diff options
Diffstat (limited to 'init/Kconfig')
| -rw-r--r-- | init/Kconfig | 74 |
1 files changed, 38 insertions, 36 deletions
diff --git a/init/Kconfig b/init/Kconfig index 2de5b1cbadd9..51269b102d2b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -179,7 +179,7 @@ config KERNEL_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 + size is about 10% bigger than gzip; however its speed (both compression and decompression) is the fastest. endchoice @@ -340,6 +340,7 @@ choice config TREE_RCU bool "Tree-based hierarchical RCU" + depends on !PREEMPT && SMP help This option selects the RCU implementation that is designed for very large SMP system with hundreds or @@ -347,7 +348,7 @@ config TREE_RCU smaller systems. config TREE_PREEMPT_RCU - bool "Preemptable tree-based hierarchical RCU" + bool "Preemptible tree-based hierarchical RCU" depends on PREEMPT help This option selects the RCU implementation that is @@ -365,8 +366,22 @@ config TINY_RCU is not required. This option greatly reduces the memory footprint of RCU. +config TINY_PREEMPT_RCU + bool "Preemptible UP-only small-memory-footprint RCU" + depends on !SMP && PREEMPT + help + This option selects the RCU implementation that is designed + for real-time UP systems. This option greatly reduces the + memory footprint of RCU. + endchoice +config PREEMPT_RCU + def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) + help + This option enables preemptible-RCU code that is common between + the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. + config RCU_TRACE bool "Enable tracing for RCU" depends on TREE_RCU || TREE_PREEMPT_RCU @@ -387,9 +402,12 @@ config RCU_FANOUT 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. + large numbers of CPUs. This value must be at least the fourth + root of NR_CPUS, which allows NR_CPUS to be insanely large. + The default value of RCU_FANOUT should be used for production + systems, but if you are stress-testing the RCU implementation + itself, small RCU_FANOUT values allow you to test large-system + code paths on small(er) systems. Select a specific number if testing RCU itself. Take the default if unsure. @@ -656,40 +674,24 @@ 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. + help + This option switches the layout of the "block" class devices, to not + show up in /sys/class/block/, but only in /sys/block/. + + This option allows new kernels to run on old distributions and tools, + which might get confused by /sys/class/block/. Since 2007/2008 all + major distributions and tools handle this just fine. + + Recent distributions and userspace tools after 2009/2010 depend on + the existence of /sys/class/block/, and will not work with this + option enabled. + + Only if you are using a new kernel on an old distribution, you might + need to say Y here. Never say Y, if the original kernel, that came + with your distribution, has not set this option. config RELAY bool "Kernel->user space relay support (formerly relayfs)" |