default "/lib/modules/$UNAME_RELEASE/.config"
default "/etc/kernel-config"
default "/boot/config-$UNAME_RELEASE"
+ default "$ARCH_DEFCONFIG"
default "arch/$ARCH/defconfig"
menu "General setup"
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 PID_NS
- bool "PID Namespaces (EXPERIMENTAL)"
- default n
- depends on EXPERIMENTAL
- help
- Suport process id namespaces. This allows having multiple
- process 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 AUDIT
bool "Auditing support"
depends on NET
def_bool y
depends on AUDITSYSCALL && INOTIFY
+menu "RCU Subsystem"
+
+choice
+ prompt "RCU Implementation"
+ default CLASSIC_RCU
+
+config CLASSIC_RCU
+ bool "Classic RCU"
+ help
+ This option selects the classic RCU implementation that is
+ designed for best read-side performance on non-realtime
+ systems.
+
+ Select this option if you are unsure.
+
+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.
+
+config PREEMPT_RCU
+ bool "Preemptible RCU"
+ depends on PREEMPT
+ help
+ This option reduces the latency of the kernel by making certain
+ RCU sections preemptible. Normally RCU code is non-preemptible, if
+ this option is selected then read-only RCU sections become
+ preemptible. This helps latency, but may expose bugs due to
+ now-naive assumptions about each RCU read-side critical section
+ remaining on a given CPU through its execution.
+
+endchoice
+
+config RCU_TRACE
+ bool "Enable tracing for RCU"
+ depends on TREE_RCU || 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
+ 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
+ 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 TREE_RCU_TRACE
+ def_bool RCU_TRACE && TREE_RCU
+ select DEBUG_FS
+ help
+ This option provides tracing for the TREE_RCU implementation,
+ permitting Makefile to trivially select kernel/rcutree_trace.c.
+
+config PREEMPT_RCU_TRACE
+ def_bool RCU_TRACE && PREEMPT_RCU
+ select DEBUG_FS
+ help
+ This option provides tracing for the PREEMPT_RCU implementation,
+ permitting Makefile to trivially select kernel/rcupreempt_trace.c.
+
+endmenu # "RCU Subsystem"
+
config IKCONFIG
tristate "Kernel .config support"
---help---
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
+
+config GROUP_SCHED
+ bool "Group CPU scheduler"
+ depends on EXPERIMENTAL
+ default n
+ help
+ This feature lets CPU scheduler recognize task groups and control CPU
+ bandwidth allocation to such task groups.
+ In order to create a group from arbitrary set of processes, use
+ CONFIG_CGROUPS. (See Control Group support.)
+
+config FAIR_GROUP_SCHED
+ bool "Group scheduling for SCHED_OTHER"
+ depends on GROUP_SCHED
+ default GROUP_SCHED
+
+config RT_GROUP_SCHED
+ bool "Group scheduling for SCHED_RR/FIFO"
+ depends on EXPERIMENTAL
+ depends on GROUP_SCHED
+ default n
+ help
+ 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.
+
+choice
+ depends on GROUP_SCHED
+ prompt "Basis for grouping tasks"
+ default USER_SCHED
+
+config USER_SCHED
+ bool "user id"
help
- This option will let you use process cgroup subsystems
- such as Cpusets
+ This option will choose userid as the basis for grouping
+ tasks, thus providing equal CPU bandwidth to each user.
+
+config 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/cgroups.txt for more
+ information on "cgroup" pseudo filesystem.
+
+endchoice
+
+menuconfig CGROUPS
+ boolean "Control Group support"
+ help
+ 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_FREEZER
+ bool "Freezer cgroup subsystem"
+ depends on CGROUPS
+ help
+ 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"
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
- help
- This feature lets CPU scheduler recognize task groups and control CPU
- bandwidth allocation to such task groups.
-
-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.
-
-endchoice
config CGROUP_CPUACCT
bool "Simple CPU accounting cgroup subsystem"
depends on CGROUPS
help
Provides a simple Resource Controller for monitoring the
- total CPU consumed by the tasks in a cgroup
+ total CPU consumed by the tasks in a cgroup.
config RESOURCE_COUNTERS
bool "Resource counters"
help
This option enables controller independent resource accounting
- infrastructure that works with cgroups
+ infrastructure that works with cgroups.
depends on CGROUPS
-config SYSFS_DEPRECATED
- bool "Create deprecated sysfs files"
- depends on SYSFS
- default y
+config CGROUP_MEM_RES_CTLR
+ bool "Memory Resource Controller for Control Groups"
+ depends on CGROUPS && RESOURCE_COUNTERS
+ select MM_OWNER
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.
-
- 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.
+ Provides a memory resource controller that manages both anonymous
+ memory and page cache. (See Documentation/controllers/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.
+
+endif # CGROUPS
+
+config MM_OWNER
+ bool
- If you are using a distro that was released in 2006 or later,
- it should be safe to say N here.
+config SYSFS_DEPRECATED
+ bool
-config PROC_PID_CPUSET
- bool "Include legacy /proc/<pid>/cpuset file"
- depends on CPUSETS
+config SYSFS_DEPRECATED_V2
+ bool "Create deprecated sysfs layout for older userspace tools"
+ depends on SYSFS
default y
+ select SYSFS_DEPRECATED
+ help
+ This option switches the layout of sysfs to the deprecated
+ version.
+
+ 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
+ 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
+ process 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 || BLACKFIN || 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.
help
Enable support for generating core dumps. Disabling saves about 4k.
-config COMPAT_BRK
- bool "Disable heap randomization"
+config PCSPKR_PLATFORM
+ bool "Enable PC-Speaker support" if EMBEDDED
+ depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
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 overriden runtime by setting
- /proc/sys/kernel/randomize_va_space to 2.
-
- On non-ancient distros (post-2000 ones) Y is usually a safe choice.
+ This option allows to disable the internal PC-Speaker
+ support, saving some memory.
config BASE_FULL
default y
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
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 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 overriden 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
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
+
config MARKERS
bool "Activate markers"
+ depends on TRACEPOINTS
help
Place an empty function call at each marker site. Can be
dynamically changed for a probe function.
source "arch/Kconfig"
-config PROC_PAGE_MONITOR
- default y
- depends on PROC_FS && MMU
- bool "Enable /proc page monitoring" if EMBEDDED
- help
- Various /proc files exist to monitor process memory utilization:
- /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
- /proc/kpagecount, and /proc/kpageflags. Disabling these
- interfaces will reduce the size of the kernel by approximately 4kb.
-
endmenu # General setup
+config HAVE_GENERIC_DMA_COHERENT
+ bool
+ default n
+
config SLABINFO
bool
depends on PROC_FS
- depends on SLAB || SLUB
+ depends on SLAB || SLUB_DEBUG
default y
config RT_MUTEXES
boolean
- select PLIST
-
-config TINY_SHMEM
- default !SHMEM
- bool
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 persuing me down dark alleys.
config STOP_MACHINE
bool
config PREEMPT_NOTIFIERS
bool
-choice
- prompt "RCU implementation type:"
- default CLASSIC_RCU
- help
- This allows you to choose either the classic RCU implementation
- that is designed for best read-side performance on non-realtime
- systems, or the preemptible RCU implementation for best latency
- on realtime systems. Note that some kernel preemption modes
- will restrict your choice.
-
- Select the default if you are unsure.
-
-config CLASSIC_RCU
- bool "Classic RCU"
- help
- This option selects the classic RCU implementation that is
- designed for best read-side performance on non-realtime
- systems.
-
- Say Y if you are unsure.
-
-config PREEMPT_RCU
- bool "Preemptible RCU"
- depends on PREEMPT
- help
- This option reduces the latency of the kernel by making certain
- RCU sections preemptible. Normally RCU code is non-preemptible, if
- this option is selected then read-only RCU sections become
- preemptible. This helps latency, but may expose bugs due to
- now-naive assumptions about each RCU read-side critical section
- remaining on a given CPU through its execution.
-
- Say N if you are unsure.
-
-endchoice
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff