kconfig

linux 内核源代码

#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.txt.
#

config MMU
	def_bool y

config ZONE_DMA
	def_bool y
	depends on 64BIT

config LOCKDEP_SUPPORT
	def_bool y

config STACKTRACE_SUPPORT
	def_bool y

config RWSEM_GENERIC_SPINLOCK
	bool

config RWSEM_XCHGADD_ALGORITHM
	def_bool y

config ARCH_HAS_ILOG2_U32
	bool
	default n

config ARCH_HAS_ILOG2_U64
	bool
	default n

config GENERIC_HWEIGHT
	def_bool y

config GENERIC_TIME
	def_bool y

config GENERIC_BUG
	bool
	depends on BUG
	default y

config NO_IOMEM
	def_bool y

config NO_DMA
	def_bool y

mainmenu "Linux Kernel Configuration"

config S390
	def_bool y

source "init/Kconfig"

menu "Base setup"

comment "Processor type and features"

config 64BIT
	bool "64 bit kernel"
	help
	  Select this option if you have a 64 bit IBM zSeries machine
	  and want to use the 64 bit addressing mode.

config 32BIT
	bool
	default y if !64BIT

config SMP
	bool "Symmetric multi-processing support"
	---help---
	  This enables support for systems with more than one CPU. If you have
	  a system with only one CPU, like most personal computers, say N. If
	  you have a system with more than one CPU, say Y.

	  If you say N here, the kernel will run on single and multiprocessor
	  machines, but will use only one CPU of a multiprocessor machine. If
	  you say Y here, the kernel will run on many, but not all,
	  singleprocessor machines. On a singleprocessor machine, the kernel
	  will run faster if you say N here.

	  See also the <file:Documentation/smp.txt> and the SMP-HOWTO
	  available at <http://www.tldp.org/docs.html#howto>.

	  Even if you don't know what to do here, say Y.

config NR_CPUS
	int "Maximum number of CPUs (2-64)"
	range 2 64
	depends on SMP
	default "32"
	help
	  This allows you to specify the maximum number of CPUs which this
	  kernel will support.  The maximum supported value is 64 and the
	  minimum value which makes sense is 2.

	  This is purely to save memory - each supported CPU adds
	  approximately sixteen kilobytes to the kernel image.

config HOTPLUG_CPU
	bool "Support for hot-pluggable CPUs"
	depends on SMP
	select HOTPLUG
	default n
	help
	  Say Y here to be able to turn CPUs off and on. CPUs
	  can be controlled through /sys/devices/system/cpu/cpu#.
	  Say N if you want to disable CPU hotplug.

config MATHEMU
	bool "IEEE FPU emulation"
	depends on MARCH_G5
	help
	  This option is required for IEEE compliant floating point arithmetic
	  on older S/390 machines. Say Y unless you know your machine doesn't
	  need this.

config COMPAT
	bool "Kernel support for 31 bit emulation"
	depends on 64BIT
	help
	  Select this option if you want to enable your system kernel to
	  handle system-calls from ELF binaries for 31 bit ESA.  This option
	  (and some other stuff like libraries and such) is needed for
	  executing 31 bit applications.  It is safe to say "Y".

config SYSVIPC_COMPAT
	bool
	depends on COMPAT && SYSVIPC
	default y

config AUDIT_ARCH
	bool
	default y

config S390_SWITCH_AMODE
	bool "Switch kernel/user addressing modes"
	help
	  This option allows to switch the addressing modes of kernel and user
	  space. The kernel parameter switch_amode=on will enable this feature,
	  default is disabled. Enabling this (via kernel parameter) on machines
	  earlier than IBM System z9-109 EC/BC will reduce system performance.

	  Note that this option will also be selected by selecting the execute
	  protection option below. Enabling the execute protection via the
	  noexec kernel parameter will also switch the addressing modes,
	  independent of the switch_amode kernel parameter.


config S390_EXEC_PROTECT
	bool "Data execute protection"
	select S390_SWITCH_AMODE
	help
	  This option allows to enable a buffer overflow protection for user
	  space programs and it also selects the addressing mode option above.
	  The kernel parameter noexec=on will enable this feature and also
	  switch the addressing modes, default is disabled. Enabling this (via
	  kernel parameter) on machines earlier than IBM System z9-109 EC/BC
	  will reduce system performance.

comment "Code generation options"

choice
	prompt "Processor type"
	default MARCH_G5

config MARCH_G5
	bool "S/390 model G5 and G6"
	depends on !64BIT
	help
	  Select this to build a 31 bit kernel that works
	  on all S/390 and zSeries machines.

config MARCH_Z900
	bool "IBM eServer zSeries model z800 and z900"
	help
	  Select this to optimize for zSeries machines. This
	  will enable some optimizations that are not available
	  on older 31 bit only CPUs.

config MARCH_Z990
	bool "IBM eServer zSeries model z890 and z990"
	help
	  Select this enable optimizations for model z890/z990.
	  This will be slightly faster but does not work on
	  older machines such as the z900.

config MARCH_Z9_109
	bool "IBM System z9"
	help
	  Select this to enable optimizations for IBM System z9-109, IBM
	  System z9 Enterprise Class (z9 EC), and IBM System z9 Business
	  Class (z9 BC). The kernel will be slightly faster but will not
	  work on older machines such as the z990, z890, z900, and z800.

endchoice

config PACK_STACK
	bool "Pack kernel stack"
	help
	  This option enables the compiler option -mkernel-backchain if it
	  is available. If the option is available the compiler supports
	  the new stack layout which dramatically reduces the minimum stack
	  frame size. With an old compiler a non-leaf function needs a
	  minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With
	  -mkernel-backchain the minimum size drops to 16 byte on 31 bit
	  and 24 byte on 64 bit.

	  Say Y if you are unsure.

config SMALL_STACK
	bool "Use 4kb/8kb for kernel stack instead of 8kb/16kb"
	depends on PACK_STACK && !LOCKDEP
	help
	  If you say Y here and the compiler supports the -mkernel-backchain
	  option the kernel will use a smaller kernel stack size. For 31 bit
	  the reduced size is 4kb instead of 8kb and for 64 bit it is 8kb
	  instead of 16kb. This allows to run more thread on a system and
	  reduces the pressure on the memory management for higher order
	  page allocations.

	  Say N if you are unsure.


config CHECK_STACK
	bool "Detect kernel stack overflow"
	help
	  This option enables the compiler option -mstack-guard and
	  -mstack-size if they are available. If the compiler supports them
	  it will emit additional code to each function prolog to trigger
	  an illegal operation if the kernel stack is about to overflow.

	  Say N if you are unsure.

config STACK_GUARD
	int "Size of the guard area (128-1024)"
	range 128 1024
	depends on CHECK_STACK
	default "256"
	help
	  This allows you to specify the size of the guard area at the lower
	  end of the kernel stack. If the kernel stack points into the guard
	  area on function entry an illegal operation is triggered. The size
	  needs to be a power of 2. Please keep in mind that the size of an
	  interrupt frame is 184 bytes for 31 bit and 328 bytes on 64 bit.
	  The minimum size for the stack guard should be 256 for 31 bit and
	  512 for 64 bit.

config WARN_STACK
	bool "Emit compiler warnings for function with broken stack usage"
	help
	  This option enables the compiler options -mwarn-framesize and
	  -mwarn-dynamicstack. If the compiler supports these options it
	  will generate warnings for function which either use alloca or
	  create a stack frame bigger then CONFIG_WARN_STACK_SIZE.

	  Say N if you are unsure.

config WARN_STACK_SIZE
	int "Maximum frame size considered safe (128-2048)"
	range 128 2048
	depends on WARN_STACK
	default "256"
	help
	  This allows you to specify the maximum frame size a function may
	  have without the compiler complaining about it.

config ARCH_POPULATES_NODE_MAP
	def_bool y