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 , , , , and 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 These are drivers that have been replaced by something else, and/or are scheduled to be removed in a future kernel release.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 CLEAN_COMPILE bool "Select only drivers expected to compile cleanly" if EXPERIMENTAL default y help Select this option if you don't even want to see the option to configure known-broken drivers. If unsure, say Y config BROKEN bool depends on !CLEAN_COMPILE default y config BROKEN_ON_SMP bool depends on BROKEN || !SMP default y config LOCK_KERNEL bool depends on SMP || PREEMPT default y 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 SWAP bool "Support for paging of anonymous memory (swap)" depends on MMU default y help This option allows you to choose whether you want to have support for socalled 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" depends on MMU ---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 ), 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 . 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 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 ). 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 . menu "Class Based Kernel Resource Management" config CKRM bool "Class Based Kernel Resource Management Core" depends on EXPERIMENTAL help Class-based Kernel Resource Management is a framework for controlling and monitoring resource allocation of user-defined groups of tasks or incoming socket connections. For more information, please visit http://ckrm.sf.net. If you say Y here, enable the Resource Class File System and atleast one of the resource controllers below. Say N if you are unsure. config RCFS_FS tristate "Resource Class File System (User API)" depends on CKRM help RCFS is the filesystem API for CKRM. This separate configuration option is provided only for debugging and will eventually disappear since rcfs will be automounted whenever CKRM is configured. Say N if unsure, Y if you've enabled CKRM, M to debug rcfs initialization. config CKRM_TYPE_TASKCLASS bool "Class Manager for Task Groups" depends on CKRM && RCFS_FS help TASKCLASS provides the extensions for CKRM to track task classes This is the base to enable task class based resource control for cpu, memory and disk I/O. Say N if unsure config CKRM_RES_NULL tristate "Null Tasks Resource Manager" depends on CKRM_TYPE_TASKCLASS default m help Provides a Null Resource Controller for CKRM that is purely for demonstration purposes. Say N if unsure, Y to use the feature. config CKRM_RES_NUMTASKS tristate "Number of Tasks Resource Manager" depends on CKRM_TYPE_TASKCLASS default m help Provides a Resource Controller for CKRM that allows limiting no of tasks a task class can have. Say N if unsure, Y to use the feature. config CKRM_CPU_SCHEDULE bool "CKRM CPU scheduler" depends on CKRM_TYPE_TASKCLASS default y help Use CKRM CPU scheduler instead of Linux Scheduler Say N if unsure, Y to use the feature. config CKRM_RES_BLKIO tristate " Disk I/O Resource Controller" depends on CKRM_TYPE_TASKCLASS && IOSCHED_CFQ default m help Provides a resource controller for best-effort block I/O bandwidth control. The controller attempts this by proportional servicing of requests in the I/O scheduler. However, seek optimizations and reordering by device drivers/disk controllers may alter the actual bandwidth delivered to a class. Say N if unsure, Y to use the feature. config CKRM_RES_MEM bool "Class based physical memory controller" default y depends on CKRM help Provide the basic support for collecting physical memory usage information among classes. Say Y if you want to know the memory usage of each class. config CKRM_MEM_LRUORDER_CHANGE bool "Change the LRU ordering of scanned pages" default n depends on CKRM_RES_MEM help While trying to free pages, by default(n), scanned pages are left were they are found if they belong to relatively under-used class. In this case the LRU ordering of the memory subsystemis left intact. If this option is chosen, then the scanned pages are moved to the tail of the list(active or inactive). Changing this to yes reduces the checking overhead but violates the approximate LRU order that is maintained by the paging subsystem. config CKRM_CPU_SCHEDULE_AT_BOOT bool "Turn on at boot time" depends on CKRM_CPU_SCHEDULE default n help Enable CKRM CPU Scheduler at boot time. Otherwise it can be turned on dynamically at runtime. If not turned on the default Linux Scheduler behavior will be obtained. Say N if unsure, Y to use this feature config CKRM_TYPE_SOCKETCLASS bool "Class Manager for socket groups" depends on CKRM help SOCKET provides the extensions for CKRM to track per socket classes. This is the base to enable socket based resource control for inbound connection control, bandwidth control etc. Say N if unsure. config CKRM_RES_LISTENAQ tristate "Multiple Accept Queues Resource Manager" depends on CKRM_TYPE_SOCKETCLASS && ACCEPT_QUEUES default m help Provides a resource controller for CKRM to prioritize inbound connection requests. See inbound control description for "IP: TCP Multiple accept queues support". If you choose that option choose this option to control the queue weights. If unsure, say N. choice prompt "Classification Engine" depends on CKRM && RCFS_FS optional help Select a classification engine (CE) that assists in automatic classification of kernel objects managed by CKRM when they are created. Without a CE, a user must manually classify objects into classes. Processes inherit their parent's classification. Only one engine can be built into the kernel though all can be built as modules (only one will load). If unsure, say N. config CKRM_RBCE tristate "Vanilla RBCE" help Vanilla Rule-based Classification Engine (RBCE). Rules for classifying kernel objects are created/deleted/modified through a RCFS directory using a filesystem interface. Any CE is optional. If unsure, say N. config CKRM_CRBCE tristate "Enhanced RBCE" depends on DELAY_ACCT && RELAYFS_FS help Enhanced Rule-based Classification Engine (CRBCE). Like the Vanilla RBCE, rules for classifying kernel objects are created, deleted and modified through a RCFS directory using a filesystem interface (requires CKRM_RCFS configured). In addition, CRBCE provides per-process delay data (requires DELAY_ACCT configured) and makes information on significant kernel events available to userspace tools through relayfs (requires RELAYFS_FS configured). Any CE is optional. If unsure, say N. endchoice endmenu config SYSCTL bool "Sysctl support" ---help--- The sysctl interface provides a means of dynamically changing certain kernel parameters and variables on the fly without requiring a recompile of the kernel or reboot of the system. The primary interface consists of a system call, but if you say Y to "/proc file system support", a tree of modifiable sysctl entries will be generated beneath the /proc/sys directory. They are explained in the files in . Note that enabling this option will enlarge the kernel by at least 8 KB. As it is generally a good thing, you should say Y here unless building a kernel for install/rescue disks or your system is very limited in memory. config AUDIT bool "Auditing support" default y if SECURITY_SELINUX default n 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 || PPC64 || ARCH_S390 || IA64) default y if SECURITY_SELINUX default n help Enable low-overhead system-call auditing infrastructure that can be used independently or with another kernel subsystem, such as SELinux. config LOG_BUF_SHIFT int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL range 12 21 default 17 if ARCH_S390 default 16 if X86_NUMAQ || IA64 default 15 if SMP default 14 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 13 => 8 KB 12 => 4 KB config HOTPLUG bool "Support for hot-pluggable devices" if !ARCH_S390 default ARCH_S390 help Say Y here if you want to plug devices into your computer while the system is running, and be able to use them quickly. In many cases, the devices can likewise be unplugged at any time too. One well known example of this is PCMCIA- or PC-cards, credit-card size devices such as network cards, modems or hard drives which are plugged into slots found on all modern laptop computers. Another example, used on modern desktops as well as laptops, is USB. Enable HOTPLUG and KMOD, and build a modular kernel. Get agent software (at ) and install it. Then your kernel will automatically call out to a user mode "policy agent" (/sbin/hotplug) to load modules and set up software needed to use devices as you hotplug them. config KOBJECT_UEVENT bool "Kernel Userspace Events" depends on NET default y help This option enables the kernel userspace event layer, which is a simple mechanism for kernel-to-user communication over a netlink socket. The goal of the kernel userspace events layer is to provide a simple and efficient events system, that notifies userspace about kobject state changes. This will enable applications to just listen for events instead of polling system devices and files. Hotplug events (kobject addition and removal) are also available on the netlink socket in addition to the execution of /sbin/hotplug if CONFIG_HOTPLUG is enabled. Say Y, unless you are building a system requiring minimal memory consumption. config IKCONFIG bool "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 OOM_PANIC bool "OOM Panic" default y ---help--- This option enables panic() to be called when a system is out of memory. This feature along with /proc/sys/kernel/panic allows a different behavior on out-of-memory conditions when the standard behavior (killing processes in an attempt to recover) does not make sense. If unsure, say N. config OOM_KILL bool depends on !OOM_PANIC default y 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 DELAY_ACCT bool "Enable delay accounting (EXPERIMENTAL)" help In addition to counting frequency the total delay in ns is also recorded. CPU delays are specified as cpu-wait and cpu-run. I/O delays are recorded for memory and regular I/O. Information is accessible through /proc//delay. config KALLSYMS bool "Load all symbols for debugging/kksymoops" 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, 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 FUTEX bool "Enable futex support" if EMBEDDED default y 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 CC_OPTIMIZE_FOR_SIZE bool "Optimize for size" default y if ARM || H8300 default n 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 SHMEM default y bool "Use full shmem filesystem" if EMBEDDED && 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 CC_ALIGN_FUNCTIONS int "Function alignment" if EMBEDDED default 0 help Align the start of functions to the next power-of-two greater than n, skipping up to n bytes. For instance, 32 aligns functions to the next 32-byte boundary, but 24 would align to the next 32-byte boundary only if this can be done by skipping 23 bytes or less. Zero means use compiler's default. config CC_ALIGN_LABELS int "Label alignment" if EMBEDDED default 0 help Align all branch targets to a power-of-two boundary, skipping up to n bytes like ALIGN_FUNCTIONS. This option can easily make code slower, because it must insert dummy operations for when the branch target is reached in the usual flow of the code. Zero means use compiler's default. config CC_ALIGN_LOOPS int "Loop alignment" if EMBEDDED default 0 help Align loops to a power-of-two boundary, skipping up to n bytes. Zero means use compiler's default. config CC_ALIGN_JUMPS int "Jump alignment" if EMBEDDED default 0 help Align branch targets to a power-of-two boundary, for branch targets where the targets can only be reached by jumping, skipping up to n bytes like ALIGN_FUNCTIONS. In this case, no dummy operations need be executed. Zero means use compiler's default. endmenu # General setup config TINY_SHMEM default !SHMEM 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 OBSOLETE_MODPARM bool default y depends on MODULES help You need this option to use module parameters on modules which have not been converted to the new module parameter system yet. If unsure, say Y. config MODVERSIONS bool "Module versioning support (EXPERIMENTAL)" depends on MODULES && EXPERIMENTAL 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 MODULE_SIG bool "Module signature verification (EXPERIMENTAL)" depends on MODULES && EXPERIMENTAL select CRYPTO select CRYPTO_SHA1 select CRYPTO_SIGNATURE help Check modules for valid signatures upon load. config MODULE_SIG_FORCE bool "Required modules to be validly signed (EXPERIMENTAL)" depends on MODULE_SIG help Reject unsigned modules or signed modules for which we don't have a key. 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