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config DEFCONFIG_LIST string depends on !UML option defconfig_list default "/lib/modules/$UNAME_RELEASE/.config" default "/etc/kernel-config" default "/boot/config-$UNAME_RELEASE" default "arch/$ARCH/defconfig" menu "Code maturity level options" config EXPERIMENTAL bool "Prompt for development and/or incomplete code/drivers" ---help--- Some of the various things that Linux supports (such as network drivers, file systems, network protocols, etc.) can be in a state of development where the functionality, stability, or the level of testing is not yet high enough for general use. This is usually known as the "alpha-test" phase among developers. If a feature is currently in alpha-test, then the developers usually discourage uninformed widespread use of this feature by the general public to avoid "Why doesn't this work?" type mail messages. However, active testing and use of these systems is welcomed. Just be aware that it may not meet the normal level of reliability or it may fail to work in some special cases. Detailed bug reports from people familiar with the kernel internals are usually welcomed by the developers (before submitting bug reports, please read the documents <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, <file:Documentation/BUG-HUNTING>, and <file:Documentation/oops-tracing.txt> in the kernel source). This option will also make obsoleted drivers available. These are drivers that have been replaced by something else, and/or are scheduled to be removed in a future kernel release. Unless you intend to help test and develop a feature or driver that falls into this category, or you have a situation that requires using these features, you should probably say N here, which will cause the configurator to present you with fewer choices. If you say Y here, you will be offered the choice of using features or drivers that are currently considered to be in the alpha-test phase. config BROKEN bool config BROKEN_ON_SMP bool depends on BROKEN || !SMP default y config LOCK_KERNEL bool depends on SMP || PREEMPT default y config INIT_ENV_ARG_LIMIT int default 32 if !UML default 128 if UML help Maximum of each of the number of arguments and environment variables passed to init from the kernel command line. endmenu menu "General setup" config LOCALVERSION string "Local version - append to kernel release" help Append an extra string to the end of your kernel version. This will show up when you type uname, for example. The string you set here will be appended after the contents of any files with a filename matching localversion* in your object and source tree, in that order. Your total string can be a maximum of 64 characters. config LOCALVERSION_AUTO bool "Automatically append version information to the version string" default y help This will try to automatically determine if the current tree is a release tree by looking for git tags that belong to the current top of tree revision. A string of the format -gxxxxxxxx will be added to the localversion if a git based tree is found. The string generated by this will be appended after any matching localversion* files, and after the value set in CONFIG_LOCALVERSION Note: This requires Perl, and a git repository, but not necessarily the git or cogito tools to be installed. config VERSION_SIGNATURE string "Arbitrary version signature" help This string will be created in a file, /proc/version_signature. It is useful in determining arbitrary data about your kernel. For instance, if you have several kernels of the same version, but need to keep track of a revision of the same kernel, but not affect it's ability to load compatible modules, this is the easiest way to do that. config SWAP bool "Support for paging of anonymous memory (swap)" depends on MMU && BLOCK default y help This option allows you to choose whether you want to have support for so called swap devices or swap files in your kernel that are used to provide more virtual memory than the actual RAM present in your computer. If unsure say Y. config SYSVIPC bool "System V IPC" ---help--- Inter Process Communication is a suite of library functions and system calls which let processes (running programs) synchronize and exchange information. It is generally considered to be a good thing, and some programs won't run unless you say Y here. In particular, if you want to run the DOS emulator dosemu under Linux (read the DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), you'll need to say Y here. You can find documentation about IPC with "info ipc" and also in section 6.4 of the Linux Programmer's Guide, available from <http://www.tldp.org/guides.html>. config IPC_NS bool "IPC Namespaces" depends on SYSVIPC default n help Support ipc namespaces. This allows containers, i.e. virtual environments, to use ipc namespaces to provide different ipc objects for different servers. If unsure, say N. config POSIX_MQUEUE bool "POSIX Message Queues" depends on NET && EXPERIMENTAL ---help--- POSIX variant of message queues is a part of IPC. In POSIX message queues every message has a priority which decides about succession of receiving it by a process. If you want to compile and run programs written e.g. for Solaris with use of its POSIX message queues (functions mq_*) say Y here. To use this feature you will also need mqueue library, available from <http://www.mat.uni.torun.pl/~wrona/posix_ipc/> POSIX message queues are visible as a filesystem called 'mqueue' and can be mounted somewhere if you want to do filesystem operations on message queues. If unsure, say Y. config BSD_PROCESS_ACCT bool "BSD Process Accounting" help If you say Y here, a user level program will be able to instruct the kernel (via a special system call) to write process accounting information to a file: whenever a process exits, information about that process will be appended to the file by the kernel. The information includes things such as creation time, owning user, command name, memory usage, controlling terminal etc. (the complete list is in the struct acct in <file:include/linux/acct.h>). It is up to the user level program to do useful things with this information. This is generally a good idea, so say Y. config BSD_PROCESS_ACCT_V3 bool "BSD Process Accounting version 3 file format" depends on BSD_PROCESS_ACCT default n help If you say Y here, the process accounting information is written in a new file format that also logs the process IDs of each 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/>. config TASKSTATS bool "Export task/process statistics through netlink (EXPERIMENTAL)" depends on NET default n help Export selected statistics for tasks/processes through the generic netlink interface. Unlike BSD process accounting, the statistics are available during the lifetime of tasks/processes as responses to commands. Like BSD accounting, they are sent to user space on task exit. Say N if unsure. config TASK_DELAY_ACCT bool "Enable per-task delay accounting (EXPERIMENTAL)" depends on TASKSTATS help Collect information on time spent by a task waiting for system resources like cpu, synchronous block I/O completion and swapping in pages. Such statistics can help in setting a task's priorities relative to other tasks for cpu, io, rss limits etc. Say N if unsure. config UTS_NS bool "UTS Namespaces" default n help Support uts namespaces. This allows containers, i.e. vservers, to use uts namespaces to provide different uts info for different servers. If unsure, say N. config AUDIT bool "Auditing support" depends on NET help Enable auditing infrastructure that can be used with another kernel subsystem, such as SELinux (which requires this for logging of avc messages output). Does not do system-call auditing without CONFIG_AUDITSYSCALL. config AUDITSYSCALL bool "Enable system-call auditing support" depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64) default y if SECURITY_SELINUX help Enable low-overhead system-call auditing infrastructure that can be used independently or with another kernel subsystem, such as SELinux. To use audit's filesystem watch feature, please ensure that INOTIFY is configured. config IKCONFIG tristate "Kernel .config support" ---help--- This option enables the complete Linux kernel ".config" file contents to be saved in the kernel. It provides documentation of which kernel options are used in a running kernel or in an on-disk kernel. This information can be extracted from the kernel image file with the script scripts/extract-ikconfig and used as input to rebuild the current kernel or to build another kernel. It can also be extracted from a running kernel by reading /proc/config.gz if enabled (below). config IKCONFIG_PROC bool "Enable access to .config through /proc/config.gz" depends on IKCONFIG && PROC_FS ---help--- This option enables access to the kernel configuration file through /proc/config.gz. config CPUSETS bool "Cpuset support" depends on SMP help This option will let you create and manage CPUSETs which allow dynamically partitioning a system into sets of CPUs and Memory Nodes and assigning tasks to run only within those sets. This is primarily useful on large SMP or NUMA systems. Say N if unsure. config SYSFS_DEPRECATED bool "Create deprecated sysfs files" default y 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 heirachy, in order to support older versions of udev. If you are using a distro that was released in 2006 or later, it should be safe to say N here. config RELAY bool "Kernel->user space relay support (formerly relayfs)" help This option enables support for relay interface support in certain file systems (such as debugfs). It is designed to provide an efficient mechanism for tools and facilities to relay large amounts of data from kernel space to user space. If unsure, say N. source "usr/Kconfig" config CC_OPTIMIZE_FOR_SIZE bool "Optimize for size (Look out for broken compilers!)" default y depends on ARM || H8300 || 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. config TASK_XACCT bool "Enable extended accounting over taskstats (EXPERIMENTAL)" depends on TASKSTATS help Collect extended task accounting data and send the data to userland for processing over the taskstats interface. Say N if unsure. config TASK_IO_ACCOUNTING bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" depends on TASK_XACCT help Collect information on the number of bytes of storage I/O which this task has caused. Say N if unsure. config SYSCTL bool menuconfig EMBEDDED bool "Configure standard kernel features (for small systems)" help This option allows certain base kernel options and settings to be disabled or tweaked. This is for specialized environments which can tolerate a "non-standard" kernel. Only use this if you really know what you are doing. config UID16 bool "Enable 16-bit UID system calls" if EMBEDDED depends on ARM || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_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 default y select SYSCTL ---help--- sys_sysctl uses binary paths that have been found challenging to properly maintain and use. The interface in /proc/sys using paths with ascii names is now the primary path to this information. Almost nothing using the binary sysctl interface so if you are trying to save some space it is probably safe to disable this, making your kernel marginally smaller. If unsure say Y here. config KALLSYMS bool "Load all symbols for debugging/ksymoops" if EMBEDDED default y help Say Y here to let the kernel print out symbolic crash information and symbolic stack backtraces. This increases the size of the kernel somewhat, as all symbols have to be loaded into the kernel image. config KALLSYMS_ALL bool "Include all symbols in kallsyms" depends on DEBUG_KERNEL && KALLSYMS help Normally kallsyms only contains the symbols of functions, for nicer OOPS messages. Some debuggers can use kallsyms for other symbols too: say Y here to include all symbols, if you need them and you don't care about adding 300k to the size of your kernel. Say N. config KALLSYMS_EXTRA_PASS bool "Do an extra kallsyms pass" depends on KALLSYMS help If kallsyms is not working correctly, the build will fail with inconsistent kallsyms data. If that occurs, log a bug report and turn on KALLSYMS_EXTRA_PASS which should result in a stable build. Always say N here unless you find a bug in kallsyms, which must be reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while you wait for kallsyms to be fixed. config HOTPLUG bool "Support for hot-pluggable devices" if EMBEDDED default y help This option is provided for the case where no hotplug or uevent capabilities is wanted by the kernel. You should only consider disabling this option for embedded systems that do not use modules, a dynamic /dev tree, or dynamic device discovery. Just say Y. config PRINTK default y bool "Enable support for printk" if EMBEDDED help This option enables normal printk support. Removing it eliminates most of the message strings from the kernel image and makes the kernel more or less silent. As this makes it very difficult to diagnose system problems, saying N here is strongly discouraged. config BUG bool "BUG() support" if EMBEDDED default y help Disabling this option eliminates support for BUG and WARN, reducing the size of your kernel image and potentially quietly ignoring numerous fatal conditions. You should only consider disabling this option for embedded systems with no facilities for reporting errors. Just say Y. config ELF_CORE default y bool "Enable ELF core dumps" if EMBEDDED help Enable support for generating core dumps. Disabling saves about 4k. config BASE_FULL default y bool "Enable full-sized data structures for core" if EMBEDDED help Disabling this option reduces the size of miscellaneous core kernel data structures. This saves memory on small machines, but may reduce performance. config FUTEX bool "Enable futex support" if EMBEDDED default y select RT_MUTEXES help Disabling this option will cause the kernel to be built without support for "fast userspace mutexes". The resulting kernel may not run glibc-based applications correctly. config EPOLL bool "Enable eventpoll support" if EMBEDDED default y help Disabling this option will cause the kernel to be built without support for epoll family of system calls. config SHMEM bool "Use full shmem filesystem" if EMBEDDED default y depends on MMU help The shmem is an internal filesystem used to manage shared memory. It is backed by swap and manages resource limits. It is also exported to userspace as tmpfs if TMPFS is enabled. Disabling this option replaces shmem and tmpfs with the much simpler ramfs code, which may be appropriate on small systems without swap. config SLAB default y bool "Use full SLAB allocator" if (EMBEDDED && !SMP && !SPARSEMEM) help Disabling this replaces the advanced SLAB allocator and kmalloc support with the drastically simpler SLOB allocator. SLOB is more space efficient but does not scale well and is more susceptible to fragmentation. config VM_EVENT_COUNTERS default y bool "Enable VM event counters for /proc/vmstat" if EMBEDDED help VM event counters are needed for event counts to be shown. This option allows the disabling of the VM event counters on EMBEDDED systems. /proc/vmstat will only show page counts if VM event counters are disabled. endmenu # General setup config RT_MUTEXES boolean select PLIST config TINY_SHMEM default !SHMEM bool config BASE_SMALL int default 0 if BASE_FULL default 1 if !BASE_FULL config SLOB default !SLAB bool menu "Loadable module support" config MODULES bool "Enable loadable module support" help Kernel modules are small pieces of compiled code which can be inserted in the running kernel, rather than being permanently built into the kernel. You use the "modprobe" tool to add (and sometimes remove) them. If you say Y here, many parts of the kernel can be built as modules (by answering M instead of Y where indicated): this is most useful for infrequently used options which are not required for booting. For more information, see the man pages for modprobe, lsmod, modinfo, insmod and rmmod. If you say Y here, you will need to run "make modules_install" to put the modules under /lib/modules/ where modprobe can find them (you may need to be root to do this). If unsure, say Y. 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. config MODULE_FORCE_UNLOAD bool "Forced module unloading" depends on MODULE_UNLOAD && EXPERIMENTAL help This option allows you to force a module to unload, even if the kernel believes it is unsafe: the kernel will remove the module without waiting for anyone to stop using it (using the -f option to rmmod). This is mainly for kernel developers and desperate users. If unsure, say N. 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 compiled for different kernels, by adding enough information to the modules to (hopefully) spot any changes which would make them incompatible with the kernel you are running. If unsure, say N. 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 sum of the source files which made it. This helps maintainers see exactly which source was used to build a module (since others sometimes change the module source without updating 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 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. config STOP_MACHINE bool default y depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU help Need stop_machine() primitive. endmenu menu "Block layer" source "block/Kconfig" endmenu