	select HAVE_ASM_MODVERSIONS
150	select HAVE_CMPXCHG_DOUBLE
151	select HAVE_CMPXCHG_LOCAL
152	select HAVE_DEBUG_KMEMLEAK
153	select HAVE_DMA_CONTIGUOUS
154	select HAVE_DYNAMIC_FTRACE
155	select HAVE_DYNAMIC_FTRACE_WITH_REGS
156	select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
157	select HAVE_EFFICIENT_UNALIGNED_ACCESS
158	select HAVE_FAST_GUP
159	select HAVE_FENTRY
160	select HAVE_FTRACE_MCOUNT_RECORD
161	select HAVE_FUNCTION_ERROR_INJECTION
162	select HAVE_FUNCTION_GRAPH_TRACER
163	select HAVE_FUNCTION_TRACER
164	select HAVE_FUTEX_CMPXCHG if FUTEX
165	select HAVE_GCC_PLUGINS
166	select HAVE_GENERIC_VDSO
167	select HAVE_IOREMAP_PROT if PCI
168	select HAVE_IRQ_EXIT_ON_IRQ_STACK
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 TTY
214	select VIRT_CPU_ACCOUNTING
215	# Note: keep the above list sorted alphabetically
216
217config SCHED_OMIT_FRAME_POINTER
218	def_bool y
219
220config PGTABLE_LEVELS
221	int
222	default 5
223
224source "kernel/livepatch/Kconfig"
225
226menu "Processor type and features"
227
228config HAVE_MARCH_Z900_FEATURES
229	def_bool n
230
231config HAVE_MARCH_Z990_FEATURES
232	def_bool n
233	select HAVE_MARCH_Z900_FEATURES
234
235config HAVE_MARCH_Z9_109_FEATURES
236	def_bool n
237	select HAVE_MARCH_Z990_FEATURES
238
239config HAVE_MARCH_Z10_FEATURES
240	def_bool n
241	select HAVE_MARCH_Z9_109_FEATURES
242
243config HAVE_MARCH_Z196_FEATURES
244	def_bool n
245	select HAVE_MARCH_Z10_FEATURES
246
247config HAVE_MARCH_ZEC12_FEATURES
248	def_bool n
249	select HAVE_MARCH_Z196_FEATURES
250
251config HAVE_MARCH_Z13_FEATURES
252	def_bool n
253	select HAVE_MARCH_ZEC12_FEATURES
254
255config HAVE_MARCH_Z14_FEATURES
256	def_bool n
257	select HAVE_MARCH_Z13_FEATURES
258
259config HAVE_MARCH_Z15_FEATURES
260	def_bool n
261	select HAVE_MARCH_Z14_FEATURES
262
263choice
264	prompt "Processor type"
265	default MARCH_Z196
266
267config MARCH_Z900
268	bool "IBM zSeries model z800 and z900"
269	select HAVE_MARCH_Z900_FEATURES
270	depends on $(cc-option,-march=z900)
271	help
272	  Select this to enable optimizations for model z800/z900 (2064 and
273	  2066 series). This will enable some optimizations that are not
274	  available on older ESA/390 (31 Bit) only CPUs.
275
276config MARCH_Z990
277	bool "IBM zSeries model z890 and z990"
278	select HAVE_MARCH_Z990_FEATURES
279	depends on $(cc-option,-march=z990)
280	help
281	  Select this to enable optimizations for model z890/z990 (2084 and
282	  2086 series). The kernel will be slightly faster but will not work
283	  on older machines.
284
285config MARCH_Z9_109
286	bool "IBM System z9"
287	select HAVE_MARCH_Z9_109_FEATURES
288	depends on $(cc-option,-march=z9-109)
289	help
290	  Select this to enable optimizations for IBM System z9 (2094 and
291	  2096 series). The kernel will be slightly faster but will not work
292	  on older machines.
293
294config MARCH_Z10
295	bool "IBM System z10"
296	select HAVE_MARCH_Z10_FEATURES
297	depends on $(cc-option,-march=z10)
298	help
299	  Select this to enable optimizations for IBM System z10 (2097 and
300	  2098 series). The kernel will be slightly faster but will not work
301	  on older machines.
302
303config MARCH_Z196
304	bool "IBM zEnterprise 114 and 196"
305	select HAVE_MARCH_Z196_FEATURES
306	depends on $(cc-option,-march=z196)
307	help
308	  Select this to enable optimizations for IBM zEnterprise 114 and 196
309	  (2818 and 2817 series). The kernel will be slightly faster but will
310	  not work on older machines.
311
312config MARCH_ZEC12
313	bool "IBM zBC12 and zEC12"
314	select HAVE_MARCH_ZEC12_FEATURES
315	depends on $(cc-option,-march=zEC12)
316	help
317	  Select this to enable optimizations for IBM zBC12 and zEC12 (2828 and
318	  2827 series). The kernel will be slightly faster but will not work on
319	  older machines.
320
321config MARCH_Z13
322	bool "IBM z13s and z13"
323	select HAVE_MARCH_Z13_FEATURES
324	depends on $(cc-option,-march=z13)
325	help
326	  Select this to enable optimizations for IBM z13s and z13 (2965 and
327	  2964 series). The kernel will be slightly faster but will not work on
328	  older machines.
329
330config MARCH_Z14
331	bool "IBM z14 ZR1 and z14"
332	select HAVE_MARCH_Z14_FEATURES
333	depends on $(cc-option,-march=z14)
334	help
335	  Select this to enable optimizations for IBM z14 ZR1 and z14 (3907
336	  and 3906 series). The kernel will be slightly faster but will not
337	  work on older machines.
338
339config MARCH_Z15
340	bool "IBM z15"
341	select HAVE_MARCH_Z15_FEATURES
342	depends on $(cc-option,-march=z15)
343	help
344	  Select this to enable optimizations for IBM z15 (8562
345	  and 8561 series). The kernel will be slightly faster but will not
346	  work on older machines.
347
348endchoice
349
350config MARCH_Z900_TUNE
351	def_bool TUNE_Z900 || MARCH_Z900 && TUNE_DEFAULT
352
353config MARCH_Z990_TUNE
354	def_bool TUNE_Z990 || MARCH_Z990 && TUNE_DEFAULT
355
356config MARCH_Z9_109_TUNE
357	def_bool TUNE_Z9_109 || MARCH_Z9_109 && TUNE_DEFAULT
358
359config MARCH_Z10_TUNE
360	def_bool TUNE_Z10 || MARCH_Z10 && TUNE_DEFAULT
361
362config MARCH_Z196_TUNE
363	def_bool TUNE_Z196 || MARCH_Z196 && TUNE_DEFAULT
364
365config MARCH_ZEC12_TUNE
366	def_bool TUNE_ZEC12 || MARCH_ZEC12 && TUNE_DEFAULT
367
368config MARCH_Z13_TUNE
369	def_bool TUNE_Z13 || MARCH_Z13 && TUNE_DEFAULT
370
371config MARCH_Z14_TUNE
372	def_bool TUNE_Z14 || MARCH_Z14 && TUNE_DEFAULT
373
374config MARCH_Z15_TUNE
375	def_bool TUNE_Z15 || MARCH_Z15 && TUNE_DEFAULT
376
377choice
378	prompt "Tune code generation"
379	default TUNE_DEFAULT
380	help
381	  Cause the compiler to tune (-mtune) the generated code for a machine.
382	  This will make the code run faster on the selected machine but
383	  somewhat slower on other machines.
384	  This option only changes how the compiler emits instructions, not the
385	  selection of instructions itself, so the resulting kernel will run on
386	  all other machines.
387
388config TUNE_DEFAULT
389	bool "Default"
390	help
391	  Tune the generated code for the target processor for which the kernel
392	  will be compiled.
393
394config TUNE_Z900
395	bool "IBM zSeries model z800 and z900"
396	depends on $(cc-option,-mtune=z900)
397
398config TUNE_Z990
399	bool "IBM zSeries model z890 and z990"
400	depends on $(cc-option,-mtune=z990)
401
402config TUNE_Z9_109
403	bool "IBM System z9"
404	depends on $(cc-option,-mtune=z9-109)
405
406config TUNE_Z10
407	bool "IBM System z10"
408	depends on $(cc-option,-mtune=z10)
409
410config TUNE_Z196
411	bool "IBM zEnterprise 114 and 196"
412	depends on $(cc-option,-mtune=z196)
413
414config TUNE_ZEC12
415	bool "IBM zBC12 and zEC12"
416	depends on $(cc-option,-mtune=zEC12)
417
418config TUNE_Z13
419	bool "IBM z13s and z13"
420	depends on $(cc-option,-mtune=z13)
421
422config TUNE_Z14
423	bool "IBM z14 ZR1 and z14"
424	depends on $(cc-option,-mtune=z14)
425
426config TUNE_Z15
427	bool "IBM z15"
428	depends on $(cc-option,-mtune=z15)
429
430endchoice
431
432config 64BIT
433	def_bool y
434
435config COMPAT
436	def_bool y
437	prompt "Kernel support for 31 bit emulation"
438	select ARCH_WANT_OLD_COMPAT_IPC
439	select COMPAT_OLD_SIGACTION
440	select HAVE_UID16
441	depends on MULTIUSER
442	help
443	  Select this option if you want to enable your system kernel to
444	  handle system-calls from ELF binaries for 31 bit ESA.  This option
445	  (and some other stuff like libraries and such) is needed for
446	  executing 31 bit applications.  It is safe to say "Y".
447
448config SYSVIPC_COMPAT
449	def_bool y if COMPAT && SYSVIPC
450
451config SMP
452	def_bool y
453
454config NR_CPUS
455	int "Maximum number of CPUs (2-512)"
456	range 2 512
457	default "64"
458	help
459	  This allows you to specify the maximum number of CPUs which this
460	  kernel will support. The maximum supported value is 512 and the
461	  minimum value which makes sense is 2.
462
463	  This is purely to save memory - each supported CPU adds
464	  approximately sixteen kilobytes to the kernel image.
465
466config HOTPLUG_CPU
467	def_bool y
468
469config NUMA
470	bool "NUMA support"
471	depends on SCHED_TOPOLOGY
472	default n
473	help
474	  Enable NUMA support
475
476	  This option adds NUMA support to the kernel.
477
478config NODES_SHIFT
479	int
480	depends on NEED_MULTIPLE_NODES
481	default "1"
482
483config SCHED_SMT
484	def_bool n
485
486config SCHED_MC
487	def_bool n
488
489config SCHED_BOOK
490	def_bool n
491
492config SCHED_DRAWER
493	def_bool n
494
495config SCHED_TOPOLOGY
496	def_bool y
497	prompt "Topology scheduler support"
498	select SCHED_SMT
499	select SCHED_MC
500	select SCHED_BOOK
501	select SCHED_DRAWER
502	help
503	  Topology scheduler support improves the CPU scheduler's decision
504	  making when dealing with machines that have multi-threading,
505	  multiple cores or multiple books.
506
507source "kernel/Kconfig.hz"
508
509config KEXEC
510	def_bool y
511	select KEXEC_CORE
512
513config KEXEC_FILE
514	bool "kexec file based system call"
515	select KEXEC_CORE
516	select BUILD_BIN2C
517	depends on CRYPTO
518	depends on CRYPTO_SHA256
519	depends on CRYPTO_SHA256_S390
520	help
521	  Enable the kexec file based system call. In contrast to the normal
522	  kexec system call this system call takes file descriptors for the
523	  kernel and initramfs as arguments.
524
525config ARCH_HAS_KEXEC_PURGATORY
526	def_bool y
527	depends on KEXEC_FILE
528
529config KEXEC_SIG
530	bool "Verify kernel signature during kexec_file_load() syscall"
531	depends on KEXEC_FILE && MODULE_SIG_FORMAT
532	help
533	  This option makes kernel signature verification mandatory for
534	  the kexec_file_load() syscall.
535
536	  In addition to that option, you need to enable signature
537	  verification for the corresponding kernel image type being
538	  loaded in order for this to work.
539
540config ARCH_RANDOM
541	def_bool y
542	prompt "s390 architectural random number generation API"
543	help
544	  Enable the s390 architectural random number generation API
545	  to provide random data for all consumers within the Linux
546	  kernel.
547
548	  When enabled the arch_random_* functions declared in linux/random.h
549	  are implemented. The implementation is based on the s390 CPACF
550	  instruction subfunction TRNG which provides a real true random
551	  number generator.
552
553	  If unsure, say Y.
554
555config KERNEL_NOBP
556	def_bool n
557	prompt "Enable modified branch prediction for the kernel by default"
558	help
559	  If this option is selected the kernel will switch to a modified
560	  branch prediction mode if the firmware interface is available.
561	  The modified branch prediction mode improves the behaviour in
562	  regard to speculative execution.
563
564	  With the option enabled the kernel parameter "nobp=0" or "nospec"
565	  can be used to run the kernel in the normal branch prediction mode.
566
567	  With the option disabled the modified branch prediction mode is
568	  enabled with the "nobp=1" kernel parameter.
569
570	  If unsure, say N.
571
572config EXPOLINE
573	def_bool n
574	prompt "Avoid speculative indirect branches in the kernel"
575	help
576	  Compile the kernel with the expoline compiler options to guard
577	  against kernel-to-user data leaks by avoiding speculative indirect
578	  branches.
579	  Requires a compiler with -mindirect-branch=thunk support for full
580	  protection. The kernel may run slower.
581
582	  If unsure, say N.
583
584choice
585	prompt "Expoline default"
586	depends on EXPOLINE
587	default EXPOLINE_FULL
588
589config EXPOLINE_OFF
590	bool "spectre_v2=off"
591
592config EXPOLINE_AUTO
593	bool "spectre_v2=auto"
594
595config EXPOLINE_FULL
596	bool "spectre_v2=on"
597
598endchoice
599
600config RELOCATABLE
601	bool "Build a relocatable kernel"
602	select MODULE_REL_CRCS if MODVERSIONS
603	default y
604	help
605	  This builds a kernel image that retains relocation information
606	  so it can be loaded at an arbitrary address.
607	  The kernel is linked as a position-independent executable (PIE)
608	  and contains dynamic relocations which are processed early in the
609	  bootup process.
610	  The relocations make the kernel image about 15% larger (compressed
611	  10%), but are discarded at runtime.
612
613config RANDOMIZE_BASE
614	bool "Randomize the address of the kernel image (KASLR)"
615	depends on RELOCATABLE
616	default y
617	help
618	  In support of Kernel Address Space Layout Randomization (KASLR),
619	  this randomizes the address at which the kernel image is loaded,
620	  as a security feature that deters exploit attempts relying on
621	  knowledge of the location of kernel internals.
622
623endmenu
624
625menu "Memory setup"
626
627config ARCH_SPARSEMEM_ENABLE
628	def_bool y
629	select SPARSEMEM_VMEMMAP_ENABLE
630	select SPARSEMEM_VMEMMAP
631
632config ARCH_SPARSEMEM_DEFAULT
633	def_bool y
634
635config MAX_PHYSMEM_BITS
636	int "Maximum size of supported physical memory in bits (42-53)"
637	range 42 53
638	default "46"
639	help
640	  This option specifies the maximum supported size of physical memory
641	  in bits. Supported is any size between 2^42 (4TB) and 2^53 (8PB).
642	  Increasing the number of bits also increases the kernel image size.
643	  By default 46 bits (64TB) are supported.
644
645config PACK_STACK
646	def_bool y
647	prompt "Pack kernel stack"
648	help
649	  This option enables the compiler option -mkernel-backchain if it
650	  is available. If the option is available the compiler supports
651	  the new stack layout which dramatically reduces the minimum stack
652	  frame size. With an old compiler a non-leaf function needs a
653	  minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
654	  -mkernel-backchain the minimum size drops to 16 byte on 31 bit
655	  and 24 byte on 64 bit.
656
657	  Say Y if you are unsure.
658
659config CHECK_STACK
660	def_bool y
661	depends on !VMAP_STACK
662	prompt "Detect kernel stack overflow"
663	help
664	  This option enables the compiler option -mstack-guard and
665	  -mstack-size if they are available. If the compiler supports them
666	  it will emit additional code to each function prolog to trigger
667	  an illegal operation if the kernel stack is about to overflow.
668
669	  Say N if you are unsure.
670
671config STACK_GUARD
672	int "Size of the guard area (128-1024)"
673	range 128 1024
674	depends on CHECK_STACK
675	default "256"
676	help
677	  This allows you to specify the size of the guard area at the lower
678	  end of the kernel stack. If the kernel stack points into the guard
679	  area on function entry an illegal operation is triggered. The size
680	  needs to be a power of 2. Please keep in mind that the size of an
681	  interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
682	  The minimum size for the stack guard should be 256 for 31 bit and
683	  512 for 64 bit.
684
685config WARN_DYNAMIC_STACK
686	def_bool n
687	prompt "Emit compiler warnings for function with dynamic stack usage"
688	help
689	  This option enables the compiler option -mwarn-dynamicstack. If the
690	  compiler supports this options generates warnings for functions
691	  that dynamically allocate stack space using alloca.
692
693	  Say N if you are unsure.
694
695endmenu
696
697menu "I/O subsystem"
698
699config QDIO
700	def_tristate y
701	prompt "QDIO support"
702	help
703	  This driver provides the Queued Direct I/O base support for
704	  IBM System z.
705
706	  To compile this driver as a module, choose M here: the
707	  module will be called qdio.
708
709	  If unsure, say Y.
710
711if PCI
712
713config PCI_NR_FUNCTIONS
714	int "Maximum number of PCI functions (1-4096)"
715	range 1 4096
716	default "512"
717	help
718	  This allows you to specify the maximum number of PCI functions which
719	  this kernel will support.
720
721endif # PCI
722
723config HAS_IOMEM
724	def_bool PCI
725
726config CHSC_SCH
727	def_tristate m
728	prompt "Support for CHSC subchannels"
729	help
730	  This driver allows usage of CHSC subchannels. A CHSC subchannel
731	  is usually present on LPAR only.
732	  The driver creates a device /dev/chsc, which may be used to
733	  obtain I/O configuration information about the machine and
734	  to issue asynchronous chsc commands (DANGEROUS).
735	  You will usually only want to use this interface on a special
736	  LPAR designated for system management.
737
738	  To compile this driver as a module, choose M here: the
739	  module will be called chsc_sch.
740
741	  If unsure, say N.
742
743config SCM_BUS
744	def_bool y
745	prompt "SCM bus driver"
746	help
747	  Bus driver for Storage Class Memory.
748
749config EADM_SCH
750	def_tristate m
751	prompt "Support for EADM subchannels"
752	depends on SCM_BUS
753	help
754	  This driver allows usage of EADM subchannels. EADM subchannels act
755	  as a communication vehicle for SCM increments.
756
757	  To compile this driver as a module, choose M here: the
758	  module will be called eadm_sch.
759
760config VFIO_CCW
761	def_tristate n
762	prompt "Support for VFIO-CCW subchannels"
763	depends on S390_CCW_IOMMU && VFIO_MDEV
764	help
765	  This driver allows usage of I/O subchannels via VFIO-CCW.
766
767	  To compile this driver as a module, choose M here: the
768	  module will be called vfio_ccw.
769
770config VFIO_AP
771	def_tristate n
772	prompt "VFIO support for AP devices"
773	depends on S390_AP_IOMMU && VFIO_MDEV_DEVICE && KVM
774	depends on ZCRYPT
775	help
776		This driver grants access to Adjunct Processor (AP) devices
777		via the VFIO mediated device interface.
778
779		To compile this driver as a module, choose M here: the module
780		will be called vfio_ap.
781
782endmenu
783
784menu "Dump support"
785
786config CRASH_DUMP
787	bool "kernel crash dumps"
788	select KEXEC
789	help
790	  Generate crash dump after being started by kexec.
791	  Crash dump kernels are loaded in the main kernel with kexec-tools
792	  into a specially reserved region and then later executed after
793	  a crash by kdump/kexec.
794	  Refer to <file:Documentation/s390/zfcpdump.rst> for more details on this.
795	  This option also enables s390 zfcpdump.
796	  See also <file:Documentation/s390/zfcpdump.rst>
797
798endmenu
799
800config CCW
801	def_bool y
802
803config HAVE_PNETID
804	tristate
805	default (SMC || CCWGROUP)
806
807menu "Virtualization"
808
809config PROTECTED_VIRTUALIZATION_GUEST
810	def_bool n
811	prompt "Protected virtualization guest support"
812	select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
813	help
814	  Select this option, if you want to be able to run this
815	  kernel as a protected virtualization KVM guest.
816	  Protected virtualization capable machines have a mini hypervisor
817	  located at machine level (an ultravisor). With help of the
818	  Ultravisor, KVM will be able to run "protected" VMs, special
819	  VMs whose memory and management data are unavailable to KVM.
820
821config PFAULT
822	def_bool y
823	prompt "Pseudo page fault support"
824	help
825	  Select this option, if you want to use PFAULT pseudo page fault
826	  handling under VM. If running native or in LPAR, this option
827	  has no effect. If your VM does not support PFAULT, PAGEEX
828	  pseudo page fault handling will be used.
829	  Note that VM 4.2 supports PFAULT but has a bug in its
830	  implementation that causes some problems.
831	  Everybody who wants to run Linux under VM != VM4.2 should select
832	  this option.
833
834config CMM
835	def_tristate n
836	prompt "Cooperative memory management"
837	help
838	  Select this option, if you want to enable the kernel interface
839	  to reduce the memory size of the system. This is accomplished
840	  by allocating pages of memory and put them "on hold". This only
841	  makes sense for a system running under VM where the unused pages
842	  will be reused by VM for other guest systems. The interface
843	  allows an external monitor to balance memory of many systems.
844	  Everybody who wants to run Linux under VM should select this
845	  option.
846
847config CMM_IUCV
848	def_bool y
849	prompt "IUCV special message interface to cooperative memory management"
850	depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
851	help
852	  Select this option to enable the special message interface to
853	  the cooperative memory management.
854
855config APPLDATA_BASE
856	def_bool n
857	prompt "Linux - VM Monitor Stream, base infrastructure"
858	depends on PROC_SYSCTL
859	help
860	  This provides a kernel interface for creating and updating z/VM APPLDATA
861	  monitor records. The monitor records are updated at certain time
862	  intervals, once the timer is started.
863	  Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
864	  i.e. enables or disables monitoring on the Linux side.
865	  A custom interval value (in seconds) can be written to
866	  /proc/appldata/interval.
867
868	  Defaults are 60 seconds interval and timer off.
869	  The /proc entries can also be read from, showing the current settings.
870
871config APPLDATA_MEM
872	def_tristate m
873	prompt "Monitor memory management statistics"
874	depends on APPLDATA_BASE && VM_EVENT_COUNTERS
875	help
876	  This provides memory management related data to the Linux - VM Monitor
877	  Stream, like paging/swapping rate, memory utilisation, etc.
878	  Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
879	  APPLDATA monitor record, i.e. enables or disables monitoring this record
880	  on the z/VM side.
881
882	  Default is disabled.
883	  The /proc entry can also be read from, showing the current settings.
884
885	  This can also be compiled as a module, which will be called
886	  appldata_mem.o.
887
888config APPLDATA_OS
889	def_tristate m
890	prompt "Monitor OS statistics"
891	depends on APPLDATA_BASE
892	help
893	  This provides OS related data to the Linux - VM Monitor Stream, like
894	  CPU utilisation, etc.
895	  Writing 1 or 0 to /proc/appldata/os 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	  This can also be compiled as a module, which will be called
901	  appldata_os.o.
902
903config APPLDATA_NET_SUM
904	def_tristate m
905	prompt "Monitor overall network statistics"
906	depends on APPLDATA_BASE && NET
907	help
908	  This provides network related data to the Linux - VM Monitor Stream,
909	  currently there is only a total sum of network I/O statistics, no
910	  per-interface data.
911	  Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
912	  APPLDATA monitor record, i.e. enables or disables monitoring this record
913	  on the z/VM side.
914
915	  Default is disabled.
916	  This can also be compiled as a module, which will be called
917	  appldata_net_sum.o.
918
919config S390_HYPFS_FS
920	def_bool y
921	prompt "s390 hypervisor file system support"
922	select SYS_HYPERVISOR
923	help
924	  This is a virtual file system intended to provide accounting
925	  information in an s390 hypervisor environment.
926
927source "arch/s390/kvm/Kconfig"
928
929config S390_GUEST
930	def_bool y
931	prompt "s390 support for virtio devices"
932	select TTY
933	select VIRTUALIZATION
934	select VIRTIO
935	help
936	  Enabling this option adds support for virtio based paravirtual device
937	  drivers on s390.
938
939	  Select this option if you want to run the kernel as a guest under
940	  the KVM hypervisor.
941
942endmenu
943
944menu "Selftests"
945
946config S390_UNWIND_SELFTEST
947	def_tristate n
948	prompt "Test unwind functions"
949	help
950	  This option enables s390 specific stack unwinder testing kernel
951	  module. This option is not useful for distributions or general
952	  kernels, but only for kernel developers working on architecture code.
953
954	  Say N if you are unsure.
955
956endmenu
957