bool
config SYSFS_DEPRECATED_V2
- bool "Create deprecated sysfs files"
+ bool "Create deprecated sysfs layout for older userspace tools"
depends on SYSFS
default y
select SYSFS_DEPRECATED
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 and some userspace
- programs.
-
- If you are using a distro with the most recent userspace
- packages, it should be safe to say N here.
+ 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 PROC_PID_CPUSET
bool "Include legacy /proc/<pid>/cpuset file"
boolean
select PLIST
-config TINY_SHMEM
- default !SHMEM
- bool
-
config BASE_SMALL
int
default 0 if BASE_FULL
the version). With this option, such a "srcversion" field
will be created for all modules. If unsure, say N.
-config KMOD
- def_bool y
- help
- This is being removed soon. These days, CONFIG_MODULES
- implies CONFIG_KMOD, so use that instead.
-
endif # MODULES
+config INIT_ALL_POSSIBLE
+ bool
+ help
+ 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
default y
config PREEMPT_NOTIFIERS
bool
+choice
+ prompt "RCU Implementation"
+ default CLASSIC_RCU
+
config CLASSIC_RCU
- def_bool !PREEMPT_RCU
+ bool "Classic RCU"
help
This option selects the classic RCU implementation that is
designed for best read-side performance on non-realtime
- systems. Classic RCU is the default. Note that the
- PREEMPT_RCU symbol is used to select/deselect this option.
+ 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.
projects / linux-2.6-omap-h63xx.git / blobdiff