2 # For a description of the syntax of this configuration file,
3 # see Documentation/kbuild/kconfig-language.txt.
10 config LOCKDEP_SUPPORT
14 config STACKTRACE_SUPPORT
18 config RWSEM_GENERIC_SPINLOCK
21 config RWSEM_XCHGADD_ALGORITHM
25 config ARCH_HAS_ILOG2_U32
29 config ARCH_HAS_ILOG2_U64
33 config GENERIC_HWEIGHT
37 config GENERIC_CALIBRATE_DELAY
44 mainmenu "Linux Kernel Configuration"
54 comment "Processor type and features"
59 Select this option if you have a 64 bit IBM zSeries machine
60 and want to use the 64 bit addressing mode.
67 bool "Symmetric multi-processing support"
69 This enables support for systems with more than one CPU. If you have
70 a system with only one CPU, like most personal computers, say N. If
71 you have a system with more than one CPU, say Y.
73 If you say N here, the kernel will run on single and multiprocessor
74 machines, but will use only one CPU of a multiprocessor machine. If
75 you say Y here, the kernel will run on many, but not all,
76 singleprocessor machines. On a singleprocessor machine, the kernel
77 will run faster if you say N here.
79 See also the <file:Documentation/smp.txt> and the SMP-HOWTO
80 available at <http://www.tldp.org/docs.html#howto>.
82 Even if you don't know what to do here, say Y.
85 int "Maximum number of CPUs (2-64)"
90 This allows you to specify the maximum number of CPUs which this
91 kernel will support. The maximum supported value is 64 and the
92 minimum value which makes sense is 2.
94 This is purely to save memory - each supported CPU adds
95 approximately sixteen kilobytes to the kernel image.
98 bool "Support for hot-pluggable CPUs"
103 Say Y here to be able to turn CPUs off and on. CPUs
104 can be controlled through /sys/devices/system/cpu/cpu#.
105 Say N if you want to disable CPU hotplug.
107 config DEFAULT_MIGRATION_COST
112 bool "IEEE FPU emulation"
115 This option is required for IEEE compliant floating point arithmetic
116 on older S/390 machines. Say Y unless you know your machine doesn't
120 bool "Kernel support for 31 bit emulation"
123 Select this option if you want to enable your system kernel to
124 handle system-calls from ELF binaries for 31 bit ESA. This option
125 (and some other stuff like libraries and such) is needed for
126 executing 31 bit applications. It is safe to say "Y".
128 config SYSVIPC_COMPAT
130 depends on COMPAT && SYSVIPC
137 comment "Code generation options"
140 prompt "Processor type"
144 bool "S/390 model G5 and G6"
147 Select this to build a 31 bit kernel that works
148 on all S/390 and zSeries machines.
151 bool "IBM eServer zSeries model z800 and z900"
153 Select this to optimize for zSeries machines. This
154 will enable some optimizations that are not available
155 on older 31 bit only CPUs.
158 bool "IBM eServer zSeries model z890 and z990"
160 Select this enable optimizations for model z890/z990.
161 This will be slightly faster but does not work on
162 older machines such as the z900.
167 Select this to enable optimizations for IBM System z9-109, IBM
168 System z9 Enterprise Class (z9 EC), and IBM System z9 Business
169 Class (z9 BC). The kernel will be slightly faster but will not
170 work on older machines such as the z990, z890, z900, and z800.
175 bool "Pack kernel stack"
177 This option enables the compiler option -mkernel-backchain if it
178 is available. If the option is available the compiler supports
179 the new stack layout which dramatically reduces the minimum stack
180 frame size. With an old compiler a non-leaf function needs a
181 minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
182 -mkernel-backchain the minimum size drops to 16 byte on 31 bit
183 and 24 byte on 64 bit.
185 Say Y if you are unsure.
188 bool "Use 4kb/8kb for kernel stack instead of 8kb/16kb"
189 depends on PACK_STACK && !LOCKDEP
191 If you say Y here and the compiler supports the -mkernel-backchain
192 option the kernel will use a smaller kernel stack size. For 31 bit
193 the reduced size is 4kb instead of 8kb and for 64 bit it is 8kb
194 instead of 16kb. This allows to run more thread on a system and
195 reduces the pressure on the memory management for higher order
198 Say N if you are unsure.
202 bool "Detect kernel stack overflow"
204 This option enables the compiler option -mstack-guard and
205 -mstack-size if they are available. If the compiler supports them
206 it will emit additional code to each function prolog to trigger
207 an illegal operation if the kernel stack is about to overflow.
209 Say N if you are unsure.
212 int "Size of the guard area (128-1024)"
214 depends on CHECK_STACK
217 This allows you to specify the size of the guard area at the lower
218 end of the kernel stack. If the kernel stack points into the guard
219 area on function entry an illegal operation is triggered. The size
220 needs to be a power of 2. Please keep in mind that the size of an
221 interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
222 The minimum size for the stack guard should be 256 for 31 bit and
226 bool "Emit compiler warnings for function with broken stack usage"
228 This option enables the compiler options -mwarn-framesize and
229 -mwarn-dynamicstack. If the compiler supports these options it
230 will generate warnings for function which either use alloca or
231 create a stack frame bigger then CONFIG_WARN_STACK_SIZE.
233 Say N if you are unsure.
235 config WARN_STACK_SIZE
236 int "Maximum frame size considered safe (128-2048)"
238 depends on WARN_STACK
241 This allows you to specify the maximum frame size a function may
242 have without the compiler complaining about it.
246 comment "I/O subsystem configuration"
248 config MACHCHK_WARNING
249 bool "Process warning machine checks"
251 Select this option if you want the machine check handler on IBM S/390 or
252 zSeries to process warning machine checks (e.g. on power failures).
256 tristate "QDIO support"
258 This driver provides the Queued Direct I/O base support for
261 For details please refer to the documentation provided by IBM at
262 <http://www10.software.ibm.com/developerworks/opensource/linux390>
264 To compile this driver as a module, choose M here: the
265 module will be called qdio.
269 config QDIO_PERF_STATS
270 bool "Performance statistics in /proc"
273 Say Y here to get performance statistics in /proc/qdio_perf
278 bool "Extended debugging information"
281 Say Y here to get extended debugging output in
282 /sys/kernel/debug/s390dbf/qdio...
283 Warning: this option reduces the performance of the QDIO module.
290 bool "Preemptible Kernel"
292 This option reduces the latency of the kernel when reacting to
293 real-time or interactive events by allowing a low priority process to
294 be preempted even if it is in kernel mode executing a system call.
295 This allows applications to run more reliably even when the system is
298 Say N if you are unsure.
301 bool "Builtin IPL record support"
303 If you want to use the produced kernel to IPL directly from a
304 device, you have to merge a bootsector specific to the device
305 into the first bytes of the kernel. You will have to select the
309 prompt "IPL method generated into head.S"
313 Select "tape" if you want to IPL the image from a Tape.
315 Select "vm_reader" if you are running under VM/ESA and want
316 to IPL the image from the emulated card reader.
326 source "fs/Kconfig.binfmt"
329 bool "Show crashed user process info"
331 Say Y to print all process fault locations to the console. This is
332 a debugging option; you probably do not want to set it unless you
333 are an S390 port maintainer.
336 bool "Pseudo page fault support"
338 Select this option, if you want to use PFAULT pseudo page fault
339 handling under VM. If running native or in LPAR, this option
340 has no effect. If your VM does not support PFAULT, PAGEEX
341 pseudo page fault handling will be used.
342 Note that VM 4.2 supports PFAULT but has a bug in its
343 implementation that causes some problems.
344 Everybody who wants to run Linux under VM != VM4.2 should select
348 bool "VM shared kernel support"
350 Select this option, if you want to share the text segment of the
351 Linux kernel between different VM guests. This reduces memory
352 usage with lots of guests but greatly increases kernel size.
353 You should only select this option if you know what you are
354 doing and want to exploit this feature.
357 tristate "Cooperative memory management"
359 Select this option, if you want to enable the kernel interface
360 to reduce the memory size of the system. This is accomplished
361 by allocating pages of memory and put them "on hold". This only
362 makes sense for a system running under VM where the unused pages
363 will be reused by VM for other guest systems. The interface
364 allows an external monitor to balance memory of many systems.
365 Everybody who wants to run Linux under VM should select this
369 bool "/proc interface to cooperative memory management"
372 Select this option to enable the /proc interface to the
373 cooperative memory management.
376 bool "IUCV special message interface to cooperative memory management"
377 depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
379 Select this option to enable the special message interface to
380 the cooperative memory management.
383 bool "Virtual CPU timer support"
385 This provides a kernel interface for virtual CPU timers.
388 config VIRT_CPU_ACCOUNTING
389 bool "Base user process accounting on virtual cpu timer"
390 depends on VIRT_TIMER
392 Select this option to use CPU timer deltas to do user
396 bool "Linux - VM Monitor Stream, base infrastructure"
397 depends on PROC_FS && VIRT_TIMER=y
399 This provides a kernel interface for creating and updating z/VM APPLDATA
400 monitor records. The monitor records are updated at certain time
401 intervals, once the timer is started.
402 Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
403 i.e. enables or disables monitoring on the Linux side.
404 A custom interval value (in seconds) can be written to
405 /proc/appldata/interval.
407 Defaults are 60 seconds interval and timer off.
408 The /proc entries can also be read from, showing the current settings.
411 tristate "Monitor memory management statistics"
412 depends on APPLDATA_BASE
414 This provides memory management related data to the Linux - VM Monitor
415 Stream, like paging/swapping rate, memory utilisation, etc.
416 Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
417 APPLDATA monitor record, i.e. enables or disables monitoring this record
421 The /proc entry can also be read from, showing the current settings.
423 This can also be compiled as a module, which will be called
427 tristate "Monitor OS statistics"
428 depends on APPLDATA_BASE
430 This provides OS related data to the Linux - VM Monitor Stream, like
431 CPU utilisation, etc.
432 Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
433 APPLDATA monitor record, i.e. enables or disables monitoring this record
437 This can also be compiled as a module, which will be called
440 config APPLDATA_NET_SUM
441 tristate "Monitor overall network statistics"
442 depends on APPLDATA_BASE
444 This provides network related data to the Linux - VM Monitor Stream,
445 currently there is only a total sum of network I/O statistics, no
447 Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
448 APPLDATA monitor record, i.e. enables or disables monitoring this record
452 This can also be compiled as a module, which will be called
456 bool "No HZ timer ticks in idle"
458 Switches the regular HZ timer off when the system is going idle.
459 This helps z/VM to detect that the Linux system is idle. VM can
460 then "swap-out" this guest which reduces memory usage. It also
461 reduces the overhead of idle systems.
463 The HZ timer can be switched on/off via /proc/sys/kernel/hz_timer.
464 hz_timer=0 means HZ timer is disabled. hz_timer=1 means HZ
467 config NO_IDLE_HZ_INIT
468 bool "HZ timer in idle off by default"
469 depends on NO_IDLE_HZ
471 The HZ timer is switched off in idle by default. That means the
472 HZ timer is already disabled at boot time.
475 bool "s390 hypervisor file system support"
476 select SYS_HYPERVISOR
479 This is a virtual file system intended to provide accounting
480 information in an s390 hypervisor environment.
483 bool "kexec system call"
485 kexec is a system call that implements the ability to shutdown your
486 current kernel, and to start another kernel. It is like a reboot
487 but is independent of hardware/microcode support.
497 source "drivers/base/Kconfig"
499 source "drivers/connector/Kconfig"
501 source "drivers/scsi/Kconfig"
503 source "drivers/s390/Kconfig"
505 source "drivers/net/Kconfig"
509 menu "Instrumentation Support"
511 source "arch/s390/oprofile/Kconfig"
514 bool "Kprobes (EXPERIMENTAL)"
515 depends on EXPERIMENTAL && MODULES
517 Kprobes allows you to trap at almost any kernel address and
518 execute a callback function. register_kprobe() establishes
519 a probepoint and specifies the callback. Kprobes is useful
520 for kernel debugging, non-intrusive instrumentation and testing.
521 If in doubt, say "N".
525 source "arch/s390/Kconfig.debug"
527 source "security/Kconfig"
529 source "crypto/Kconfig"