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 GENERIC_HWEIGHT
29 config GENERIC_CALIBRATE_DELAY
36 mainmenu "Linux Kernel Configuration"
46 comment "Processor type and features"
51 Select this option if you have a 64 bit IBM zSeries machine
52 and want to use the 64 bit addressing mode.
59 bool "Symmetric multi-processing support"
61 This enables support for systems with more than one CPU. If you have
62 a system with only one CPU, like most personal computers, say N. If
63 you have a system with more than one CPU, say Y.
65 If you say N here, the kernel will run on single and multiprocessor
66 machines, but will use only one CPU of a multiprocessor machine. If
67 you say Y here, the kernel will run on many, but not all,
68 singleprocessor machines. On a singleprocessor machine, the kernel
69 will run faster if you say N here.
71 See also the <file:Documentation/smp.txt> and the SMP-HOWTO
72 available at <http://www.tldp.org/docs.html#howto>.
74 Even if you don't know what to do here, say Y.
77 int "Maximum number of CPUs (2-64)"
82 This allows you to specify the maximum number of CPUs which this
83 kernel will support. The maximum supported value is 64 and the
84 minimum value which makes sense is 2.
86 This is purely to save memory - each supported CPU adds
87 approximately sixteen kilobytes to the kernel image.
90 bool "Support for hot-pluggable CPUs"
95 Say Y here to be able to turn CPUs off and on. CPUs
96 can be controlled through /sys/devices/system/cpu/cpu#.
97 Say N if you want to disable CPU hotplug.
99 config DEFAULT_MIGRATION_COST
104 bool "IEEE FPU emulation"
107 This option is required for IEEE compliant floating point arithmetic
108 on older S/390 machines. Say Y unless you know your machine doesn't
112 bool "Kernel support for 31 bit emulation"
115 Select this option if you want to enable your system kernel to
116 handle system-calls from ELF binaries for 31 bit ESA. This option
117 (and some other stuff like libraries and such) is needed for
118 executing 31 bit applications. It is safe to say "Y".
120 config SYSVIPC_COMPAT
122 depends on COMPAT && SYSVIPC
129 comment "Code generation options"
132 prompt "Processor type"
136 bool "S/390 model G5 and G6"
139 Select this to build a 31 bit kernel that works
140 on all S/390 and zSeries machines.
143 bool "IBM eServer zSeries model z800 and z900"
145 Select this to optimize for zSeries machines. This
146 will enable some optimizations that are not available
147 on older 31 bit only CPUs.
150 bool "IBM eServer zSeries model z890 and z990"
152 Select this enable optimizations for model z890/z990.
153 This will be slightly faster but does not work on
154 older machines such as the z900.
159 Select this to enable optimizations for IBM System z9-109, IBM
160 System z9 Enterprise Class (z9 EC), and IBM System z9 Business
161 Class (z9 BC). The kernel will be slightly faster but will not
162 work on older machines such as the z990, z890, z900, and z800.
167 bool "Pack kernel stack"
169 This option enables the compiler option -mkernel-backchain if it
170 is available. If the option is available the compiler supports
171 the new stack layout which dramatically reduces the minimum stack
172 frame size. With an old compiler a non-leaf function needs a
173 minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
174 -mkernel-backchain the minimum size drops to 16 byte on 31 bit
175 and 24 byte on 64 bit.
177 Say Y if you are unsure.
180 bool "Use 4kb/8kb for kernel stack instead of 8kb/16kb"
181 depends on PACK_STACK && !LOCKDEP
183 If you say Y here and the compiler supports the -mkernel-backchain
184 option the kernel will use a smaller kernel stack size. For 31 bit
185 the reduced size is 4kb instead of 8kb and for 64 bit it is 8kb
186 instead of 16kb. This allows to run more thread on a system and
187 reduces the pressure on the memory management for higher order
190 Say N if you are unsure.
194 bool "Detect kernel stack overflow"
196 This option enables the compiler option -mstack-guard and
197 -mstack-size if they are available. If the compiler supports them
198 it will emit additional code to each function prolog to trigger
199 an illegal operation if the kernel stack is about to overflow.
201 Say N if you are unsure.
204 int "Size of the guard area (128-1024)"
206 depends on CHECK_STACK
209 This allows you to specify the size of the guard area at the lower
210 end of the kernel stack. If the kernel stack points into the guard
211 area on function entry an illegal operation is triggered. The size
212 needs to be a power of 2. Please keep in mind that the size of an
213 interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
214 The minimum size for the stack guard should be 256 for 31 bit and
218 bool "Emit compiler warnings for function with broken stack usage"
220 This option enables the compiler options -mwarn-framesize and
221 -mwarn-dynamicstack. If the compiler supports these options it
222 will generate warnings for function which either use alloca or
223 create a stack frame bigger then CONFIG_WARN_STACK_SIZE.
225 Say N if you are unsure.
227 config WARN_STACK_SIZE
228 int "Maximum frame size considered safe (128-2048)"
230 depends on WARN_STACK
233 This allows you to specify the maximum frame size a function may
234 have without the compiler complaining about it.
241 comment "I/O subsystem configuration"
243 config MACHCHK_WARNING
244 bool "Process warning machine checks"
246 Select this option if you want the machine check handler on IBM S/390 or
247 zSeries to process warning machine checks (e.g. on power failures).
251 tristate "QDIO support"
253 This driver provides the Queued Direct I/O base support for
256 For details please refer to the documentation provided by IBM at
257 <http://www10.software.ibm.com/developerworks/opensource/linux390>
259 To compile this driver as a module, choose M here: the
260 module will be called qdio.
265 bool "Extended debugging information"
268 Say Y here to get extended debugging output in
269 /sys/kernel/debug/s390dbf/qdio...
270 Warning: this option reduces the performance of the QDIO module.
277 bool "Preemptible Kernel"
279 This option reduces the latency of the kernel when reacting to
280 real-time or interactive events by allowing a low priority process to
281 be preempted even if it is in kernel mode executing a system call.
282 This allows applications to run more reliably even when the system is
285 Say N if you are unsure.
288 bool "Builtin IPL record support"
290 If you want to use the produced kernel to IPL directly from a
291 device, you have to merge a bootsector specific to the device
292 into the first bytes of the kernel. You will have to select the
296 prompt "IPL method generated into head.S"
300 Select "tape" if you want to IPL the image from a Tape.
302 Select "vm_reader" if you are running under VM/ESA and want
303 to IPL the image from the emulated card reader.
313 source "fs/Kconfig.binfmt"
316 bool "Show crashed user process info"
318 Say Y to print all process fault locations to the console. This is
319 a debugging option; you probably do not want to set it unless you
320 are an S390 port maintainer.
323 bool "Pseudo page fault support"
325 Select this option, if you want to use PFAULT pseudo page fault
326 handling under VM. If running native or in LPAR, this option
327 has no effect. If your VM does not support PFAULT, PAGEEX
328 pseudo page fault handling will be used.
329 Note that VM 4.2 supports PFAULT but has a bug in its
330 implementation that causes some problems.
331 Everybody who wants to run Linux under VM != VM4.2 should select
335 bool "VM shared kernel support"
337 Select this option, if you want to share the text segment of the
338 Linux kernel between different VM guests. This reduces memory
339 usage with lots of guests but greatly increases kernel size.
340 You should only select this option if you know what you are
341 doing and want to exploit this feature.
344 tristate "Cooperative memory management"
346 Select this option, if you want to enable the kernel interface
347 to reduce the memory size of the system. This is accomplished
348 by allocating pages of memory and put them "on hold". This only
349 makes sense for a system running under VM where the unused pages
350 will be reused by VM for other guest systems. The interface
351 allows an external monitor to balance memory of many systems.
352 Everybody who wants to run Linux under VM should select this
356 bool "/proc interface to cooperative memory management"
359 Select this option to enable the /proc interface to the
360 cooperative memory management.
363 bool "IUCV special message interface to cooperative memory management"
364 depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
366 Select this option to enable the special message interface to
367 the cooperative memory management.
370 bool "Virtual CPU timer support"
372 This provides a kernel interface for virtual CPU timers.
375 config VIRT_CPU_ACCOUNTING
376 bool "Base user process accounting on virtual cpu timer"
377 depends on VIRT_TIMER
379 Select this option to use CPU timer deltas to do user
383 bool "Linux - VM Monitor Stream, base infrastructure"
384 depends on PROC_FS && VIRT_TIMER=y
386 This provides a kernel interface for creating and updating z/VM APPLDATA
387 monitor records. The monitor records are updated at certain time
388 intervals, once the timer is started.
389 Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
390 i.e. enables or disables monitoring on the Linux side.
391 A custom interval value (in seconds) can be written to
392 /proc/appldata/interval.
394 Defaults are 60 seconds interval and timer off.
395 The /proc entries can also be read from, showing the current settings.
398 tristate "Monitor memory management statistics"
399 depends on APPLDATA_BASE
401 This provides memory management related data to the Linux - VM Monitor
402 Stream, like paging/swapping rate, memory utilisation, etc.
403 Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
404 APPLDATA monitor record, i.e. enables or disables monitoring this record
408 The /proc entry can also be read from, showing the current settings.
410 This can also be compiled as a module, which will be called
414 tristate "Monitor OS statistics"
415 depends on APPLDATA_BASE
417 This provides OS related data to the Linux - VM Monitor Stream, like
418 CPU utilisation, etc.
419 Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
420 APPLDATA monitor record, i.e. enables or disables monitoring this record
424 This can also be compiled as a module, which will be called
427 config APPLDATA_NET_SUM
428 tristate "Monitor overall network statistics"
429 depends on APPLDATA_BASE
431 This provides network related data to the Linux - VM Monitor Stream,
432 currently there is only a total sum of network I/O statistics, no
434 Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
435 APPLDATA monitor record, i.e. enables or disables monitoring this record
439 This can also be compiled as a module, which will be called
443 bool "No HZ timer ticks in idle"
445 Switches the regular HZ timer off when the system is going idle.
446 This helps z/VM to detect that the Linux system is idle. VM can
447 then "swap-out" this guest which reduces memory usage. It also
448 reduces the overhead of idle systems.
450 The HZ timer can be switched on/off via /proc/sys/kernel/hz_timer.
451 hz_timer=0 means HZ timer is disabled. hz_timer=1 means HZ
454 config NO_IDLE_HZ_INIT
455 bool "HZ timer in idle off by default"
456 depends on NO_IDLE_HZ
458 The HZ timer is switched off in idle by default. That means the
459 HZ timer is already disabled at boot time.
462 bool "s390 hypervisor file system support"
463 select SYS_HYPERVISOR
466 This is a virtual file system intended to provide accounting
467 information in an s390 hypervisor environment.
470 bool "kexec system call"
472 kexec is a system call that implements the ability to shutdown your
473 current kernel, and to start another kernel. It is like a reboot
474 but is independent of hardware/microcode support.
484 source "drivers/base/Kconfig"
486 source "drivers/connector/Kconfig"
488 source "drivers/scsi/Kconfig"
490 source "drivers/s390/Kconfig"
492 source "drivers/net/Kconfig"
496 menu "Instrumentation Support"
498 source "arch/s390/oprofile/Kconfig"
501 bool "Kprobes (EXPERIMENTAL)"
502 depends on EXPERIMENTAL && MODULES
504 Kprobes allows you to trap at almost any kernel address and
505 execute a callback function. register_kprobe() establishes
506 a probepoint and specifies the callback. Kprobes is useful
507 for kernel debugging, non-intrusive instrumentation and testing.
508 If in doubt, say "N".
512 source "arch/s390/Kconfig.debug"
514 source "security/Kconfig"
516 source "crypto/Kconfig"