2 # For a description of the syntax of this configuration file,
3 # see Documentation/kbuild/kconfig-language.txt.
13 config LOCKDEP_SUPPORT
16 config STACKTRACE_SUPPORT
19 config RWSEM_GENERIC_SPINLOCK
22 config RWSEM_XCHGADD_ALGORITHM
25 config ARCH_HAS_ILOG2_U32
29 config ARCH_HAS_ILOG2_U64
33 config GENERIC_HWEIGHT
50 config GENERIC_LOCKBREAK
53 depends on SMP && PREEMPT
55 mainmenu "Linux Kernel Configuration"
66 comment "Processor type and features"
71 Select this option if you have a 64 bit IBM zSeries machine
72 and want to use the 64 bit addressing mode.
79 bool "Symmetric multi-processing support"
81 This enables support for systems with more than one CPU. If you have
82 a system with only one CPU, like most personal computers, say N. If
83 you have a system with more than one CPU, say Y.
85 If you say N here, the kernel will run on single and multiprocessor
86 machines, but will use only one CPU of a multiprocessor machine. If
87 you say Y here, the kernel will run on many, but not all,
88 singleprocessor machines. On a singleprocessor machine, the kernel
89 will run faster if you say N here.
91 See also the SMP-HOWTO available at
92 <http://www.tldp.org/docs.html#howto>.
94 Even if you don't know what to do here, say Y.
97 int "Maximum number of CPUs (2-64)"
102 This allows you to specify the maximum number of CPUs which this
103 kernel will support. The maximum supported value is 64 and the
104 minimum value which makes sense is 2.
106 This is purely to save memory - each supported CPU adds
107 approximately sixteen kilobytes to the kernel image.
110 bool "Support for hot-pluggable CPUs"
115 Say Y here to be able to turn CPUs off and on. CPUs
116 can be controlled through /sys/devices/system/cpu/cpu#.
117 Say N if you want to disable CPU hotplug.
120 bool "IEEE FPU emulation"
123 This option is required for IEEE compliant floating point arithmetic
124 on older S/390 machines. Say Y unless you know your machine doesn't
128 bool "Kernel support for 31 bit emulation"
131 Select this option if you want to enable your system kernel to
132 handle system-calls from ELF binaries for 31 bit ESA. This option
133 (and some other stuff like libraries and such) is needed for
134 executing 31 bit applications. It is safe to say "Y".
136 config SYSVIPC_COMPAT
138 depends on COMPAT && SYSVIPC
145 config S390_SWITCH_AMODE
146 bool "Switch kernel/user addressing modes"
148 This option allows to switch the addressing modes of kernel and user
149 space. The kernel parameter switch_amode=on will enable this feature,
150 default is disabled. Enabling this (via kernel parameter) on machines
151 earlier than IBM System z9-109 EC/BC will reduce system performance.
153 Note that this option will also be selected by selecting the execute
154 protection option below. Enabling the execute protection via the
155 noexec kernel parameter will also switch the addressing modes,
156 independent of the switch_amode kernel parameter.
159 config S390_EXEC_PROTECT
160 bool "Data execute protection"
161 select S390_SWITCH_AMODE
163 This option allows to enable a buffer overflow protection for user
164 space programs and it also selects the addressing mode option above.
165 The kernel parameter noexec=on will enable this feature and also
166 switch the addressing modes, default is disabled. Enabling this (via
167 kernel parameter) on machines earlier than IBM System z9-109 EC/BC
168 will reduce system performance.
170 comment "Code generation options"
173 prompt "Processor type"
177 bool "S/390 model G5 and G6"
180 Select this to build a 31 bit kernel that works
181 on all S/390 and zSeries machines.
184 bool "IBM eServer zSeries model z800 and z900"
186 Select this to optimize for zSeries machines. This
187 will enable some optimizations that are not available
188 on older 31 bit only CPUs.
191 bool "IBM eServer zSeries model z890 and z990"
193 Select this enable optimizations for model z890/z990.
194 This will be slightly faster but does not work on
195 older machines such as the z900.
200 Select this to enable optimizations for IBM System z9-109, IBM
201 System z9 Enterprise Class (z9 EC), and IBM System z9 Business
202 Class (z9 BC). The kernel will be slightly faster but will not
203 work on older machines such as the z990, z890, z900, and z800.
208 bool "Pack kernel stack"
210 This option enables the compiler option -mkernel-backchain if it
211 is available. If the option is available the compiler supports
212 the new stack layout which dramatically reduces the minimum stack
213 frame size. With an old compiler a non-leaf function needs a
214 minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
215 -mkernel-backchain the minimum size drops to 16 byte on 31 bit
216 and 24 byte on 64 bit.
218 Say Y if you are unsure.
221 bool "Use 4kb/8kb for kernel stack instead of 8kb/16kb"
222 depends on PACK_STACK && !LOCKDEP
224 If you say Y here and the compiler supports the -mkernel-backchain
225 option the kernel will use a smaller kernel stack size. For 31 bit
226 the reduced size is 4kb instead of 8kb and for 64 bit it is 8kb
227 instead of 16kb. This allows to run more thread on a system and
228 reduces the pressure on the memory management for higher order
231 Say N if you are unsure.
235 bool "Detect kernel stack overflow"
237 This option enables the compiler option -mstack-guard and
238 -mstack-size if they are available. If the compiler supports them
239 it will emit additional code to each function prolog to trigger
240 an illegal operation if the kernel stack is about to overflow.
242 Say N if you are unsure.
245 int "Size of the guard area (128-1024)"
247 depends on CHECK_STACK
250 This allows you to specify the size of the guard area at the lower
251 end of the kernel stack. If the kernel stack points into the guard
252 area on function entry an illegal operation is triggered. The size
253 needs to be a power of 2. Please keep in mind that the size of an
254 interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
255 The minimum size for the stack guard should be 256 for 31 bit and
259 bool "Emit compiler warnings for function with broken stack usage"
261 This option enables the compiler options -mwarn-framesize and
262 -mwarn-dynamicstack. If the compiler supports these options it
263 will generate warnings for function which either use alloca or
264 create a stack frame bigger then CONFIG_WARN_STACK_SIZE.
266 Say N if you are unsure.
268 config WARN_STACK_SIZE
269 int "Maximum frame size considered safe (128-2048)"
271 depends on WARN_STACK
274 This allows you to specify the maximum frame size a function may
275 have without the compiler complaining about it.
277 config ARCH_POPULATES_NODE_MAP
280 comment "Kernel preemption"
282 source "kernel/Kconfig.preempt"
286 comment "I/O subsystem configuration"
288 config MACHCHK_WARNING
289 bool "Process warning machine checks"
291 Select this option if you want the machine check handler on IBM S/390 or
292 zSeries to process warning machine checks (e.g. on power failures).
296 tristate "QDIO support"
298 This driver provides the Queued Direct I/O base support for
301 For details please refer to the documentation provided by IBM at
302 <http://www10.software.ibm.com/developerworks/opensource/linux390>
304 To compile this driver as a module, choose M here: the
305 module will be called qdio.
310 bool "Extended debugging information"
313 Say Y here to get extended debugging output in
314 /sys/kernel/debug/s390dbf/qdio...
315 Warning: this option reduces the performance of the QDIO module.
322 bool "Builtin IPL record support"
324 If you want to use the produced kernel to IPL directly from a
325 device, you have to merge a bootsector specific to the device
326 into the first bytes of the kernel. You will have to select the
330 prompt "IPL method generated into head.S"
334 Select "tape" if you want to IPL the image from a Tape.
336 Select "vm_reader" if you are running under VM/ESA and want
337 to IPL the image from the emulated card reader.
347 source "fs/Kconfig.binfmt"
350 bool "Show crashed user process info"
352 Say Y to print all process fault locations to the console. This is
353 a debugging option; you probably do not want to set it unless you
354 are an S390 port maintainer.
357 bool "Pseudo page fault support"
359 Select this option, if you want to use PFAULT pseudo page fault
360 handling under VM. If running native or in LPAR, this option
361 has no effect. If your VM does not support PFAULT, PAGEEX
362 pseudo page fault handling will be used.
363 Note that VM 4.2 supports PFAULT but has a bug in its
364 implementation that causes some problems.
365 Everybody who wants to run Linux under VM != VM4.2 should select
369 bool "VM shared kernel support"
371 Select this option, if you want to share the text segment of the
372 Linux kernel between different VM guests. This reduces memory
373 usage with lots of guests but greatly increases kernel size.
374 Also if a kernel was IPL'ed from a shared segment the kexec system
376 You should only select this option if you know what you are
377 doing and want to exploit this feature.
380 tristate "Cooperative memory management"
382 Select this option, if you want to enable the kernel interface
383 to reduce the memory size of the system. This is accomplished
384 by allocating pages of memory and put them "on hold". This only
385 makes sense for a system running under VM where the unused pages
386 will be reused by VM for other guest systems. The interface
387 allows an external monitor to balance memory of many systems.
388 Everybody who wants to run Linux under VM should select this
392 bool "/proc interface to cooperative memory management"
395 Select this option to enable the /proc interface to the
396 cooperative memory management.
399 bool "IUCV special message interface to cooperative memory management"
400 depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
402 Select this option to enable the special message interface to
403 the cooperative memory management.
406 bool "Virtual CPU timer support"
408 This provides a kernel interface for virtual CPU timers.
411 config VIRT_CPU_ACCOUNTING
412 bool "Base user process accounting on virtual cpu timer"
413 depends on VIRT_TIMER
415 Select this option to use CPU timer deltas to do user
419 bool "Linux - VM Monitor Stream, base infrastructure"
420 depends on PROC_FS && VIRT_TIMER=y
422 This provides a kernel interface for creating and updating z/VM APPLDATA
423 monitor records. The monitor records are updated at certain time
424 intervals, once the timer is started.
425 Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
426 i.e. enables or disables monitoring on the Linux side.
427 A custom interval value (in seconds) can be written to
428 /proc/appldata/interval.
430 Defaults are 60 seconds interval and timer off.
431 The /proc entries can also be read from, showing the current settings.
434 tristate "Monitor memory management statistics"
435 depends on APPLDATA_BASE && VM_EVENT_COUNTERS
437 This provides memory management related data to the Linux - VM Monitor
438 Stream, like paging/swapping rate, memory utilisation, etc.
439 Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
440 APPLDATA monitor record, i.e. enables or disables monitoring this record
444 The /proc entry can also be read from, showing the current settings.
446 This can also be compiled as a module, which will be called
450 tristate "Monitor OS statistics"
451 depends on APPLDATA_BASE
453 This provides OS related data to the Linux - VM Monitor Stream, like
454 CPU utilisation, etc.
455 Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
456 APPLDATA monitor record, i.e. enables or disables monitoring this record
460 This can also be compiled as a module, which will be called
463 config APPLDATA_NET_SUM
464 tristate "Monitor overall network statistics"
465 depends on APPLDATA_BASE
467 This provides network related data to the Linux - VM Monitor Stream,
468 currently there is only a total sum of network I/O statistics, no
470 Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
471 APPLDATA monitor record, i.e. enables or disables monitoring this record
475 This can also be compiled as a module, which will be called
478 source kernel/Kconfig.hz
481 bool "No HZ timer ticks in idle"
483 Switches the regular HZ timer off when the system is going idle.
484 This helps z/VM to detect that the Linux system is idle. VM can
485 then "swap-out" this guest which reduces memory usage. It also
486 reduces the overhead of idle systems.
488 The HZ timer can be switched on/off via /proc/sys/kernel/hz_timer.
489 hz_timer=0 means HZ timer is disabled. hz_timer=1 means HZ
492 config NO_IDLE_HZ_INIT
493 bool "HZ timer in idle off by default"
494 depends on NO_IDLE_HZ
496 The HZ timer is switched off in idle by default. That means the
497 HZ timer is already disabled at boot time.
500 bool "s390 hypervisor file system support"
501 select SYS_HYPERVISOR
504 This is a virtual file system intended to provide accounting
505 information in an s390 hypervisor environment.
508 bool "kexec system call"
510 kexec is a system call that implements the ability to shutdown your
511 current kernel, and to start another kernel. It is like a reboot
512 but is independent of hardware/microcode support.
515 tristate "zfcpdump support"
519 Select this option if you want to build an zfcpdump enabled kernel.
520 Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
532 source "drivers/Kconfig"
536 source "arch/s390/Kconfig.debug"
538 source "security/Kconfig"
540 source "crypto/Kconfig"