2 # For a description of the syntax of this configuration file,
3 # see Documentation/kbuild/kconfig-language.txt.
17 config LOCKDEP_SUPPORT
20 config STACKTRACE_SUPPORT
23 config HAVE_LATENCYTOP_SUPPORT
26 config RWSEM_GENERIC_SPINLOCK
29 config RWSEM_XCHGADD_ALGORITHM
32 config ARCH_HAS_ILOG2_U32
36 config ARCH_HAS_ILOG2_U64
40 config GENERIC_HWEIGHT
46 config GENERIC_TIME_VSYSCALL
49 config GENERIC_CLOCKEVENTS
63 config GENERIC_LOCKBREAK
66 depends on SMP && PREEMPT
72 config VIRT_CPU_ACCOUNTING
75 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
78 mainmenu "Linux Kernel Configuration"
82 select USE_GENERIC_SMP_HELPERS if SMP
83 select HAVE_SYSCALL_WRAPPERS
84 select HAVE_FUNCTION_TRACER
85 select HAVE_FTRACE_MCOUNT_RECORD
86 select HAVE_DYNAMIC_FTRACE
87 select HAVE_DEFAULT_NO_SPIN_MUTEXES
90 select HAVE_KRETPROBES
91 select HAVE_KVM if 64BIT
92 select HAVE_ARCH_TRACEHOOK
93 select INIT_ALL_POSSIBLE
97 source "kernel/Kconfig.freezer"
101 comment "Processor type and features"
103 source "kernel/time/Kconfig"
108 Select this option if you have a 64 bit IBM zSeries machine
109 and want to use the 64 bit addressing mode.
116 bool "Symmetric multi-processing support"
118 This enables support for systems with more than one CPU. If you have
119 a system with only one CPU, like most personal computers, say N. If
120 you have a system with more than one CPU, say Y.
122 If you say N here, the kernel will run on single and multiprocessor
123 machines, but will use only one CPU of a multiprocessor machine. If
124 you say Y here, the kernel will run on many, but not all,
125 singleprocessor machines. On a singleprocessor machine, the kernel
126 will run faster if you say N here.
128 See also the SMP-HOWTO available at
129 <http://www.tldp.org/docs.html#howto>.
131 Even if you don't know what to do here, say Y.
134 int "Maximum number of CPUs (2-64)"
137 default "32" if !64BIT
138 default "64" if 64BIT
140 This allows you to specify the maximum number of CPUs which this
141 kernel will support. The maximum supported value is 64 and the
142 minimum value which makes sense is 2.
144 This is purely to save memory - each supported CPU adds
145 approximately sixteen kilobytes to the kernel image.
148 bool "Support for hot-pluggable CPUs"
153 Say Y here to be able to turn CPUs off and on. CPUs
154 can be controlled through /sys/devices/system/cpu/cpu#.
155 Say N if you want to disable CPU hotplug.
158 bool "IEEE FPU emulation"
161 This option is required for IEEE compliant floating point arithmetic
162 on older S/390 machines. Say Y unless you know your machine doesn't
166 bool "Kernel support for 31 bit emulation"
168 select COMPAT_BINFMT_ELF
170 Select this option if you want to enable your system kernel to
171 handle system-calls from ELF binaries for 31 bit ESA. This option
172 (and some other stuff like libraries and such) is needed for
173 executing 31 bit applications. It is safe to say "Y".
175 config SYSVIPC_COMPAT
177 depends on COMPAT && SYSVIPC
184 config S390_SWITCH_AMODE
185 bool "Switch kernel/user addressing modes"
187 This option allows to switch the addressing modes of kernel and user
188 space. The kernel parameter switch_amode=on will enable this feature,
189 default is disabled. Enabling this (via kernel parameter) on machines
190 earlier than IBM System z9-109 EC/BC will reduce system performance.
192 Note that this option will also be selected by selecting the execute
193 protection option below. Enabling the execute protection via the
194 noexec kernel parameter will also switch the addressing modes,
195 independent of the switch_amode kernel parameter.
198 config S390_EXEC_PROTECT
199 bool "Data execute protection"
200 select S390_SWITCH_AMODE
202 This option allows to enable a buffer overflow protection for user
203 space programs and it also selects the addressing mode option above.
204 The kernel parameter noexec=on will enable this feature and also
205 switch the addressing modes, default is disabled. Enabling this (via
206 kernel parameter) on machines earlier than IBM System z9-109 EC/BC
207 will reduce system performance.
209 comment "Code generation options"
212 prompt "Processor type"
216 bool "S/390 model G5 and G6"
219 Select this to build a 31 bit kernel that works
220 on all S/390 and zSeries machines.
223 bool "IBM eServer zSeries model z800 and z900"
225 Select this to optimize for zSeries machines. This
226 will enable some optimizations that are not available
227 on older 31 bit only CPUs.
230 bool "IBM eServer zSeries model z890 and z990"
232 Select this enable optimizations for model z890/z990.
233 This will be slightly faster but does not work on
234 older machines such as the z900.
239 Select this to enable optimizations for IBM System z9-109, IBM
240 System z9 Enterprise Class (z9 EC), and IBM System z9 Business
241 Class (z9 BC). The kernel will be slightly faster but will not
242 work on older machines such as the z990, z890, z900, and z800.
245 bool "IBM System z10"
247 Select this to enable optimizations for IBM System z10. The
248 kernel will be slightly faster but will not work on older
249 machines such as the z990, z890, z900, z800, z9-109, z9-ec
255 bool "Pack kernel stack"
257 This option enables the compiler option -mkernel-backchain if it
258 is available. If the option is available the compiler supports
259 the new stack layout which dramatically reduces the minimum stack
260 frame size. With an old compiler a non-leaf function needs a
261 minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
262 -mkernel-backchain the minimum size drops to 16 byte on 31 bit
263 and 24 byte on 64 bit.
265 Say Y if you are unsure.
268 bool "Use 8kb for kernel stack instead of 16kb"
269 depends on PACK_STACK && 64BIT && !LOCKDEP
271 If you say Y here and the compiler supports the -mkernel-backchain
272 option the kernel will use a smaller kernel stack size. The reduced
273 size is 8kb instead of 16kb. This allows to run more threads on a
274 system and reduces the pressure on the memory management for higher
275 order page allocations.
277 Say N if you are unsure.
280 bool "Detect kernel stack overflow"
282 This option enables the compiler option -mstack-guard and
283 -mstack-size if they are available. If the compiler supports them
284 it will emit additional code to each function prolog to trigger
285 an illegal operation if the kernel stack is about to overflow.
287 Say N if you are unsure.
290 int "Size of the guard area (128-1024)"
292 depends on CHECK_STACK
295 This allows you to specify the size of the guard area at the lower
296 end of the kernel stack. If the kernel stack points into the guard
297 area on function entry an illegal operation is triggered. The size
298 needs to be a power of 2. Please keep in mind that the size of an
299 interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
300 The minimum size for the stack guard should be 256 for 31 bit and
304 bool "Emit compiler warnings for function with broken stack usage"
306 This option enables the compiler options -mwarn-framesize and
307 -mwarn-dynamicstack. If the compiler supports these options it
308 will generate warnings for function which either use alloca or
309 create a stack frame bigger than CONFIG_WARN_STACK_SIZE.
311 Say N if you are unsure.
313 config WARN_STACK_SIZE
314 int "Maximum frame size considered safe (128-2048)"
316 depends on WARN_STACK
319 This allows you to specify the maximum frame size a function may
320 have without the compiler complaining about it.
322 config ARCH_POPULATES_NODE_MAP
325 comment "Kernel preemption"
327 source "kernel/Kconfig.preempt"
329 config ARCH_SPARSEMEM_ENABLE
331 select SPARSEMEM_VMEMMAP_ENABLE
332 select SPARSEMEM_VMEMMAP
333 select SPARSEMEM_STATIC if !64BIT
335 config ARCH_SPARSEMEM_DEFAULT
338 config ARCH_SELECT_MEMORY_MODEL
341 config ARCH_ENABLE_MEMORY_HOTPLUG
345 config ARCH_ENABLE_MEMORY_HOTREMOVE
350 comment "I/O subsystem configuration"
353 tristate "QDIO support"
355 This driver provides the Queued Direct I/O base support for
358 To compile this driver as a module, choose M here: the
359 module will be called qdio.
364 tristate "Support for CHSC subchannels"
366 This driver allows usage of CHSC subchannels. A CHSC subchannel
367 is usually present on LPAR only.
368 The driver creates a device /dev/chsc, which may be used to
369 obtain I/O configuration information about the machine and
370 to issue asynchronous chsc commands (DANGEROUS).
371 You will usually only want to use this interface on a special
372 LPAR designated for system management.
374 To compile this driver as a module, choose M here: the
375 module will be called chsc_sch.
382 bool "Builtin IPL record support"
384 If you want to use the produced kernel to IPL directly from a
385 device, you have to merge a bootsector specific to the device
386 into the first bytes of the kernel. You will have to select the
390 prompt "IPL method generated into head.S"
394 Select "tape" if you want to IPL the image from a Tape.
396 Select "vm_reader" if you are running under VM/ESA and want
397 to IPL the image from the emulated card reader.
407 source "fs/Kconfig.binfmt"
409 config FORCE_MAX_ZONEORDER
414 bool "Show crashed user process info"
416 Say Y to print all process fault locations to the console. This is
417 a debugging option; you probably do not want to set it unless you
418 are an S390 port maintainer.
421 bool "Pseudo page fault support"
423 Select this option, if you want to use PFAULT pseudo page fault
424 handling under VM. If running native or in LPAR, this option
425 has no effect. If your VM does not support PFAULT, PAGEEX
426 pseudo page fault handling will be used.
427 Note that VM 4.2 supports PFAULT but has a bug in its
428 implementation that causes some problems.
429 Everybody who wants to run Linux under VM != VM4.2 should select
433 bool "VM shared kernel support"
435 Select this option, if you want to share the text segment of the
436 Linux kernel between different VM guests. This reduces memory
437 usage with lots of guests but greatly increases kernel size.
438 Also if a kernel was IPL'ed from a shared segment the kexec system
440 You should only select this option if you know what you are
441 doing and want to exploit this feature.
444 tristate "Cooperative memory management"
446 Select this option, if you want to enable the kernel interface
447 to reduce the memory size of the system. This is accomplished
448 by allocating pages of memory and put them "on hold". This only
449 makes sense for a system running under VM where the unused pages
450 will be reused by VM for other guest systems. The interface
451 allows an external monitor to balance memory of many systems.
452 Everybody who wants to run Linux under VM should select this
456 bool "/proc interface to cooperative memory management"
459 Select this option to enable the /proc interface to the
460 cooperative memory management.
463 bool "IUCV special message interface to cooperative memory management"
464 depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
466 Select this option to enable the special message interface to
467 the cooperative memory management.
470 bool "Unused page notification"
472 This enables the notification of unused pages to the
473 hypervisor. The ESSA instruction is used to do the states
474 changes between a page that has content and the unused state.
477 bool "Linux - VM Monitor Stream, base infrastructure"
480 This provides a kernel interface for creating and updating z/VM APPLDATA
481 monitor records. The monitor records are updated at certain time
482 intervals, once the timer is started.
483 Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
484 i.e. enables or disables monitoring on the Linux side.
485 A custom interval value (in seconds) can be written to
486 /proc/appldata/interval.
488 Defaults are 60 seconds interval and timer off.
489 The /proc entries can also be read from, showing the current settings.
492 tristate "Monitor memory management statistics"
493 depends on APPLDATA_BASE && VM_EVENT_COUNTERS
495 This provides memory management related data to the Linux - VM Monitor
496 Stream, like paging/swapping rate, memory utilisation, etc.
497 Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
498 APPLDATA monitor record, i.e. enables or disables monitoring this record
502 The /proc entry can also be read from, showing the current settings.
504 This can also be compiled as a module, which will be called
508 tristate "Monitor OS statistics"
509 depends on APPLDATA_BASE
511 This provides OS related data to the Linux - VM Monitor Stream, like
512 CPU utilisation, etc.
513 Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
514 APPLDATA monitor record, i.e. enables or disables monitoring this record
518 This can also be compiled as a module, which will be called
521 config APPLDATA_NET_SUM
522 tristate "Monitor overall network statistics"
523 depends on APPLDATA_BASE && NET
525 This provides network related data to the Linux - VM Monitor Stream,
526 currently there is only a total sum of network I/O statistics, no
528 Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
529 APPLDATA monitor record, i.e. enables or disables monitoring this record
533 This can also be compiled as a module, which will be called
536 source kernel/Kconfig.hz
539 bool "s390 hypervisor file system support"
540 select SYS_HYPERVISOR
543 This is a virtual file system intended to provide accounting
544 information in an s390 hypervisor environment.
547 bool "kexec system call"
549 kexec is a system call that implements the ability to shutdown your
550 current kernel, and to start another kernel. It is like a reboot
551 but is independent of hardware/microcode support.
554 bool "zfcpdump support"
558 Select this option if you want to build an zfcpdump enabled kernel.
559 Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
562 bool "s390 guest support for KVM (EXPERIMENTAL)"
563 depends on 64BIT && EXPERIMENTAL
566 select VIRTIO_CONSOLE
568 Select this option if you want to run the kernel as a guest under
569 the KVM hypervisor. This will add detection for KVM as well as a
570 virtio transport. If KVM is detected, the virtio console will be
574 bool "Enable seccomp to safely compute untrusted bytecode"
578 This kernel feature is useful for number crunching applications
579 that may need to compute untrusted bytecode during their
580 execution. By using pipes or other transports made available to
581 the process as file descriptors supporting the read/write
582 syscalls, it's possible to isolate those applications in
583 their own address space using seccomp. Once seccomp is
584 enabled via /proc/<pid>/seccomp, it cannot be disabled
585 and the task is only allowed to execute a few safe syscalls
586 defined by each seccomp mode.
600 source "drivers/Kconfig"
604 source "arch/s390/Kconfig.debug"
606 source "security/Kconfig"
608 source "crypto/Kconfig"
612 source "arch/s390/kvm/Kconfig"