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 mainmenu "Linux Kernel Configuration"
61 comment "Processor type and features"
66 Select this option if you have a 64 bit IBM zSeries machine
67 and want to use the 64 bit addressing mode.
74 bool "Symmetric multi-processing support"
76 This enables support for systems with more than one CPU. If you have
77 a system with only one CPU, like most personal computers, say N. If
78 you have a system with more than one CPU, say Y.
80 If you say N here, the kernel will run on single and multiprocessor
81 machines, but will use only one CPU of a multiprocessor machine. If
82 you say Y here, the kernel will run on many, but not all,
83 singleprocessor machines. On a singleprocessor machine, the kernel
84 will run faster if you say N here.
86 See also the SMP-HOWTO available at
87 <http://www.tldp.org/docs.html#howto>.
89 Even if you don't know what to do here, say Y.
92 int "Maximum number of CPUs (2-64)"
97 This allows you to specify the maximum number of CPUs which this
98 kernel will support. The maximum supported value is 64 and the
99 minimum value which makes sense is 2.
101 This is purely to save memory - each supported CPU adds
102 approximately sixteen kilobytes to the kernel image.
105 bool "Support for hot-pluggable CPUs"
110 Say Y here to be able to turn CPUs off and on. CPUs
111 can be controlled through /sys/devices/system/cpu/cpu#.
112 Say N if you want to disable CPU hotplug.
115 bool "IEEE FPU emulation"
118 This option is required for IEEE compliant floating point arithmetic
119 on older S/390 machines. Say Y unless you know your machine doesn't
123 bool "Kernel support for 31 bit emulation"
126 Select this option if you want to enable your system kernel to
127 handle system-calls from ELF binaries for 31 bit ESA. This option
128 (and some other stuff like libraries and such) is needed for
129 executing 31 bit applications. It is safe to say "Y".
131 config SYSVIPC_COMPAT
133 depends on COMPAT && SYSVIPC
140 config S390_SWITCH_AMODE
141 bool "Switch kernel/user addressing modes"
143 This option allows to switch the addressing modes of kernel and user
144 space. The kernel parameter switch_amode=on will enable this feature,
145 default is disabled. Enabling this (via kernel parameter) on machines
146 earlier than IBM System z9-109 EC/BC will reduce system performance.
148 Note that this option will also be selected by selecting the execute
149 protection option below. Enabling the execute protection via the
150 noexec kernel parameter will also switch the addressing modes,
151 independent of the switch_amode kernel parameter.
154 config S390_EXEC_PROTECT
155 bool "Data execute protection"
156 select S390_SWITCH_AMODE
158 This option allows to enable a buffer overflow protection for user
159 space programs and it also selects the addressing mode option above.
160 The kernel parameter noexec=on will enable this feature and also
161 switch the addressing modes, default is disabled. Enabling this (via
162 kernel parameter) on machines earlier than IBM System z9-109 EC/BC
163 will reduce system performance.
165 comment "Code generation options"
168 prompt "Processor type"
172 bool "S/390 model G5 and G6"
175 Select this to build a 31 bit kernel that works
176 on all S/390 and zSeries machines.
179 bool "IBM eServer zSeries model z800 and z900"
181 Select this to optimize for zSeries machines. This
182 will enable some optimizations that are not available
183 on older 31 bit only CPUs.
186 bool "IBM eServer zSeries model z890 and z990"
188 Select this enable optimizations for model z890/z990.
189 This will be slightly faster but does not work on
190 older machines such as the z900.
195 Select this to enable optimizations for IBM System z9-109, IBM
196 System z9 Enterprise Class (z9 EC), and IBM System z9 Business
197 Class (z9 BC). The kernel will be slightly faster but will not
198 work on older machines such as the z990, z890, z900, and z800.
203 bool "Pack kernel stack"
205 This option enables the compiler option -mkernel-backchain if it
206 is available. If the option is available the compiler supports
207 the new stack layout which dramatically reduces the minimum stack
208 frame size. With an old compiler a non-leaf function needs a
209 minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
210 -mkernel-backchain the minimum size drops to 16 byte on 31 bit
211 and 24 byte on 64 bit.
213 Say Y if you are unsure.
216 bool "Use 4kb/8kb for kernel stack instead of 8kb/16kb"
217 depends on PACK_STACK && !LOCKDEP
219 If you say Y here and the compiler supports the -mkernel-backchain
220 option the kernel will use a smaller kernel stack size. For 31 bit
221 the reduced size is 4kb instead of 8kb and for 64 bit it is 8kb
222 instead of 16kb. This allows to run more thread on a system and
223 reduces the pressure on the memory management for higher order
226 Say N if you are unsure.
230 bool "Detect kernel stack overflow"
232 This option enables the compiler option -mstack-guard and
233 -mstack-size if they are available. If the compiler supports them
234 it will emit additional code to each function prolog to trigger
235 an illegal operation if the kernel stack is about to overflow.
237 Say N if you are unsure.
240 int "Size of the guard area (128-1024)"
242 depends on CHECK_STACK
245 This allows you to specify the size of the guard area at the lower
246 end of the kernel stack. If the kernel stack points into the guard
247 area on function entry an illegal operation is triggered. The size
248 needs to be a power of 2. Please keep in mind that the size of an
249 interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
250 The minimum size for the stack guard should be 256 for 31 bit and
254 bool "Emit compiler warnings for function with broken stack usage"
256 This option enables the compiler options -mwarn-framesize and
257 -mwarn-dynamicstack. If the compiler supports these options it
258 will generate warnings for function which either use alloca or
259 create a stack frame bigger then CONFIG_WARN_STACK_SIZE.
261 Say N if you are unsure.
263 config WARN_STACK_SIZE
264 int "Maximum frame size considered safe (128-2048)"
266 depends on WARN_STACK
269 This allows you to specify the maximum frame size a function may
270 have without the compiler complaining about it.
272 config ARCH_POPULATES_NODE_MAP
275 comment "Kernel preemption"
277 source "kernel/Kconfig.preempt"
281 comment "I/O subsystem configuration"
283 config MACHCHK_WARNING
284 bool "Process warning machine checks"
286 Select this option if you want the machine check handler on IBM S/390 or
287 zSeries to process warning machine checks (e.g. on power failures).
291 tristate "QDIO support"
293 This driver provides the Queued Direct I/O base support for
296 For details please refer to the documentation provided by IBM at
297 <http://www10.software.ibm.com/developerworks/opensource/linux390>
299 To compile this driver as a module, choose M here: the
300 module will be called qdio.
305 bool "Extended debugging information"
308 Say Y here to get extended debugging output in
309 /sys/kernel/debug/s390dbf/qdio...
310 Warning: this option reduces the performance of the QDIO module.
317 bool "Builtin IPL record support"
319 If you want to use the produced kernel to IPL directly from a
320 device, you have to merge a bootsector specific to the device
321 into the first bytes of the kernel. You will have to select the
325 prompt "IPL method generated into head.S"
329 Select "tape" if you want to IPL the image from a Tape.
331 Select "vm_reader" if you are running under VM/ESA and want
332 to IPL the image from the emulated card reader.
342 source "fs/Kconfig.binfmt"
345 bool "Show crashed user process info"
347 Say Y to print all process fault locations to the console. This is
348 a debugging option; you probably do not want to set it unless you
349 are an S390 port maintainer.
352 bool "Pseudo page fault support"
354 Select this option, if you want to use PFAULT pseudo page fault
355 handling under VM. If running native or in LPAR, this option
356 has no effect. If your VM does not support PFAULT, PAGEEX
357 pseudo page fault handling will be used.
358 Note that VM 4.2 supports PFAULT but has a bug in its
359 implementation that causes some problems.
360 Everybody who wants to run Linux under VM != VM4.2 should select
364 bool "VM shared kernel support"
366 Select this option, if you want to share the text segment of the
367 Linux kernel between different VM guests. This reduces memory
368 usage with lots of guests but greatly increases kernel size.
369 Also if a kernel was IPL'ed from a shared segment the kexec system
371 You should only select this option if you know what you are
372 doing and want to exploit this feature.
375 tristate "Cooperative memory management"
377 Select this option, if you want to enable the kernel interface
378 to reduce the memory size of the system. This is accomplished
379 by allocating pages of memory and put them "on hold". This only
380 makes sense for a system running under VM where the unused pages
381 will be reused by VM for other guest systems. The interface
382 allows an external monitor to balance memory of many systems.
383 Everybody who wants to run Linux under VM should select this
387 bool "/proc interface to cooperative memory management"
390 Select this option to enable the /proc interface to the
391 cooperative memory management.
394 bool "IUCV special message interface to cooperative memory management"
395 depends on CMM && (SMSGIUCV=y || CMM=SMSGIUCV)
397 Select this option to enable the special message interface to
398 the cooperative memory management.
401 bool "Virtual CPU timer support"
403 This provides a kernel interface for virtual CPU timers.
406 config VIRT_CPU_ACCOUNTING
407 bool "Base user process accounting on virtual cpu timer"
408 depends on VIRT_TIMER
410 Select this option to use CPU timer deltas to do user
414 bool "Linux - VM Monitor Stream, base infrastructure"
415 depends on PROC_FS && VIRT_TIMER=y
417 This provides a kernel interface for creating and updating z/VM APPLDATA
418 monitor records. The monitor records are updated at certain time
419 intervals, once the timer is started.
420 Writing 1 or 0 to /proc/appldata/timer starts(1) or stops(0) the timer,
421 i.e. enables or disables monitoring on the Linux side.
422 A custom interval value (in seconds) can be written to
423 /proc/appldata/interval.
425 Defaults are 60 seconds interval and timer off.
426 The /proc entries can also be read from, showing the current settings.
429 tristate "Monitor memory management statistics"
430 depends on APPLDATA_BASE && VM_EVENT_COUNTERS
432 This provides memory management related data to the Linux - VM Monitor
433 Stream, like paging/swapping rate, memory utilisation, etc.
434 Writing 1 or 0 to /proc/appldata/memory creates(1) or removes(0) a z/VM
435 APPLDATA monitor record, i.e. enables or disables monitoring this record
439 The /proc entry can also be read from, showing the current settings.
441 This can also be compiled as a module, which will be called
445 tristate "Monitor OS statistics"
446 depends on APPLDATA_BASE
448 This provides OS related data to the Linux - VM Monitor Stream, like
449 CPU utilisation, etc.
450 Writing 1 or 0 to /proc/appldata/os creates(1) or removes(0) a z/VM
451 APPLDATA monitor record, i.e. enables or disables monitoring this record
455 This can also be compiled as a module, which will be called
458 config APPLDATA_NET_SUM
459 tristate "Monitor overall network statistics"
460 depends on APPLDATA_BASE
462 This provides network related data to the Linux - VM Monitor Stream,
463 currently there is only a total sum of network I/O statistics, no
465 Writing 1 or 0 to /proc/appldata/net_sum creates(1) or removes(0) a z/VM
466 APPLDATA monitor record, i.e. enables or disables monitoring this record
470 This can also be compiled as a module, which will be called
473 source kernel/Kconfig.hz
476 bool "No HZ timer ticks in idle"
478 Switches the regular HZ timer off when the system is going idle.
479 This helps z/VM to detect that the Linux system is idle. VM can
480 then "swap-out" this guest which reduces memory usage. It also
481 reduces the overhead of idle systems.
483 The HZ timer can be switched on/off via /proc/sys/kernel/hz_timer.
484 hz_timer=0 means HZ timer is disabled. hz_timer=1 means HZ
487 config NO_IDLE_HZ_INIT
488 bool "HZ timer in idle off by default"
489 depends on NO_IDLE_HZ
491 The HZ timer is switched off in idle by default. That means the
492 HZ timer is already disabled at boot time.
495 bool "s390 hypervisor file system support"
496 select SYS_HYPERVISOR
499 This is a virtual file system intended to provide accounting
500 information in an s390 hypervisor environment.
503 bool "kexec system call"
505 kexec is a system call that implements the ability to shutdown your
506 current kernel, and to start another kernel. It is like a reboot
507 but is independent of hardware/microcode support.
510 tristate "zfcpdump support"
514 Select this option if you want to build an zfcpdump enabled kernel.
515 Refer to <file:Documentation/s390/zfcpdump.txt> for more details on this.
527 source "drivers/Kconfig"
531 source "arch/s390/Kconfig.debug"
533 source "security/Kconfig"
535 source "crypto/Kconfig"