+config ARCH
+ string
+ option env="ARCH"
+
+config KERNELVERSION
+ string
+ option env="KERNELVERSION"
+
config DEFCONFIG_LIST
string
depends on !UML
default "/lib/modules/$UNAME_RELEASE/.config"
default "/etc/kernel-config"
default "/boot/config-$UNAME_RELEASE"
+ default "$ARCH_DEFCONFIG"
default "arch/$ARCH/defconfig"
+config CONSTRUCTORS
+ bool
+ depends on !UML
+ default y
+
menu "General setup"
config EXPERIMENTAL
which is done within the script "scripts/setlocalversion".)
+config HAVE_KERNEL_GZIP
+ bool
+
+config HAVE_KERNEL_BZIP2
+ bool
+
+config HAVE_KERNEL_LZMA
+ bool
+
+config HAVE_KERNEL_LZO
+ bool
+
+choice
+ prompt "Kernel compression mode"
+ default KERNEL_GZIP
+ depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
+ help
+ The linux kernel is a kind of self-extracting executable.
+ Several compression algorithms are available, which differ
+ in efficiency, compression and decompression speed.
+ Compression speed is only relevant when building a kernel.
+ Decompression speed is relevant at each boot.
+
+ If you have any problems with bzip2 or lzma compressed
+ kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
+ version of this functionality (bzip2 only), for 2.4, was
+ supplied by Christian Ludwig)
+
+ High compression options are mostly useful for users, who
+ are low on disk space (embedded systems), but for whom ram
+ size matters less.
+
+ If in doubt, select 'gzip'
+
+config KERNEL_GZIP
+ bool "Gzip"
+ depends on HAVE_KERNEL_GZIP
+ help
+ The old and tried gzip compression. It provides a good balance
+ between compression ratio and decompression speed.
+
+config KERNEL_BZIP2
+ bool "Bzip2"
+ depends on HAVE_KERNEL_BZIP2
+ help
+ Its compression ratio and speed is intermediate.
+ Decompression speed is slowest among the three. The kernel
+ size is about 10% smaller with bzip2, in comparison to gzip.
+ Bzip2 uses a large amount of memory. For modern kernels you
+ will need at least 8MB RAM or more for booting.
+
+config KERNEL_LZMA
+ bool "LZMA"
+ depends on HAVE_KERNEL_LZMA
+ help
+ The most recent compression algorithm.
+ Its ratio is best, decompression speed is between the other
+ two. Compression is slowest. The kernel size is about 33%
+ smaller with LZMA in comparison to gzip.
+
+config KERNEL_LZO
+ bool "LZO"
+ depends on HAVE_KERNEL_LZO
+ help
+ Its compression ratio is the poorest among the 4. The kernel
+ size is about about 10% bigger than gzip; however its speed
+ (both compression and decompression) is the fastest.
+
+endchoice
+
config SWAP
bool "Support for paging of anonymous memory (swap)"
depends on MMU && BLOCK
If unsure, say Y.
+config POSIX_MQUEUE_SYSCTL
+ bool
+ depends on POSIX_MQUEUE
+ depends on SYSCTL
+ default y
+
config BSD_PROCESS_ACCT
bool "BSD Process Accounting"
help
process and it's parent. Note that this file format is incompatible
with previous v0/v1/v2 file formats, so you will need updated tools
for processing it. A preliminary version of these tools is available
- at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
+ at <http://www.gnu.org/software/acct/>.
config TASKSTATS
bool "Export task/process statistics through netlink (EXPERIMENTAL)"
Say N if unsure.
-config USER_NS
- bool "User Namespaces (EXPERIMENTAL)"
- default n
- depends on EXPERIMENTAL
- help
- Support user namespaces. This allows containers, i.e.
- vservers, to use user namespaces to provide different
- user info for different servers. If unsure, say N.
-
config AUDIT
bool "Auditing support"
depends on NET
config AUDITSYSCALL
bool "Enable system-call auditing support"
- depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
+ depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
default y if SECURITY_SELINUX
help
Enable low-overhead system-call auditing infrastructure that
config AUDIT_TREE
def_bool y
- depends on AUDITSYSCALL && INOTIFY
+ depends on AUDITSYSCALL
+ select INOTIFY
+
+menu "RCU Subsystem"
+
+choice
+ prompt "RCU Implementation"
+ default TREE_RCU
+
+config TREE_RCU
+ bool "Tree-based hierarchical RCU"
+ help
+ This option selects the RCU implementation that is
+ designed for very large SMP system with hundreds or
+ thousands of CPUs. It also scales down nicely to
+ smaller systems.
+
+config TREE_PREEMPT_RCU
+ bool "Preemptable tree-based hierarchical RCU"
+ depends on PREEMPT
+ help
+ This option selects the RCU implementation that is
+ designed for very large SMP systems with hundreds or
+ thousands of CPUs, but for which real-time response
+ is also required. It also scales down nicely to
+ smaller systems.
+
+config TINY_RCU
+ bool "UP-only small-memory-footprint RCU"
+ depends on !SMP
+ help
+ This option selects the RCU implementation that is
+ designed for UP systems from which real-time response
+ is not required. This option greatly reduces the
+ memory footprint of RCU.
+
+endchoice
+
+config RCU_TRACE
+ bool "Enable tracing for RCU"
+ depends on TREE_RCU || TREE_PREEMPT_RCU
+ help
+ This option provides tracing in RCU which presents stats
+ in debugfs for debugging RCU implementation.
+
+ Say Y here if you want to enable RCU tracing
+ Say N if you are unsure.
+
+config RCU_FANOUT
+ int "Tree-based hierarchical RCU fanout value"
+ range 2 64 if 64BIT
+ range 2 32 if !64BIT
+ depends on TREE_RCU || TREE_PREEMPT_RCU
+ default 64 if 64BIT
+ default 32 if !64BIT
+ help
+ This option controls the fanout of hierarchical implementations
+ of RCU, allowing RCU to work efficiently on machines with
+ large numbers of CPUs. This value must be at least the cube
+ root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
+ systems and up to 262,144 for 64-bit systems.
+
+ Select a specific number if testing RCU itself.
+ Take the default if unsure.
+
+config RCU_FANOUT_EXACT
+ bool "Disable tree-based hierarchical RCU auto-balancing"
+ depends on TREE_RCU || TREE_PREEMPT_RCU
+ default n
+ help
+ This option forces use of the exact RCU_FANOUT value specified,
+ regardless of imbalances in the hierarchy. This is useful for
+ testing RCU itself, and might one day be useful on systems with
+ strong NUMA behavior.
+
+ Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
+
+ Say N if unsure.
+
+config RCU_FAST_NO_HZ
+ bool "Accelerate last non-dyntick-idle CPU's grace periods"
+ depends on TREE_RCU && NO_HZ && SMP
+ default n
+ help
+ This option causes RCU to attempt to accelerate grace periods
+ in order to allow the final CPU to enter dynticks-idle state
+ more quickly. On the other hand, this option increases the
+ overhead of the dynticks-idle checking, particularly on systems
+ with large numbers of CPUs.
+
+ Say Y if energy efficiency is critically important, particularly
+ if you have relatively few CPUs.
+
+ Say N if you are unsure.
+
+config TREE_RCU_TRACE
+ def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
+ select DEBUG_FS
+ help
+ This option provides tracing for the TREE_RCU and
+ TREE_PREEMPT_RCU implementations, permitting Makefile to
+ trivially select kernel/rcutree_trace.c.
+
+endmenu # "RCU Subsystem"
config IKCONFIG
tristate "Kernel .config support"
config LOG_BUF_SHIFT
int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
range 12 21
- default 17 if S390 || LOCKDEP
- default 16 if X86_NUMAQ || IA64
- default 15 if SMP
- default 14
+ default 17
help
Select kernel log buffer size as a power of 2.
- Defaults and Examples:
- 17 => 128 KB for S/390
- 16 => 64 KB for x86 NUMAQ or IA-64
- 15 => 32 KB for SMP
- 14 => 16 KB for uniprocessor
+ Examples:
+ 17 => 128 KB
+ 16 => 64 KB
+ 15 => 32 KB
+ 14 => 16 KB
13 => 8 KB
12 => 4 KB
-config CGROUPS
- bool "Control Group support"
+#
+# Architectures with an unreliable sched_clock() should select this:
+#
+config HAVE_UNSTABLE_SCHED_CLOCK
+ bool
+
+menuconfig CGROUPS
+ boolean "Control Group support"
+ depends on EVENTFD
help
- This option will let you use process cgroup subsystems
- such as Cpusets
+ This option adds support for grouping sets of processes together, for
+ use with process control subsystems such as Cpusets, CFS, memory
+ controls or device isolation.
+ See
+ - Documentation/scheduler/sched-design-CFS.txt (CFS)
+ - Documentation/cgroups/ (features for grouping, isolation
+ and resource control)
Say N if unsure.
+if CGROUPS
+
config CGROUP_DEBUG
bool "Example debug cgroup subsystem"
depends on CGROUPS
+ default n
help
This option enables a simple cgroup subsystem that
exports useful debugging information about the cgroups
- framework
+ framework.
- Say N if unsure
+ Say N if unsure.
config CGROUP_NS
- bool "Namespace cgroup subsystem"
- depends on CGROUPS
- help
- Provides a simple namespace cgroup subsystem to
- provide hierarchical naming of sets of namespaces,
- for instance virtual servers and checkpoint/restart
- jobs.
+ bool "Namespace cgroup subsystem"
+ depends on CGROUPS
+ help
+ Provides a simple namespace cgroup subsystem to
+ provide hierarchical naming of sets of namespaces,
+ for instance virtual servers and checkpoint/restart
+ jobs.
-config CGROUP_CPUACCT
- bool "Simple CPU accounting cgroup subsystem"
+config CGROUP_FREEZER
+ bool "Freezer cgroup subsystem"
depends on CGROUPS
help
- Provides a simple Resource Controller for monitoring the
- total CPU consumed by the tasks in a cgroup
+ Provides a way to freeze and unfreeze all tasks in a
+ cgroup.
+
+config CGROUP_DEVICE
+ bool "Device controller for cgroups"
+ depends on CGROUPS && EXPERIMENTAL
+ help
+ Provides a cgroup implementing whitelists for devices which
+ a process in the cgroup can mknod or open.
config CPUSETS
bool "Cpuset support"
- depends on SMP && CGROUPS
+ depends on CGROUPS
help
This option will let you create and manage CPUSETs which
allow dynamically partitioning a system into sets of CPUs and
Say N if unsure.
-config FAIR_GROUP_SCHED
- bool "Fair group CPU scheduler"
+config PROC_PID_CPUSET
+ bool "Include legacy /proc/<pid>/cpuset file"
+ depends on CPUSETS
default y
+
+config CGROUP_CPUACCT
+ bool "Simple CPU accounting cgroup subsystem"
+ depends on CGROUPS
help
- This feature lets CPU scheduler recognize task groups and control CPU
- bandwidth allocation to such task groups.
+ Provides a simple Resource Controller for monitoring the
+ total CPU consumed by the tasks in a cgroup.
-choice
- depends on FAIR_GROUP_SCHED
- prompt "Basis for grouping tasks"
- default FAIR_USER_SCHED
-
-config FAIR_USER_SCHED
- bool "user id"
- help
- This option will choose userid as the basis for grouping
- tasks, thus providing equal CPU bandwidth to each user.
-
-config FAIR_CGROUP_SCHED
- bool "Control groups"
- depends on CGROUPS
- help
- This option allows you to create arbitrary task groups
- using the "cgroup" pseudo filesystem and control
- the cpu bandwidth allocated to each such task group.
- Refer to Documentation/cgroups.txt for more information
- on "cgroup" pseudo filesystem.
+config RESOURCE_COUNTERS
+ bool "Resource counters"
+ help
+ This option enables controller independent resource accounting
+ infrastructure that works with cgroups.
+ depends on CGROUPS
-endchoice
+config CGROUP_MEM_RES_CTLR
+ bool "Memory Resource Controller for Control Groups"
+ depends on CGROUPS && RESOURCE_COUNTERS
+ select MM_OWNER
+ help
+ Provides a memory resource controller that manages both anonymous
+ memory and page cache. (See Documentation/cgroups/memory.txt)
+
+ Note that setting this option increases fixed memory overhead
+ associated with each page of memory in the system. By this,
+ 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
+ usage tracking struct at boot. Total amount of this is printed out
+ at boot.
+
+ Only enable when you're ok with these trade offs and really
+ sure you need the memory resource controller. Even when you enable
+ this, you can set "cgroup_disable=memory" at your boot option to
+ disable memory resource controller and you can avoid overheads.
+ (and lose benefits of memory resource controller)
+
+ This config option also selects MM_OWNER config option, which
+ could in turn add some fork/exit overhead.
+
+config CGROUP_MEM_RES_CTLR_SWAP
+ bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
+ depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
+ help
+ Add swap management feature to memory resource controller. When you
+ enable this, you can limit mem+swap usage per cgroup. In other words,
+ when you disable this, memory resource controller has no cares to
+ usage of swap...a process can exhaust all of the swap. This extension
+ is useful when you want to avoid exhaustion swap but this itself
+ adds more overheads and consumes memory for remembering information.
+ Especially if you use 32bit system or small memory system, please
+ be careful about enabling this. When memory resource controller
+ is disabled by boot option, this will be automatically disabled and
+ there will be no overhead from this. Even when you set this config=y,
+ if boot option "noswapaccount" is set, swap will not be accounted.
+ Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
+ size is 4096bytes, 512k per 1Gbytes of swap.
+
+menuconfig CGROUP_SCHED
+ bool "Group CPU scheduler"
+ depends on EXPERIMENTAL && CGROUPS
+ default n
+ help
+ This feature lets CPU scheduler recognize task groups and control CPU
+ bandwidth allocation to such task groups. It uses cgroups to group
+ tasks.
-config SYSFS_DEPRECATED
- bool "Create deprecated sysfs files"
- default y
+if CGROUP_SCHED
+config FAIR_GROUP_SCHED
+ bool "Group scheduling for SCHED_OTHER"
+ depends on CGROUP_SCHED
+ default CGROUP_SCHED
+
+config RT_GROUP_SCHED
+ bool "Group scheduling for SCHED_RR/FIFO"
+ depends on EXPERIMENTAL
+ depends on CGROUP_SCHED
+ default n
help
- This option creates deprecated symlinks such as the
- "device"-link, the <subsystem>:<name>-link, and the
- "bus"-link. It may also add deprecated key in the
- uevent environment.
- None of these features or values should be used today, as
- they export driver core implementation details to userspace
- or export properties which can't be kept stable across kernel
- releases.
+ This feature lets you explicitly allocate real CPU bandwidth
+ to users or control groups (depending on the "Basis for grouping tasks"
+ setting below. If enabled, it will also make it impossible to
+ schedule realtime tasks for non-root users until you allocate
+ realtime bandwidth for them.
+ See Documentation/scheduler/sched-rt-group.txt for more information.
- If enabled, this option will also move any device structures
- that belong to a class, back into the /sys/class hierarchy, in
- order to support older versions of udev.
+endif #CGROUP_SCHED
- If you are using a distro that was released in 2006 or later,
- it should be safe to say N here.
+endif # CGROUPS
-config PROC_PID_CPUSET
- bool "Include legacy /proc/<pid>/cpuset file"
- depends on CPUSETS
- default y
+config MM_OWNER
+ bool
+
+config SYSFS_DEPRECATED
+ bool
+
+config SYSFS_DEPRECATED_V2
+ bool "enable deprecated sysfs features to support old userspace tools"
+ depends on SYSFS
+ default n
+ select SYSFS_DEPRECATED
+ help
+ This option switches the layout of sysfs to the deprecated
+ version. Do not use it on recent distributions.
+
+ The current sysfs layout features a unified device tree at
+ /sys/devices/, which is able to express a hierarchy between
+ class devices. If the deprecated option is set to Y, the
+ unified device tree is split into a bus device tree at
+ /sys/devices/ and several individual class device trees at
+ /sys/class/. The class and bus devices will be connected by
+ "<subsystem>:<name>" and the "device" links. The "block"
+ class devices, will not show up in /sys/class/block/. Some
+ subsystems will suppress the creation of some devices which
+ depend on the unified device tree.
+
+ This option is not a pure compatibility option that can
+ be safely enabled on newer distributions. It will change the
+ layout of sysfs to the non-extensible deprecated version,
+ and disable some features, which can not be exported without
+ confusing older userspace tools. Since 2007/2008 all major
+ distributions do not enable this option, and ship no tools which
+ depend on the deprecated layout or this option.
+
+ If you are using a new kernel on an older distribution, or use
+ older userspace tools, you might need to say Y here. Do not say Y,
+ if the original kernel, that came with your distribution, has
+ this option set to N.
config RELAY
bool "Kernel->user space relay support (formerly relayfs)"
If unsure, say N.
+config NAMESPACES
+ bool "Namespaces support" if EMBEDDED
+ default !EMBEDDED
+ help
+ Provides the way to make tasks work with different objects using
+ the same id. For example same IPC id may refer to different objects
+ or same user id or pid may refer to different tasks when used in
+ different namespaces.
+
+config UTS_NS
+ bool "UTS namespace"
+ depends on NAMESPACES
+ help
+ In this namespace tasks see different info provided with the
+ uname() system call
+
+config IPC_NS
+ bool "IPC namespace"
+ depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
+ help
+ In this namespace tasks work with IPC ids which correspond to
+ different IPC objects in different namespaces.
+
+config USER_NS
+ bool "User namespace (EXPERIMENTAL)"
+ depends on NAMESPACES && EXPERIMENTAL
+ help
+ This allows containers, i.e. vservers, to use user namespaces
+ to provide different user info for different servers.
+ If unsure, say N.
+
+config PID_NS
+ bool "PID Namespaces (EXPERIMENTAL)"
+ default n
+ depends on NAMESPACES && EXPERIMENTAL
+ help
+ Support process id namespaces. This allows having multiple
+ processes with the same pid as long as they are in different
+ pid namespaces. This is a building block of containers.
+
+ Unless you want to work with an experimental feature
+ say N here.
+
+config NET_NS
+ bool "Network namespace"
+ default n
+ depends on NAMESPACES && EXPERIMENTAL && NET
+ help
+ Allow user space to create what appear to be multiple instances
+ of the network stack.
+
config BLK_DEV_INITRD
bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
depends on BROKEN || !FRV
endif
config CC_OPTIMIZE_FOR_SIZE
- bool "Optimize for size (Look out for broken compilers!)"
+ bool "Optimize for size"
default y
- depends on ARM || H8300 || SUPERH || EXPERIMENTAL
help
Enabling this option will pass "-Os" instead of "-O2" to gcc
resulting in a smaller kernel.
- WARNING: some versions of gcc may generate incorrect code with this
- option. If problems are observed, a gcc upgrade may be needed.
-
- If unsure, say N.
+ If unsure, say Y.
config SYSCTL
bool
+config ANON_INODES
+ bool
+
menuconfig EMBEDDED
bool "Configure standard kernel features (for small systems)"
help
config UID16
bool "Enable 16-bit UID system calls" if EMBEDDED
- depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
+ depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
default y
help
This enables the legacy 16-bit UID syscall wrappers.
config SYSCTL_SYSCALL
bool "Sysctl syscall support" if EMBEDDED
+ depends on PROC_SYSCTL
default y
select SYSCTL
---help---
help
Enable support for generating core dumps. Disabling saves about 4k.
+config PCSPKR_PLATFORM
+ bool "Enable PC-Speaker support" if EMBEDDED
+ depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
+ default y
+ help
+ This option allows to disable the internal PC-Speaker
+ support, saving some memory.
+
config BASE_FULL
default y
bool "Enable full-sized data structures for core" if EMBEDDED
support for "fast userspace mutexes". The resulting kernel may not
run glibc-based applications correctly.
-config ANON_INODES
- bool
-
config EPOLL
bool "Enable eventpoll support" if EMBEDDED
default y
config TIMERFD
bool "Enable timerfd() system call" if EMBEDDED
select ANON_INODES
- depends on BROKEN
default y
help
Enable the timerfd() system call that allows to receive timer
option replaces shmem and tmpfs with the much simpler ramfs code,
which may be appropriate on small systems without swap.
+config AIO
+ bool "Enable AIO support" if EMBEDDED
+ default y
+ help
+ This option enables POSIX asynchronous I/O which may by used
+ by some high performance threaded applications. Disabling
+ this option saves about 7k.
+
+config HAVE_PERF_EVENTS
+ bool
+ help
+ See tools/perf/design.txt for details.
+
+config PERF_USE_VMALLOC
+ bool
+ help
+ See tools/perf/design.txt for details
+
+menu "Kernel Performance Events And Counters"
+
+config PERF_EVENTS
+ bool "Kernel performance events and counters"
+ default y if (PROFILING || PERF_COUNTERS)
+ depends on HAVE_PERF_EVENTS
+ select ANON_INODES
+ help
+ Enable kernel support for various performance events provided
+ by software and hardware.
+
+ Software events are supported either built-in or via the
+ use of generic tracepoints.
+
+ Most modern CPUs support performance events via performance
+ counter registers. These registers count the number of certain
+ types of hw events: such as instructions executed, cachemisses
+ suffered, or branches mis-predicted - without slowing down the
+ kernel or applications. These registers can also trigger interrupts
+ when a threshold number of events have passed - and can thus be
+ used to profile the code that runs on that CPU.
+
+ The Linux Performance Event subsystem provides an abstraction of
+ these software and hardware event capabilities, available via a
+ system call and used by the "perf" utility in tools/perf/. It
+ provides per task and per CPU counters, and it provides event
+ capabilities on top of those.
+
+ Say Y if unsure.
+
+config PERF_COUNTERS
+ bool "Kernel performance counters (old config option)"
+ depends on HAVE_PERF_EVENTS
+ help
+ This config has been obsoleted by the PERF_EVENTS
+ config option - please see that one for details.
+
+ It has no effect on the kernel whether you enable
+ it or not, it is a compatibility placeholder.
+
+ Say N if unsure.
+
+config DEBUG_PERF_USE_VMALLOC
+ default n
+ bool "Debug: use vmalloc to back perf mmap() buffers"
+ depends on PERF_EVENTS && DEBUG_KERNEL
+ select PERF_USE_VMALLOC
+ help
+ Use vmalloc memory to back perf mmap() buffers.
+
+ Mostly useful for debugging the vmalloc code on platforms
+ that don't require it.
+
+ Say N if unsure.
+
+endmenu
+
config VM_EVENT_COUNTERS
default y
bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
on EMBEDDED systems. /proc/vmstat will only show page counts
if VM event counters are disabled.
+config PCI_QUIRKS
+ default y
+ bool "Enable PCI quirk workarounds" if EMBEDDED
+ depends on PCI
+ help
+ This enables workarounds for various PCI chipset
+ bugs/quirks. Disable this only if your target machine is
+ unaffected by PCI quirks.
+
config SLUB_DEBUG
default y
bool "Enable SLUB debugging support" if EMBEDDED
- depends on SLUB
+ depends on SLUB && SYSFS
help
SLUB has extensive debug support features. Disabling these can
result in significant savings in code size. This also disables
SLUB sysfs support. /sys/slab will not exist and there will be
no support for cache validation etc.
+config COMPAT_BRK
+ bool "Disable heap randomization"
+ default y
+ help
+ Randomizing heap placement makes heap exploits harder, but it
+ also breaks ancient binaries (including anything libc5 based).
+ This option changes the bootup default to heap randomization
+ disabled, and can be overridden at runtime by setting
+ /proc/sys/kernel/randomize_va_space to 2.
+
+ On non-ancient distros (post-2000 ones) N is usually a safe choice.
+
choice
prompt "Choose SLAB allocator"
default SLUB
help
The regular slab allocator that is established and known to work
well in all environments. It organizes cache hot objects in
- per cpu and per node queues. SLAB is the default choice for
- a slab allocator.
+ per cpu and per node queues.
config SLUB
bool "SLUB (Unqueued Allocator)"
instead of managing queues of cached objects (SLAB approach).
Per cpu caching is realized using slabs of objects instead
of queues of objects. SLUB can use memory efficiently
- and has enhanced diagnostics.
+ and has enhanced diagnostics. SLUB is the default choice for
+ a slab allocator.
config SLOB
depends on EMBEDDED
bool "SLOB (Simple Allocator)"
help
- SLOB replaces the SLAB allocator with a drastically simpler
- allocator. SLOB is more space efficient than SLAB but does not
- scale well (single lock for all operations) and is also highly
- susceptible to fragmentation. SLUB can accomplish a higher object
- density. It is usually better to use SLUB instead of SLOB.
+ SLOB replaces the stock allocator with a drastically simpler
+ allocator. SLOB is generally more space efficient but
+ does not perform as well on large systems.
endchoice
+config MMAP_ALLOW_UNINITIALIZED
+ bool "Allow mmapped anonymous memory to be uninitialized"
+ depends on EMBEDDED && !MMU
+ default n
+ help
+ Normally, and according to the Linux spec, anonymous memory obtained
+ from mmap() has it's contents cleared before it is passed to
+ userspace. Enabling this config option allows you to request that
+ mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
+ providing a huge performance boost. If this option is not enabled,
+ then the flag will be ignored.
+
+ This is taken advantage of by uClibc's malloc(), and also by
+ ELF-FDPIC binfmt's brk and stack allocator.
+
+ Because of the obvious security issues, this option should only be
+ enabled on embedded devices where you control what is run in
+ userspace. Since that isn't generally a problem on no-MMU systems,
+ it is normally safe to say Y here.
+
+ See Documentation/nommu-mmap.txt for more information.
+
+config PROFILING
+ bool "Profiling support"
+ help
+ Say Y here to enable the extended profiling support mechanisms used
+ by profilers such as OProfile.
+
+#
+# Place an empty function call at each tracepoint site. Can be
+# dynamically changed for a probe function.
+#
+config TRACEPOINTS
+ bool
+
+source "arch/Kconfig"
+
+config SLOW_WORK
+ default n
+ bool
+ help
+ The slow work thread pool provides a number of dynamically allocated
+ threads that can be used by the kernel to perform operations that
+ take a relatively long time.
+
+ An example of this would be CacheFiles doing a path lookup followed
+ by a series of mkdirs and a create call, all of which have to touch
+ disk.
+
+ See Documentation/slow-work.txt.
+
+config SLOW_WORK_DEBUG
+ bool "Slow work debugging through debugfs"
+ default n
+ depends on SLOW_WORK && DEBUG_FS
+ help
+ Display the contents of the slow work run queue through debugfs,
+ including items currently executing.
+
+ See Documentation/slow-work.txt.
+
endmenu # General setup
-config RT_MUTEXES
- boolean
- select PLIST
+config HAVE_GENERIC_DMA_COHERENT
+ bool
+ default n
-config TINY_SHMEM
- default !SHMEM
+config SLABINFO
bool
+ depends on PROC_FS
+ depends on SLAB || SLUB_DEBUG
+ default y
+
+config RT_MUTEXES
+ boolean
config BASE_SMALL
int
If unsure, say Y.
+if MODULES
+
+config MODULE_FORCE_LOAD
+ bool "Forced module loading"
+ default n
+ help
+ Allow loading of modules without version information (ie. modprobe
+ --force). Forced module loading sets the 'F' (forced) taint flag and
+ is usually a really bad idea.
+
config MODULE_UNLOAD
bool "Module unloading"
- depends on MODULES
help
Without this option you will not be able to unload any
modules (note that some modules may not be unloadable
- anyway), which makes your kernel slightly smaller and
- simpler. If unsure, say Y.
+ anyway), which makes your kernel smaller, faster
+ and simpler. If unsure, say Y.
config MODULE_FORCE_UNLOAD
bool "Forced module unloading"
config MODVERSIONS
bool "Module versioning support"
- depends on MODULES
help
Usually, you have to use modules compiled with your kernel.
Saying Y here makes it sometimes possible to use modules
config MODULE_SRCVERSION_ALL
bool "Source checksum for all modules"
- depends on MODULES
help
Modules which contain a MODULE_VERSION get an extra "srcversion"
field inserted into their modinfo section, which contains a
the version). With this option, such a "srcversion" field
will be created for all modules. If unsure, say N.
-config KMOD
- bool "Automatic kernel module loading"
- depends on MODULES
+endif # MODULES
+
+config INIT_ALL_POSSIBLE
+ bool
help
- Normally when you have selected some parts of the kernel to
- be created as kernel modules, you must load them (using the
- "modprobe" command) before you can use them. If you say Y
- here, some parts of the kernel will be able to load modules
- automatically: when a part of the kernel needs a module, it
- runs modprobe with the appropriate arguments, thereby
- loading the module if it is available. If unsure, say Y.
+ Back when each arch used to define their own cpu_online_map and
+ cpu_possible_map, some of them chose to initialize cpu_possible_map
+ with all 1s, and others with all 0s. When they were centralised,
+ it was better to provide this option than to break all the archs
+ and have several arch maintainers pursuing me down dark alleys.
config STOP_MACHINE
bool
config PREEMPT_NOTIFIERS
bool
+
+config PADATA
+ depends on SMP
+ bool
+
+source "kernel/Kconfig.locks"
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