| config ARCH |
| string |
| option env="ARCH" |
| |
| config KERNELVERSION |
| string |
| option env="KERNELVERSION" |
| |
| 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 "$ARCH_DEFCONFIG" |
| default "arch/$ARCH/defconfig" |
| |
| config CONSTRUCTORS |
| bool |
| depends on !UML |
| |
| config IRQ_WORK |
| bool |
| |
| config BUILDTIME_EXTABLE_SORT |
| bool |
| |
| config THREAD_INFO_IN_TASK |
| bool |
| help |
| Select this to move thread_info off the stack into task_struct. To |
| make this work, an arch will need to remove all thread_info fields |
| except flags and fix any runtime bugs. |
| |
| One subtle change that will be needed is to use try_get_task_stack() |
| and put_task_stack() in save_thread_stack_tsk() and get_wchan(). |
| |
| menu "General setup" |
| |
| config BROKEN |
| bool |
| |
| config BROKEN_ON_SMP |
| bool |
| depends on BROKEN || !SMP |
| 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. |
| |
| |
| config CROSS_COMPILE |
| string "Cross-compiler tool prefix" |
| help |
| Same as running 'make CROSS_COMPILE=prefix-' but stored for |
| default make runs in this kernel build directory. You don't |
| need to set this unless you want the configured kernel build |
| directory to select the cross-compiler automatically. |
| |
| config COMPILE_TEST |
| bool "Compile also drivers which will not load" |
| depends on !UML |
| default n |
| help |
| Some drivers can be compiled on a different platform than they are |
| intended to be run on. Despite they cannot be loaded there (or even |
| when they load they cannot be used due to missing HW support), |
| developers still, opposing to distributors, might want to build such |
| drivers to compile-test them. |
| |
| If you are a developer and want to build everything available, say Y |
| here. If you are a user/distributor, say N here to exclude useless |
| drivers to be distributed. |
| |
| 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 |
| depends on !COMPILE_TEST |
| 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. |
| |
| (The actual string used here is the first eight characters produced |
| by running the command: |
| |
| $ git rev-parse --verify HEAD |
| |
| which is done within the script "scripts/setlocalversion".) |
| |
| config HAVE_KERNEL_GZIP |
| bool |
| |
| config HAVE_KERNEL_BZIP2 |
| bool |
| |
| config HAVE_KERNEL_LZMA |
| bool |
| |
| config HAVE_KERNEL_XZ |
| bool |
| |
| config HAVE_KERNEL_LZO |
| bool |
| |
| config HAVE_KERNEL_LZ4 |
| bool |
| |
| choice |
| prompt "Kernel compression mode" |
| default KERNEL_GZIP |
| depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 |
| help |
| The linux kernel is a kind of self-extracting executable. |
| Several compression algorithms are available, which differ |
| in efficiency, compression and decompression speed. |
| Compression speed is only relevant when building a kernel. |
| Decompression speed is relevant at each boot. |
| |
| If you have any problems with bzip2 or lzma compressed |
| kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older |
| version of this functionality (bzip2 only), for 2.4, was |
| supplied by Christian Ludwig) |
| |
| High compression options are mostly useful for users, who |
| are low on disk space (embedded systems), but for whom ram |
| size matters less. |
| |
| If in doubt, select 'gzip' |
| |
| config KERNEL_GZIP |
| bool "Gzip" |
| depends on HAVE_KERNEL_GZIP |
| help |
| The old and tried gzip compression. It provides a good balance |
| between compression ratio and decompression speed. |
| |
| config KERNEL_BZIP2 |
| bool "Bzip2" |
| depends on HAVE_KERNEL_BZIP2 |
| help |
| Its compression ratio and speed is intermediate. |
| Decompression speed is slowest among the choices. The kernel |
| size is about 10% smaller with bzip2, in comparison to gzip. |
| Bzip2 uses a large amount of memory. For modern kernels you |
| will need at least 8MB RAM or more for booting. |
| |
| config KERNEL_LZMA |
| bool "LZMA" |
| depends on HAVE_KERNEL_LZMA |
| help |
| This compression algorithm's ratio is best. Decompression speed |
| is between gzip and bzip2. Compression is slowest. |
| The kernel size is about 33% smaller with LZMA in comparison to gzip. |
| |
| config KERNEL_XZ |
| bool "XZ" |
| depends on HAVE_KERNEL_XZ |
| help |
| XZ uses the LZMA2 algorithm and instruction set specific |
| BCJ filters which can improve compression ratio of executable |
| code. The size of the kernel is about 30% smaller with XZ in |
| comparison to gzip. On architectures for which there is a BCJ |
| filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ |
| will create a few percent smaller kernel than plain LZMA. |
| |
| The speed is about the same as with LZMA: The decompression |
| speed of XZ is better than that of bzip2 but worse than gzip |
| and LZO. Compression is slow. |
| |
| config KERNEL_LZO |
| bool "LZO" |
| depends on HAVE_KERNEL_LZO |
| help |
| Its compression ratio is the poorest among the choices. The kernel |
| size is about 10% bigger than gzip; however its speed |
| (both compression and decompression) is the fastest. |
| |
| config KERNEL_LZ4 |
| bool "LZ4" |
| depends on HAVE_KERNEL_LZ4 |
| help |
| LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. |
| A preliminary version of LZ4 de/compression tool is available at |
| <https://code.google.com/p/lz4/>. |
| |
| Its compression ratio is worse than LZO. The size of the kernel |
| is about 8% bigger than LZO. But the decompression speed is |
| faster than LZO. |
| |
| endchoice |
| |
| config DEFAULT_HOSTNAME |
| string "Default hostname" |
| default "(none)" |
| help |
| This option determines the default system hostname before userspace |
| calls sethostname(2). The kernel traditionally uses "(none)" here, |
| but you may wish to use a different default here to make a minimal |
| system more usable with less configuration. |
| |
| 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 SYSVIPC_SYSCTL |
| bool |
| depends on SYSVIPC |
| depends on SYSCTL |
| default y |
| |
| config POSIX_MQUEUE |
| bool "POSIX Message Queues" |
| depends on NET |
| ---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. |
| |
| 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 POSIX_MQUEUE_SYSCTL |
| bool |
| depends on POSIX_MQUEUE |
| depends on SYSCTL |
| default y |
| |
| config CROSS_MEMORY_ATTACH |
| bool "Enable process_vm_readv/writev syscalls" |
| depends on MMU |
| default y |
| help |
| Enabling this option adds the system calls process_vm_readv and |
| process_vm_writev which allow a process with the correct privileges |
| to directly read from or write to another process' address space. |
| See the man page for more details. |
| |
| config FHANDLE |
| bool "open by fhandle syscalls" if EXPERT |
| select EXPORTFS |
| default y |
| help |
| If you say Y here, a user level program will be able to map |
| file names to handle and then later use the handle for |
| different file system operations. This is useful in implementing |
| userspace file servers, which now track files using handles instead |
| of names. The handle would remain the same even if file names |
| get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) |
| syscalls. |
| |
| config USELIB |
| bool "uselib syscall" |
| def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
| help |
| This option enables the uselib syscall, a system call used in the |
| dynamic linker from libc5 and earlier. glibc does not use this |
| system call. If you intend to run programs built on libc5 or |
| earlier, you may need to enable this syscall. Current systems |
| running glibc can safely disable this. |
| |
| 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). System call auditing is included |
| on architectures which support it. |
| |
| config HAVE_ARCH_AUDITSYSCALL |
| bool |
| |
| config AUDITSYSCALL |
| def_bool y |
| depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
| |
| config AUDIT_WATCH |
| def_bool y |
| depends on AUDITSYSCALL |
| select FSNOTIFY |
| |
| config AUDIT_TREE |
| def_bool y |
| depends on AUDITSYSCALL |
| select FSNOTIFY |
| |
| source "kernel/irq/Kconfig" |
| source "kernel/time/Kconfig" |
| |
| menu "CPU/Task time and stats accounting" |
| |
| config VIRT_CPU_ACCOUNTING |
| bool |
| |
| choice |
| prompt "Cputime accounting" |
| default TICK_CPU_ACCOUNTING if !PPC64 |
| default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
| |
| # Kind of a stub config for the pure tick based cputime accounting |
| config TICK_CPU_ACCOUNTING |
| bool "Simple tick based cputime accounting" |
| depends on !S390 && !NO_HZ_FULL |
| help |
| This is the basic tick based cputime accounting that maintains |
| statistics about user, system and idle time spent on per jiffies |
| granularity. |
| |
| If unsure, say Y. |
| |
| config VIRT_CPU_ACCOUNTING_NATIVE |
| bool "Deterministic task and CPU time accounting" |
| depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
| select VIRT_CPU_ACCOUNTING |
| help |
| Select this option to enable more accurate task and CPU time |
| accounting. This is done by reading a CPU counter on each |
| kernel entry and exit and on transitions within the kernel |
| between system, softirq and hardirq state, so there is a |
| small performance impact. In the case of s390 or IBM POWER > 5, |
| this also enables accounting of stolen time on logically-partitioned |
| systems. |
| |
| config VIRT_CPU_ACCOUNTING_GEN |
| bool "Full dynticks CPU time accounting" |
| depends on HAVE_CONTEXT_TRACKING |
| depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
| select VIRT_CPU_ACCOUNTING |
| select CONTEXT_TRACKING |
| help |
| Select this option to enable task and CPU time accounting on full |
| dynticks systems. This accounting is implemented by watching every |
| kernel-user boundaries using the context tracking subsystem. |
| The accounting is thus performed at the expense of some significant |
| overhead. |
| |
| For now this is only useful if you are working on the full |
| dynticks subsystem development. |
| |
| If unsure, say N. |
| |
| endchoice |
| |
| config IRQ_TIME_ACCOUNTING |
| bool "Fine granularity task level IRQ time accounting" |
| depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
| help |
| Select this option to enable fine granularity task irq time |
| accounting. This is done by reading a timestamp on each |
| transitions between softirq and hardirq state, so there can be a |
| small performance impact. |
| |
| If in doubt, say N here. |
| |
| config BSD_PROCESS_ACCT |
| bool "BSD Process Accounting" |
| depends on MULTIUSER |
| 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.gnu.org/software/acct/>. |
| |
| config TASKSTATS |
| bool "Export task/process statistics through netlink" |
| depends on NET |
| depends on MULTIUSER |
| 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" |
| depends on TASKSTATS |
| select SCHED_INFO |
| 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 TASK_XACCT |
| bool "Enable extended accounting over taskstats" |
| 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" |
| 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. |
| |
| endmenu # "CPU/Task time and stats accounting" |
| |
| menu "RCU Subsystem" |
| |
| config TREE_RCU |
| bool |
| default y if !PREEMPT && SMP |
| help |
| This option selects the RCU implementation that is |
| designed for very large SMP system with hundreds or |
| thousands of CPUs. It also scales down nicely to |
| smaller systems. |
| |
| config PREEMPT_RCU |
| bool |
| default y if PREEMPT |
| help |
| This option selects the RCU implementation that is |
| designed for very large SMP systems with hundreds or |
| thousands of CPUs, but for which real-time response |
| is also required. It also scales down nicely to |
| smaller systems. |
| |
| Select this option if you are unsure. |
| |
| config TINY_RCU |
| bool |
| default y if !PREEMPT && !SMP |
| help |
| This option selects the RCU implementation that is |
| designed for UP systems from which real-time response |
| is not required. This option greatly reduces the |
| memory footprint of RCU. |
| |
| config RCU_EXPERT |
| bool "Make expert-level adjustments to RCU configuration" |
| default n |
| help |
| This option needs to be enabled if you wish to make |
| expert-level adjustments to RCU configuration. By default, |
| no such adjustments can be made, which has the often-beneficial |
| side-effect of preventing "make oldconfig" from asking you all |
| sorts of detailed questions about how you would like numerous |
| obscure RCU options to be set up. |
| |
| Say Y if you need to make expert-level adjustments to RCU. |
| |
| Say N if you are unsure. |
| |
| config SRCU |
| bool |
| default y |
| help |
| This option selects the sleepable version of RCU. This version |
| permits arbitrary sleeping or blocking within RCU read-side critical |
| sections. |
| |
| config CLASSIC_SRCU |
| bool "Use v4.11 classic SRCU implementation" |
| default n |
| depends on RCU_EXPERT && SRCU |
| help |
| This option selects the traditional well-tested classic SRCU |
| implementation from v4.11, as might be desired for enterprise |
| Linux distributions. Without this option, the shiny new |
| Tiny SRCU and Tree SRCU implementations are used instead. |
| At some point, it is hoped that Tiny SRCU and Tree SRCU |
| will accumulate enough test time and confidence to allow |
| Classic SRCU to be dropped entirely. |
| |
| Say Y if you need a rock-solid SRCU. |
| |
| Say N if you would like help test Tree SRCU. |
| |
| config TINY_SRCU |
| bool |
| default y if SRCU && TINY_RCU && !CLASSIC_SRCU |
| help |
| This option selects the single-CPU non-preemptible version of SRCU. |
| |
| config TREE_SRCU |
| bool |
| default y if SRCU && !TINY_RCU && !CLASSIC_SRCU |
| help |
| This option selects the full-fledged version of SRCU. |
| |
| config TASKS_RCU |
| bool |
| default n |
| select SRCU |
| help |
| This option enables a task-based RCU implementation that uses |
| only voluntary context switch (not preemption!), idle, and |
| user-mode execution as quiescent states. |
| |
| config RCU_STALL_COMMON |
| def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE ) |
| help |
| This option enables RCU CPU stall code that is common between |
| the TINY and TREE variants of RCU. The purpose is to allow |
| the tiny variants to disable RCU CPU stall warnings, while |
| making these warnings mandatory for the tree variants. |
| |
| config RCU_NEED_SEGCBLIST |
| def_bool ( TREE_RCU || PREEMPT_RCU || TINY_SRCU || TREE_SRCU ) |
| |
| config CONTEXT_TRACKING |
| bool |
| |
| config CONTEXT_TRACKING_FORCE |
| bool "Force context tracking" |
| depends on CONTEXT_TRACKING |
| default y if !NO_HZ_FULL |
| help |
| The major pre-requirement for full dynticks to work is to |
| support the context tracking subsystem. But there are also |
| other dependencies to provide in order to make the full |
| dynticks working. |
| |
| This option stands for testing when an arch implements the |
| context tracking backend but doesn't yet fullfill all the |
| requirements to make the full dynticks feature working. |
| Without the full dynticks, there is no way to test the support |
| for context tracking and the subsystems that rely on it: RCU |
| userspace extended quiescent state and tickless cputime |
| accounting. This option copes with the absence of the full |
| dynticks subsystem by forcing the context tracking on all |
| CPUs in the system. |
| |
| Say Y only if you're working on the development of an |
| architecture backend for the context tracking. |
| |
| Say N otherwise, this option brings an overhead that you |
| don't want in production. |
| |
| |
| config RCU_FANOUT |
| int "Tree-based hierarchical RCU fanout value" |
| range 2 64 if 64BIT |
| range 2 32 if !64BIT |
| depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT |
| 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 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. |
| |
| config RCU_FANOUT_LEAF |
| int "Tree-based hierarchical RCU leaf-level fanout value" |
| range 2 64 if 64BIT |
| range 2 32 if !64BIT |
| depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT |
| default 16 |
| help |
| This option controls the leaf-level fanout of hierarchical |
| implementations of RCU, and allows trading off cache misses |
| against lock contention. Systems that synchronize their |
| scheduling-clock interrupts for energy-efficiency reasons will |
| want the default because the smaller leaf-level fanout keeps |
| lock contention levels acceptably low. Very large systems |
| (hundreds or thousands of CPUs) will instead want to set this |
| value to the maximum value possible in order to reduce the |
| number of cache misses incurred during RCU's grace-period |
| initialization. These systems tend to run CPU-bound, and thus |
| are not helped by synchronized interrupts, and thus tend to |
| skew them, which reduces lock contention enough that large |
| leaf-level fanouts work well. That said, setting leaf-level |
| fanout to a large number will likely cause problematic |
| lock contention on the leaf-level rcu_node structures unless |
| you boot with the skew_tick kernel parameter. |
| |
| Select a specific number if testing RCU itself. |
| |
| Select the maximum permissible value for large systems, but |
| please understand that you may also need to set the skew_tick |
| kernel boot parameter to avoid contention on the rcu_node |
| structure's locks. |
| |
| Take the default if unsure. |
| |
| config RCU_FAST_NO_HZ |
| bool "Accelerate last non-dyntick-idle CPU's grace periods" |
| depends on NO_HZ_COMMON && SMP && RCU_EXPERT |
| default n |
| help |
| This option permits CPUs to enter dynticks-idle state even if |
| they have RCU callbacks queued, and prevents RCU from waking |
| these CPUs up more than roughly once every four jiffies (by |
| default, you can adjust this using the rcutree.rcu_idle_gp_delay |
| parameter), thus improving energy efficiency. On the other |
| hand, this option increases the duration of RCU grace periods, |
| for example, slowing down synchronize_rcu(). |
| |
| Say Y if energy efficiency is critically important, and you |
| don't care about increased grace-period durations. |
| |
| Say N if you are unsure. |
| |
| config TREE_RCU_TRACE |
| def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU ) |
| select DEBUG_FS |
| help |
| This option provides tracing for the TREE_RCU and |
| PREEMPT_RCU implementations, permitting Makefile to |
| trivially select kernel/rcutree_trace.c. |
| |
| config RCU_BOOST |
| bool "Enable RCU priority boosting" |
| depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT |
| default n |
| help |
| This option boosts the priority of preempted RCU readers that |
| block the current preemptible RCU grace period for too long. |
| This option also prevents heavy loads from blocking RCU |
| callback invocation for all flavors of RCU. |
| |
| Say Y here if you are working with real-time apps or heavy loads |
| Say N here if you are unsure. |
| |
| config RCU_KTHREAD_PRIO |
| int "Real-time priority to use for RCU worker threads" |
| range 1 99 if RCU_BOOST |
| range 0 99 if !RCU_BOOST |
| default 1 if RCU_BOOST |
| default 0 if !RCU_BOOST |
| depends on RCU_EXPERT |
| help |
| This option specifies the SCHED_FIFO priority value that will be |
| assigned to the rcuc/n and rcub/n threads and is also the value |
| used for RCU_BOOST (if enabled). If you are working with a |
| real-time application that has one or more CPU-bound threads |
| running at a real-time priority level, you should set |
| RCU_KTHREAD_PRIO to a priority higher than the highest-priority |
| real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO |
| value of 1 is appropriate in the common case, which is real-time |
| applications that do not have any CPU-bound threads. |
| |
| Some real-time applications might not have a single real-time |
| thread that saturates a given CPU, but instead might have |
| multiple real-time threads that, taken together, fully utilize |
| that CPU. In this case, you should set RCU_KTHREAD_PRIO to |
| a priority higher than the lowest-priority thread that is |
| conspiring to prevent the CPU from running any non-real-time |
| tasks. For example, if one thread at priority 10 and another |
| thread at priority 5 are between themselves fully consuming |
| the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be |
| set to priority 6 or higher. |
| |
| Specify the real-time priority, or take the default if unsure. |
| |
| config RCU_BOOST_DELAY |
| int "Milliseconds to delay boosting after RCU grace-period start" |
| range 0 3000 |
| depends on RCU_BOOST |
| default 500 |
| help |
| This option specifies the time to wait after the beginning of |
| a given grace period before priority-boosting preempted RCU |
| readers blocking that grace period. Note that any RCU reader |
| blocking an expedited RCU grace period is boosted immediately. |
| |
| Accept the default if unsure. |
| |
| config RCU_NOCB_CPU |
| bool "Offload RCU callback processing from boot-selected CPUs" |
| depends on TREE_RCU || PREEMPT_RCU |
| depends on RCU_EXPERT || NO_HZ_FULL |
| default n |
| help |
| Use this option to reduce OS jitter for aggressive HPC or |
| real-time workloads. It can also be used to offload RCU |
| callback invocation to energy-efficient CPUs in battery-powered |
| asymmetric multiprocessors. |
| |
| This option offloads callback invocation from the set of |
| CPUs specified at boot time by the rcu_nocbs parameter. |
| For each such CPU, a kthread ("rcuox/N") will be created to |
| invoke callbacks, where the "N" is the CPU being offloaded, |
| and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and |
| "s" for RCU-sched. Nothing prevents this kthread from running |
| on the specified CPUs, but (1) the kthreads may be preempted |
| between each callback, and (2) affinity or cgroups can be used |
| to force the kthreads to run on whatever set of CPUs is desired. |
| |
| Say Y here if you want to help to debug reduced OS jitter. |
| Say N here if you are unsure. |
| |
| choice |
| prompt "Build-forced no-CBs CPUs" |
| default RCU_NOCB_CPU_NONE |
| depends on RCU_NOCB_CPU |
| help |
| This option allows no-CBs CPUs (whose RCU callbacks are invoked |
| from kthreads rather than from softirq context) to be specified |
| at build time. Additional no-CBs CPUs may be specified by |
| the rcu_nocbs= boot parameter. |
| |
| config RCU_NOCB_CPU_NONE |
| bool "No build_forced no-CBs CPUs" |
| help |
| This option does not force any of the CPUs to be no-CBs CPUs. |
| Only CPUs designated by the rcu_nocbs= boot parameter will be |
| no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU |
| kthreads whose names begin with "rcuo". All other CPUs will |
| invoke their own RCU callbacks in softirq context. |
| |
| Select this option if you want to choose no-CBs CPUs at |
| boot time, for example, to allow testing of different no-CBs |
| configurations without having to rebuild the kernel each time. |
| |
| config RCU_NOCB_CPU_ZERO |
| bool "CPU 0 is a build_forced no-CBs CPU" |
| help |
| This option forces CPU 0 to be a no-CBs CPU, so that its RCU |
| callbacks are invoked by a per-CPU kthread whose name begins |
| with "rcuo". Additional CPUs may be designated as no-CBs |
| CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs. |
| All other CPUs will invoke their own RCU callbacks in softirq |
| context. |
| |
| Select this if CPU 0 needs to be a no-CBs CPU for real-time |
| or energy-efficiency reasons, but the real reason it exists |
| is to ensure that randconfig testing covers mixed systems. |
| |
| config RCU_NOCB_CPU_ALL |
| bool "All CPUs are build_forced no-CBs CPUs" |
| help |
| This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs= |
| boot parameter will be ignored. All CPUs' RCU callbacks will |
| be executed in the context of per-CPU rcuo kthreads created for |
| this purpose. Assuming that the kthreads whose names start with |
| "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter |
| on the remaining CPUs, but might decrease memory locality during |
| RCU-callback invocation, thus potentially degrading throughput. |
| |
| Select this if all CPUs need to be no-CBs CPUs for real-time |
| or energy-efficiency reasons. |
| |
| endchoice |
| |
| endmenu # "RCU Subsystem" |
| |
| config BUILD_BIN2C |
| bool |
| default n |
| |
| config IKCONFIG |
| tristate "Kernel .config support" |
| select BUILD_BIN2C |
| ---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 LOG_BUF_SHIFT |
| int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" |
| range 12 25 |
| default 17 |
| depends on PRINTK |
| help |
| Select the minimal kernel log buffer size as a power of 2. |
| The final size is affected by LOG_CPU_MAX_BUF_SHIFT config |
| parameter, see below. Any higher size also might be forced |
| by "log_buf_len" boot parameter. |
| |
| Examples: |
| 17 => 128 KB |
| 16 => 64 KB |
| 15 => 32 KB |
| 14 => 16 KB |
| 13 => 8 KB |
| 12 => 4 KB |
| |
| config LOG_CPU_MAX_BUF_SHIFT |
| int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" |
| depends on SMP |
| range 0 21 |
| default 12 if !BASE_SMALL |
| default 0 if BASE_SMALL |
| depends on PRINTK |
| help |
| This option allows to increase the default ring buffer size |
| according to the number of CPUs. The value defines the contribution |
| of each CPU as a power of 2. The used space is typically only few |
| lines however it might be much more when problems are reported, |
| e.g. backtraces. |
| |
| The increased size means that a new buffer has to be allocated and |
| the original static one is unused. It makes sense only on systems |
| with more CPUs. Therefore this value is used only when the sum of |
| contributions is greater than the half of the default kernel ring |
| buffer as defined by LOG_BUF_SHIFT. The default values are set |
| so that more than 64 CPUs are needed to trigger the allocation. |
| |
| Also this option is ignored when "log_buf_len" kernel parameter is |
| used as it forces an exact (power of two) size of the ring buffer. |
| |
| The number of possible CPUs is used for this computation ignoring |
| hotplugging making the computation optimal for the worst case |
| scenario while allowing a simple algorithm to be used from bootup. |
| |
| Examples shift values and their meaning: |
| 17 => 128 KB for each CPU |
| 16 => 64 KB for each CPU |
| 15 => 32 KB for each CPU |
| 14 => 16 KB for each CPU |
| 13 => 8 KB for each CPU |
| 12 => 4 KB for each CPU |
| |
| config PRINTK_SAFE_LOG_BUF_SHIFT |
| int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" |
| range 10 21 |
| default 13 |
| depends on PRINTK |
| help |
| Select the size of an alternate printk per-CPU buffer where messages |
| printed from usafe contexts are temporary stored. One example would |
| be NMI messages, another one - printk recursion. The messages are |
| copied to the main log buffer in a safe context to avoid a deadlock. |
| The value defines the size as a power of 2. |
| |
| Those messages are rare and limited. The largest one is when |
| a backtrace is printed. It usually fits into 4KB. Select |
| 8KB if you want to be on the safe side. |
| |
| Examples: |
| 17 => 128 KB for each CPU |
| 16 => 64 KB for each CPU |
| 15 => 32 KB for each CPU |
| 14 => 16 KB for each CPU |
| 13 => 8 KB for each CPU |
| 12 => 4 KB for each CPU |
| |
| # |
| # Architectures with an unreliable sched_clock() should select this: |
| # |
| config HAVE_UNSTABLE_SCHED_CLOCK |
| bool |
| |
| config GENERIC_SCHED_CLOCK |
| bool |
| |
| # |
| # For architectures that want to enable the support for NUMA-affine scheduler |
| # balancing logic: |
| # |
| config ARCH_SUPPORTS_NUMA_BALANCING |
| bool |
| |
| # |
| # For architectures that prefer to flush all TLBs after a number of pages |
| # are unmapped instead of sending one IPI per page to flush. The architecture |
| # must provide guarantees on what happens if a clean TLB cache entry is |
| # written after the unmap. Details are in mm/rmap.c near the check for |
| # should_defer_flush. The architecture should also consider if the full flush |
| # and the refill costs are offset by the savings of sending fewer IPIs. |
| config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH |
| bool |
| |
| # |
| # For architectures that know their GCC __int128 support is sound |
| # |
| config ARCH_SUPPORTS_INT128 |
| bool |
| |
| # For architectures that (ab)use NUMA to represent different memory regions |
| # all cpu-local but of different latencies, such as SuperH. |
| # |
| config ARCH_WANT_NUMA_VARIABLE_LOCALITY |
| bool |
| |
| config NUMA_BALANCING |
| bool "Memory placement aware NUMA scheduler" |
| depends on ARCH_SUPPORTS_NUMA_BALANCING |
| depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY |
| depends on SMP && NUMA && MIGRATION |
| help |
| This option adds support for automatic NUMA aware memory/task placement. |
| The mechanism is quite primitive and is based on migrating memory when |
| it has references to the node the task is running on. |
| |
| This system will be inactive on UMA systems. |
| |
| config NUMA_BALANCING_DEFAULT_ENABLED |
| bool "Automatically enable NUMA aware memory/task placement" |
| default y |
| depends on NUMA_BALANCING |
| help |
| If set, automatic NUMA balancing will be enabled if running on a NUMA |
| machine. |
| |
| menuconfig CGROUPS |
| bool "Control Group support" |
| select KERNFS |
| 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/cgroup-v1/ (features for grouping, isolation |
| and resource control) |
| |
| Say N if unsure. |
| |
| if CGROUPS |
| |
| config PAGE_COUNTER |
| bool |
| |
| config MEMCG |
| bool "Memory controller" |
| select PAGE_COUNTER |
| select EVENTFD |
| help |
| Provides control over the memory footprint of tasks in a cgroup. |
| |
| config MEMCG_SWAP |
| bool "Swap controller" |
| depends on MEMCG && SWAP |
| help |
| Provides control over the swap space consumed by tasks in a cgroup. |
| |
| config MEMCG_SWAP_ENABLED |
| bool "Swap controller enabled by default" |
| depends on MEMCG_SWAP |
| default y |
| help |
| Memory Resource Controller Swap Extension comes with its price in |
| a bigger memory consumption. General purpose distribution kernels |
| which want to enable the feature but keep it disabled by default |
| and let the user enable it by swapaccount=1 boot command line |
| parameter should have this option unselected. |
| For those who want to have the feature enabled by default should |
| select this option (if, for some reason, they need to disable it |
| then swapaccount=0 does the trick). |
| |
| config BLK_CGROUP |
| bool "IO controller" |
| depends on BLOCK |
| default n |
| ---help--- |
| Generic block IO controller cgroup interface. This is the common |
| cgroup interface which should be used by various IO controlling |
| policies. |
| |
| Currently, CFQ IO scheduler uses it to recognize task groups and |
| control disk bandwidth allocation (proportional time slice allocation) |
| to such task groups. It is also used by bio throttling logic in |
| block layer to implement upper limit in IO rates on a device. |
| |
| This option only enables generic Block IO controller infrastructure. |
| One needs to also enable actual IO controlling logic/policy. For |
| enabling proportional weight division of disk bandwidth in CFQ, set |
| CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set |
| CONFIG_BLK_DEV_THROTTLING=y. |
| |
| See Documentation/cgroup-v1/blkio-controller.txt for more information. |
| |
| config DEBUG_BLK_CGROUP |
| bool "IO controller debugging" |
| depends on BLK_CGROUP |
| default n |
| ---help--- |
| Enable some debugging help. Currently it exports additional stat |
| files in a cgroup which can be useful for debugging. |
| |
| config CGROUP_WRITEBACK |
| bool |
| depends on MEMCG && BLK_CGROUP |
| default y |
| |
| menuconfig CGROUP_SCHED |
| bool "CPU controller" |
| default n |
| help |
| This feature lets CPU scheduler recognize task groups and control CPU |
| bandwidth allocation to such task groups. It uses cgroups to group |
| tasks. |
| |
| if CGROUP_SCHED |
| config FAIR_GROUP_SCHED |
| bool "Group scheduling for SCHED_OTHER" |
| depends on CGROUP_SCHED |
| default CGROUP_SCHED |
| |
| config CFS_BANDWIDTH |
| bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" |
| depends on FAIR_GROUP_SCHED |
| default n |
| help |
| This option allows users to define CPU bandwidth rates (limits) for |
| tasks running within the fair group scheduler. Groups with no limit |
| set are considered to be unconstrained and will run with no |
| restriction. |
| See tip/Documentation/scheduler/sched-bwc.txt for more information. |
| |
| config RT_GROUP_SCHED |
| bool "Group scheduling for SCHED_RR/FIFO" |
| depends on CGROUP_SCHED |
| default n |
| help |
| This feature lets you explicitly allocate real CPU bandwidth |
| to task groups. 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. |
| |
| endif #CGROUP_SCHED |
| |
| config CGROUP_PIDS |
| bool "PIDs controller" |
| help |
| Provides enforcement of process number limits in the scope of a |
| cgroup. Any attempt to fork more processes than is allowed in the |
| cgroup will fail. PIDs are fundamentally a global resource because it |
| is fairly trivial to reach PID exhaustion before you reach even a |
| conservative kmemcg limit. As a result, it is possible to grind a |
| system to halt without being limited by other cgroup policies. The |
| PIDs controller is designed to stop this from happening. |
| |
| It should be noted that organisational operations (such as attaching |
| to a cgroup hierarchy will *not* be blocked by the PIDs controller), |
| since the PIDs limit only affects a process's ability to fork, not to |
| attach to a cgroup. |
| |
| config CGROUP_RDMA |
| bool "RDMA controller" |
| help |
| Provides enforcement of RDMA resources defined by IB stack. |
| It is fairly easy for consumers to exhaust RDMA resources, which |
| can result into resource unavailability to other consumers. |
| RDMA controller is designed to stop this from happening. |
| Attaching processes with active RDMA resources to the cgroup |
| hierarchy is allowed even if can cross the hierarchy's limit. |
| |
| config CGROUP_FREEZER |
| bool "Freezer controller" |
| help |
| Provides a way to freeze and unfreeze all tasks in a |
| cgroup. |
| |
| This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
| controller includes important in-kernel memory consumers per default. |
| |
| If you're using cgroup2, say N. |
| |
| config CGROUP_HUGETLB |
| bool "HugeTLB controller" |
| depends on HUGETLB_PAGE |
| select PAGE_COUNTER |
| default n |
| help |
| Provides a cgroup controller for HugeTLB pages. |
| When you enable this, you can put a per cgroup limit on HugeTLB usage. |
| The limit is enforced during page fault. Since HugeTLB doesn't |
| support page reclaim, enforcing the limit at page fault time implies |
| that, the application will get SIGBUS signal if it tries to access |
| HugeTLB pages beyond its limit. This requires the application to know |
| beforehand how much HugeTLB pages it would require for its use. The |
| control group is tracked in the third page lru pointer. This means |
| that we cannot use the controller with huge page less than 3 pages. |
| |
| config CPUSETS |
| bool "Cpuset controller" |
| 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 PROC_PID_CPUSET |
| bool "Include legacy /proc/<pid>/cpuset file" |
| depends on CPUSETS |
| default y |
| |
| config CGROUP_DEVICE |
| bool "Device controller" |
| help |
| Provides a cgroup controller implementing whitelists for |
| devices which a process in the cgroup can mknod or open. |
| |
| config CGROUP_CPUACCT |
| bool "Simple CPU accounting controller" |
| help |
| Provides a simple controller for monitoring the |
| total CPU consumed by the tasks in a cgroup. |
| |
| config CGROUP_PERF |
| bool "Perf controller" |
| depends on PERF_EVENTS |
| help |
| This option extends the perf per-cpu mode to restrict monitoring |
| to threads which belong to the cgroup specified and run on the |
| designated cpu. |
| |
| Say N if unsure. |
| |
| config CGROUP_BPF |
| bool "Support for eBPF programs attached to cgroups" |
| depends on BPF_SYSCALL |
| select SOCK_CGROUP_DATA |
| help |
| Allow attaching eBPF programs to a cgroup using the bpf(2) |
| syscall command BPF_PROG_ATTACH. |
| |
| In which context these programs are accessed depends on the type |
| of attachment. For instance, programs that are attached using |
| BPF_CGROUP_INET_INGRESS will be executed on the ingress path of |
| inet sockets. |
| |
| config CGROUP_DEBUG |
| bool "Example controller" |
| default n |
| help |
| This option enables a simple controller that exports |
| debugging information about the cgroups framework. |
| |
| Say N. |
| |
| config SOCK_CGROUP_DATA |
| bool |
| default n |
| |
| endif # CGROUPS |
| |
| config CHECKPOINT_RESTORE |
| bool "Checkpoint/restore support" if EXPERT |
| select PROC_CHILDREN |
| default n |
| help |
| Enables additional kernel features in a sake of checkpoint/restore. |
| In particular it adds auxiliary prctl codes to setup process text, |
| data and heap segment sizes, and a few additional /proc filesystem |
| entries. |
| |
| If unsure, say N here. |
| |
| menuconfig NAMESPACES |
| bool "Namespaces support" if EXPERT |
| depends on MULTIUSER |
| default !EXPERT |
| 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. |
| |
| if NAMESPACES |
| |
| config UTS_NS |
| bool "UTS namespace" |
| default y |
| help |
| In this namespace tasks see different info provided with the |
| uname() system call |
| |
| config IPC_NS |
| bool "IPC namespace" |
| depends on (SYSVIPC || POSIX_MQUEUE) |
| default y |
| help |
| In this namespace tasks work with IPC ids which correspond to |
| different IPC objects in different namespaces. |
| |
| config USER_NS |
| bool "User namespace" |
| default n |
| help |
| This allows containers, i.e. vservers, to use user namespaces |
| to provide different user info for different servers. |
| |
| When user namespaces are enabled in the kernel it is |
| recommended that the MEMCG option also be enabled and that |
| user-space use the memory control groups to limit the amount |
| of memory a memory unprivileged users can use. |
| |
| If unsure, say N. |
| |
| config PID_NS |
| bool "PID Namespaces" |
| default y |
| help |
| Support process id namespaces. This allows having multiple |
| processes with the same pid as long as they are in different |
| pid namespaces. This is a building block of containers. |
| |
| config NET_NS |
| bool "Network namespace" |
| depends on NET |
| default y |
| help |
| Allow user space to create what appear to be multiple instances |
| of the network stack. |
| |
| endif # NAMESPACES |
| |
| config SCHED_AUTOGROUP |
| bool "Automatic process group scheduling" |
| select CGROUPS |
| select CGROUP_SCHED |
| select FAIR_GROUP_SCHED |
| help |
| This option optimizes the scheduler for common desktop workloads by |
| automatically creating and populating task groups. This separation |
| of workloads isolates aggressive CPU burners (like build jobs) from |
| desktop applications. Task group autogeneration is currently based |
| upon task session. |
| |
| config SYSFS_DEPRECATED |
| bool "Enable deprecated sysfs features to support old userspace tools" |
| depends on SYSFS |
| default n |
| help |
| This option adds code that switches the layout of the "block" class |
| devices, to not show up in /sys/class/block/, but only in |
| /sys/block/. |
| |
| This switch is only active when the sysfs.deprecated=1 boot option is |
| passed or the SYSFS_DEPRECATED_V2 option is set. |
| |
| 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. |
| |
| config SYSFS_DEPRECATED_V2 |
| bool "Enable deprecated sysfs features by default" |
| default n |
| depends on SYSFS |
| depends on SYSFS_DEPRECATED |
| help |
| Enable deprecated sysfs by default. |
| |
| See the CONFIG_SYSFS_DEPRECATED option for more details about this |
| option. |
| |
| Only if you are using a new kernel on an old distribution, you might |
| need to say Y here. Even then, odds are you would not need it |
| enabled, you can always pass the boot option if absolutely necessary. |
| |
| config RELAY |
| bool "Kernel->user space relay support (formerly relayfs)" |
| select IRQ_WORK |
| 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. |
| |
| config BLK_DEV_INITRD |
| bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" |
| depends on BROKEN || !FRV |
| help |
| The initial RAM filesystem is a ramfs which is loaded by the |
| boot loader (loadlin or lilo) and that is mounted as root |
| before the normal boot procedure. It is typically used to |
| load modules needed to mount the "real" root file system, |
| etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
| |
| If RAM disk support (BLK_DEV_RAM) is also included, this |
| also enables initial RAM disk (initrd) support and adds |
| 15 Kbytes (more on some other architectures) to the kernel size. |
| |
| If unsure say Y. |
| |
| if BLK_DEV_INITRD |
| |
| source "usr/Kconfig" |
| |
| endif |
| |
| choice |
| prompt "Compiler optimization level" |
| default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE |
| |
| config CC_OPTIMIZE_FOR_PERFORMANCE |
| bool "Optimize for performance" |
| help |
| This is the default optimization level for the kernel, building |
| with the "-O2" compiler flag for best performance and most |
| helpful compile-time warnings. |
| |
| config CC_OPTIMIZE_FOR_SIZE |
| bool "Optimize for size" |
| help |
| Enabling this option will pass "-Os" instead of "-O2" to |
| your compiler resulting in a smaller kernel. |
| |
| If unsure, say N. |
| |
| endchoice |
| |
| config SYSCTL |
| bool |
| |
| config ANON_INODES |
| bool |
| |
| config HAVE_UID16 |
| bool |
| |
| config SYSCTL_EXCEPTION_TRACE |
| bool |
| help |
| Enable support for /proc/sys/debug/exception-trace. |
| |
| config SYSCTL_ARCH_UNALIGN_NO_WARN |
| bool |
| help |
| Enable support for /proc/sys/kernel/ignore-unaligned-usertrap |
| Allows arch to define/use @no_unaligned_warning to possibly warn |
| about unaligned access emulation going on under the hood. |
| |
| config SYSCTL_ARCH_UNALIGN_ALLOW |
| bool |
| help |
| Enable support for /proc/sys/kernel/unaligned-trap |
| Allows arches to define/use @unaligned_enabled to runtime toggle |
| the unaligned access emulation. |
| see arch/parisc/kernel/unaligned.c for reference |
| |
| config HAVE_PCSPKR_PLATFORM |
| bool |
| |
| # interpreter that classic socket filters depend on |
| config BPF |
| bool |
| |
| menuconfig EXPERT |
| bool "Configure standard kernel features (expert users)" |
| # Unhide debug options, to make the on-by-default options visible |
| select DEBUG_KERNEL |
| 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 EXPERT |
| depends on HAVE_UID16 && MULTIUSER |
| default y |
| help |
| This enables the legacy 16-bit UID syscall wrappers. |
| |
| config MULTIUSER |
| bool "Multiple users, groups and capabilities support" if EXPERT |
| default y |
| help |
| This option enables support for non-root users, groups and |
| capabilities. |
| |
| If you say N here, all processes will run with UID 0, GID 0, and all |
| possible capabilities. Saying N here also compiles out support for |
| system calls related to UIDs, GIDs, and capabilities, such as setuid, |
| setgid, and capset. |
| |
| If unsure, say Y here. |
| |
| config SGETMASK_SYSCALL |
| bool "sgetmask/ssetmask syscalls support" if EXPERT |
| def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH |
| ---help--- |
| sys_sgetmask and sys_ssetmask are obsolete system calls |
| no longer supported in libc but still enabled by default in some |
| architectures. |
| |
| If unsure, leave the default option here. |
| |
| config SYSFS_SYSCALL |
| bool "Sysfs syscall support" if EXPERT |
| default y |
| ---help--- |
| sys_sysfs is an obsolete system call no longer supported in libc. |
| Note that disabling this option is more secure but might break |
| compatibility with some systems. |
| |
| If unsure say Y here. |
| |
| config SYSCTL_SYSCALL |
| bool "Sysctl syscall support" if EXPERT |
| depends on PROC_SYSCTL |
| default n |
| 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 N here. |
| |
| config POSIX_TIMERS |
| bool "Posix Clocks & timers" if EXPERT |
| default y |
| help |
| This includes native support for POSIX timers to the kernel. |
| Some embedded systems have no use for them and therefore they |
| can be configured out to reduce the size of the kernel image. |
| |
| When this option is disabled, the following syscalls won't be |
| available: timer_create, timer_gettime: timer_getoverrun, |
| timer_settime, timer_delete, clock_adjtime, getitimer, |
| setitimer, alarm. Furthermore, the clock_settime, clock_gettime, |
| clock_getres and clock_nanosleep syscalls will be limited to |
| CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. |
| |
| If unsure say y. |
| |
| config KALLSYMS |
| bool "Load all symbols for debugging/ksymoops" if EXPERT |
| 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 and backtraces (i.e., symbols from the text and inittext |
| sections). This is sufficient for most cases. And only in very rare |
| cases (e.g., when a debugger is used) all symbols are required (e.g., |
| names of variables from the data sections, etc). |
| |
| This option makes sure that all symbols are loaded into the kernel |
| image (i.e., symbols from all sections) in cost of increased kernel |
| size (depending on the kernel configuration, it may be 300KiB or |
| something like this). |
| |
| Say N unless you really need all symbols. |
| |
| config KALLSYMS_ABSOLUTE_PERCPU |
| bool |
| depends on KALLSYMS |
| default X86_64 && SMP |
| |
| config KALLSYMS_BASE_RELATIVE |
| bool |
| depends on KALLSYMS |
| default !IA64 && !(TILE && 64BIT) |
| help |
| Instead of emitting them as absolute values in the native word size, |
| emit the symbol references in the kallsyms table as 32-bit entries, |
| each containing a relative value in the range [base, base + U32_MAX] |
| or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either |
| an absolute value in the range [0, S32_MAX] or a relative value in the |
| range [base, base + S32_MAX], where base is the lowest relative symbol |
| address encountered in the image. |
| |
| On 64-bit builds, this reduces the size of the address table by 50%, |
| but more importantly, it results in entries whose values are build |
| time constants, and no relocation pass is required at runtime to fix |
| up the entries based on the runtime load address of the kernel. |
| |
| config PRINTK |
| default y |
| bool "Enable support for printk" if EXPERT |
| select IRQ_WORK |
| 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 PRINTK_NMI |
| def_bool y |
| depends on PRINTK |
| depends on HAVE_NMI |
| |
| config BUG |
| bool "BUG() support" if EXPERT |
| 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 |
| depends on COREDUMP |
| default y |
| bool "Enable ELF core dumps" if EXPERT |
| help |
| Enable support for generating core dumps. Disabling saves about 4k. |
| |
| |
| config PCSPKR_PLATFORM |
| bool "Enable PC-Speaker support" if EXPERT |
| depends on HAVE_PCSPKR_PLATFORM |
| select I8253_LOCK |
| default y |
| help |
| This option allows to disable the internal PC-Speaker |
| support, saving some memory. |
| |
| config BASE_FULL |
| default y |
| bool "Enable full-sized data structures for core" if EXPERT |
| 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 EXPERT |
| 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 HAVE_FUTEX_CMPXCHG |
| bool |
| depends on FUTEX |
| help |
| Architectures should select this if futex_atomic_cmpxchg_inatomic() |
| is implemented and always working. This removes a couple of runtime |
| checks. |
| |
| config EPOLL |
| bool "Enable eventpoll support" if EXPERT |
| default y |
| select ANON_INODES |
| help |
| Disabling this option will cause the kernel to be built without |
| support for epoll family of system calls. |
| |
| config SIGNALFD |
| bool "Enable signalfd() system call" if EXPERT |
| select ANON_INODES |
| default y |
| help |
| Enable the signalfd() system call that allows to receive signals |
| on a file descriptor. |
| |
| If unsure, say Y. |
| |
| config TIMERFD |
| bool "Enable timerfd() system call" if EXPERT |
| select ANON_INODES |
| default y |
| help |
| Enable the timerfd() system call that allows to receive timer |
| events on a file descriptor. |
| |
| If unsure, say Y. |
| |
| config EVENTFD |
| bool "Enable eventfd() system call" if EXPERT |
| select ANON_INODES |
| default y |
| help |
| Enable the eventfd() system call that allows to receive both |
| kernel notification (ie. KAIO) or userspace notifications. |
| |
| If unsure, say Y. |
| |
| # syscall, maps, verifier |
| config BPF_SYSCALL |
| bool "Enable bpf() system call" |
| select ANON_INODES |
| select BPF |
| default n |
| help |
| Enable the bpf() system call that allows to manipulate eBPF |
| programs and maps via file descriptors. |
| |
| config SHMEM |
| bool "Use full shmem filesystem" if EXPERT |
| 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 AIO |
| bool "Enable AIO support" if EXPERT |
| 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 ADVISE_SYSCALLS |
| bool "Enable madvise/fadvise syscalls" if EXPERT |
| default y |
| help |
| This option enables the madvise and fadvise syscalls, used by |
| applications to advise the kernel about their future memory or file |
| usage, improving performance. If building an embedded system where no |
| applications use these syscalls, you can disable this option to save |
| space. |
| |
| config USERFAULTFD |
| bool "Enable userfaultfd() system call" |
| select ANON_INODES |
| depends on MMU |
| help |
| Enable the userfaultfd() system call that allows to intercept and |
| handle page faults in userland. |
| |
| config PCI_QUIRKS |
| default y |
| bool "Enable PCI quirk workarounds" if EXPERT |
| 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 MEMBARRIER |
| bool "Enable membarrier() system call" if EXPERT |
| default y |
| help |
| Enable the membarrier() system call that allows issuing memory |
| barriers across all running threads, which can be used to distribute |
| the cost of user-space memory barriers asymmetrically by transforming |
| pairs of memory barriers into pairs consisting of membarrier() and a |
| compiler barrier. |
| |
| If unsure, say Y. |
| |
| config EMBEDDED |
| bool "Embedded system" |
| option allnoconfig_y |
| select EXPERT |
| help |
| This option should be enabled if compiling the kernel for |
| an embedded system so certain expert options are available |
| for configuration. |
| |
| config HAVE_PERF_EVENTS |
| bool |
| help |
| See tools/perf/design.txt for details. |
| |
| config PERF_USE_VMALLOC |
| bool |
| help |
| See tools/perf/design.txt for details |
| |
| config PC104 |
| bool "PC/104 support" |
| help |
| Expose PC/104 form factor device drivers and options available for |
| selection and configuration. Enable this option if your target |
| machine has a PC/104 bus. |
| |
| menu "Kernel Performance Events And Counters" |
| |
| config PERF_EVENTS |
| bool "Kernel performance events and counters" |
| default y if PROFILING |
| depends on HAVE_PERF_EVENTS |
| select ANON_INODES |
| select IRQ_WORK |
| select SRCU |
| help |
| Enable kernel support for various performance events provided |
| by software and hardware. |
| |
| Software events are supported either built-in or via the |
| use of generic tracepoints. |
| |
| Most modern CPUs support performance events via performance |
| counter registers. These registers count the number of certain |
| types of hw events: such as instructions executed, cachemisses |
| suffered, or branches mis-predicted - without slowing down the |
| kernel or applications. These registers can also trigger interrupts |
| when a threshold number of events have passed - and can thus be |
| used to profile the code that runs on that CPU. |
| |
| The Linux Performance Event subsystem provides an abstraction of |
| these software and hardware event capabilities, available via a |
| system call and used by the "perf" utility in tools/perf/. It |
| provides per task and per CPU counters, and it provides event |
| capabilities on top of those. |
| |
| Say Y if unsure. |
| |
| config DEBUG_PERF_USE_VMALLOC |
| default n |
| bool "Debug: use vmalloc to back perf mmap() buffers" |
| depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
| select PERF_USE_VMALLOC |
| help |
| Use vmalloc memory to back perf mmap() buffers. |
| |
| Mostly useful for debugging the vmalloc code on platforms |
| that don't require it. |
| |
| Say N if unsure. |
| |
| endmenu |
| |
| config VM_EVENT_COUNTERS |
| default y |
| bool "Enable VM event counters for /proc/vmstat" if EXPERT |
| help |
| VM event counters are needed for event counts to be shown. |
| This option allows the disabling of the VM event counters |
| on EXPERT systems. /proc/vmstat will only show page counts |
| if VM event counters are disabled. |
| |
| config SLUB_DEBUG |
| default y |
| bool "Enable SLUB debugging support" if EXPERT |
| 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 SLUB_MEMCG_SYSFS_ON |
| default n |
| bool "Enable memcg SLUB sysfs support by default" if EXPERT |
| depends on SLUB && SYSFS && MEMCG |
| help |
| SLUB creates a directory under /sys/kernel/slab for each |
| allocation cache to host info and debug files. If memory |
| cgroup is enabled, each cache can have per memory cgroup |
| caches. SLUB can create the same sysfs directories for these |
| caches under /sys/kernel/slab/CACHE/cgroup but it can lead |
| to a very high number of debug files being created. This is |
| controlled by slub_memcg_sysfs boot parameter and this |
| config option determines the parameter's default value. |
| |
| 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 overridden at 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 |
| This option allows to select a slab allocator. |
| |
| config SLAB |
| bool "SLAB" |
| select HAVE_HARDENED_USERCOPY_ALLOCATOR |
| 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. |
| |
| config SLUB |
| bool "SLUB (Unqueued Allocator)" |
| select HAVE_HARDENED_USERCOPY_ALLOCATOR |
| help |
| SLUB is a slab allocator that minimizes cache line usage |
| 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. SLUB is the default choice for |
| a slab allocator. |
| |
| config SLOB |
| depends on EXPERT |
| bool "SLOB (Simple Allocator)" |
| help |
| SLOB replaces the stock allocator with a drastically simpler |
| allocator. SLOB is generally more space efficient but |
| does not perform as well on large systems. |
| |
| endchoice |
| |
| config SLAB_FREELIST_RANDOM |
| default n |
| depends on SLAB || SLUB |
| bool "SLAB freelist randomization" |
| help |
| Randomizes the freelist order used on creating new pages. This |
| security feature reduces the predictability of the kernel slab |
| allocator against heap overflows. |
| |
| config SLUB_CPU_PARTIAL |
| default y |
| depends on SLUB && SMP |
| bool "SLUB per cpu partial cache" |
| help |
| Per cpu partial caches accellerate objects allocation and freeing |
| that is local to a processor at the price of more indeterminism |
| in the latency of the free. On overflow these caches will be cleared |
| which requires the taking of locks that may cause latency spikes. |
| Typically one would choose no for a realtime system. |
| |
| config MMAP_ALLOW_UNINITIALIZED |
| bool "Allow mmapped anonymous memory to be uninitialized" |
| depends on EXPERT && !MMU |
| default n |
| help |
| Normally, and according to the Linux spec, anonymous memory obtained |
| from mmap() has it's contents cleared before it is passed to |
| userspace. Enabling this config option allows you to request that |
| mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus |
| providing a huge performance boost. If this option is not enabled, |
| then the flag will be ignored. |
| |
| This is taken advantage of by uClibc's malloc(), and also by |
| ELF-FDPIC binfmt's brk and stack allocator. |
| |
| Because of the obvious security issues, this option should only be |
| enabled on embedded devices where you control what is run in |
| userspace. Since that isn't generally a problem on no-MMU systems, |
| it is normally safe to say Y here. |
| |
| See Documentation/nommu-mmap.txt for more information. |
| |
| config SYSTEM_DATA_VERIFICATION |
| def_bool n |
| select SYSTEM_TRUSTED_KEYRING |
| select KEYS |
| select CRYPTO |
| select CRYPTO_RSA |
| select ASYMMETRIC_KEY_TYPE |
| select ASYMMETRIC_PUBLIC_KEY_SUBTYPE |
| select ASN1 |
| select OID_REGISTRY |
| select X509_CERTIFICATE_PARSER |
| select PKCS7_MESSAGE_PARSER |
| help |
| Provide PKCS#7 message verification using the contents of the system |
| trusted keyring to provide public keys. This then can be used for |
| module verification, kexec image verification and firmware blob |
| verification. |
| |
| config PROFILING |
| bool "Profiling support" |
| help |
| 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 |
| |
| source "arch/Kconfig" |
| |
| endmenu # General setup |
| |
| config HAVE_GENERIC_DMA_COHERENT |
| bool |
| default n |
| |
| config SLABINFO |
| bool |
| depends on PROC_FS |
| depends on SLAB || SLUB_DEBUG |
| default y |
| |
| config RT_MUTEXES |
| bool |
| |
| config BASE_SMALL |
| int |
| default 0 if BASE_FULL |
| default 1 if !BASE_FULL |
| |
| menuconfig MODULES |
| bool "Enable loadable module support" |
| option modules |
| 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. |
| |
| 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" |
| 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 smaller, faster |
| and simpler. If unsure, say Y. |
| |
| config MODULE_FORCE_UNLOAD |
| bool "Forced module unloading" |
| depends on MODULE_UNLOAD |
| 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" |
| 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_REL_CRCS |
| bool |
| depends on MODVERSIONS |
| |
| config MODULE_SRCVERSION_ALL |
| bool "Source checksum for all 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" |
| depends on MODULES |
| select SYSTEM_DATA_VERIFICATION |
| help |
| Check modules for valid signatures upon load: the signature |
| is simply appended to the module. For more information see |
| Documentation/module-signing.txt. |
| |
| Note that this option adds the OpenSSL development packages as a |
| kernel build dependency so that the signing tool can use its crypto |
| library. |
| |
| !!!WARNING!!! If you enable this option, you MUST make sure that the |
| module DOES NOT get stripped after being signed. This includes the |
| debuginfo strip done by some packagers (such as rpmbuild) and |
| inclusion into an initramfs that wants the module size reduced. |
| |
| config MODULE_SIG_FORCE |
| bool "Require modules to be validly signed" |
| depends on MODULE_SIG |
| help |
| Reject unsigned modules or signed modules for which we don't have a |
| key. Without this, such modules will simply taint the kernel. |
| |
| config MODULE_SIG_ALL |
| bool "Automatically sign all modules" |
| default y |
| depends on MODULE_SIG |
| help |
| Sign all modules during make modules_install. Without this option, |
| modules must be signed manually, using the scripts/sign-file tool. |
| |
| comment "Do not forget to sign required modules with scripts/sign-file" |
| depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL |
| |
| choice |
| prompt "Which hash algorithm should modules be signed with?" |
| depends on MODULE_SIG |
| help |
| This determines which sort of hashing algorithm will be used during |
| signature generation. This algorithm _must_ be built into the kernel |
| directly so that signature verification can take place. It is not |
| possible to load a signed module containing the algorithm to check |
| the signature on that module. |
| |
| config MODULE_SIG_SHA1 |
| bool "Sign modules with SHA-1" |
| select CRYPTO_SHA1 |
| |
| config MODULE_SIG_SHA224 |
| bool "Sign modules with SHA-224" |
| select CRYPTO_SHA256 |
| |
| config MODULE_SIG_SHA256 |
| bool "Sign modules with SHA-256" |
| select CRYPTO_SHA256 |
| |
| config MODULE_SIG_SHA384 |
| bool "Sign modules with SHA-384" |
| select CRYPTO_SHA512 |
| |
| config MODULE_SIG_SHA512 |
| bool "Sign modules with SHA-512" |
| select CRYPTO_SHA512 |
| |
| endchoice |
| |
| config MODULE_SIG_HASH |
| string |
| depends on MODULE_SIG |
| default "sha1" if MODULE_SIG_SHA1 |
| default "sha224" if MODULE_SIG_SHA224 |
| default "sha256" if MODULE_SIG_SHA256 |
| default "sha384" if MODULE_SIG_SHA384 |
| default "sha512" if MODULE_SIG_SHA512 |
| |
| config MODULE_COMPRESS |
| bool "Compress modules on installation" |
| depends on MODULES |
| help |
| |
| Compresses kernel modules when 'make modules_install' is run; gzip or |
| xz depending on "Compression algorithm" below. |
| |
| module-init-tools MAY support gzip, and kmod MAY support gzip and xz. |
| |
| Out-of-tree kernel modules installed using Kbuild will also be |
| compressed upon installation. |
| |
| Note: for modules inside an initrd or initramfs, it's more efficient |
| to compress the whole initrd or initramfs instead. |
| |
| Note: This is fully compatible with signed modules. |
| |
| If in doubt, say N. |
| |
| choice |
| prompt "Compression algorithm" |
| depends on MODULE_COMPRESS |
| default MODULE_COMPRESS_GZIP |
| help |
| This determines which sort of compression will be used during |
| 'make modules_install'. |
| |
| GZIP (default) and XZ are supported. |
| |
| config MODULE_COMPRESS_GZIP |
| bool "GZIP" |
| |
| config MODULE_COMPRESS_XZ |
| bool "XZ" |
| |
| endchoice |
| |
| config TRIM_UNUSED_KSYMS |
| bool "Trim unused exported kernel symbols" |
| depends on MODULES && !UNUSED_SYMBOLS |
| help |
| The kernel and some modules make many symbols available for |
| other modules to use via EXPORT_SYMBOL() and variants. Depending |
| on the set of modules being selected in your kernel configuration, |
| many of those exported symbols might never be used. |
| |
| This option allows for unused exported symbols to be dropped from |
| the build. In turn, this provides the compiler more opportunities |
| (especially when using LTO) for optimizing the code and reducing |
| binary size. This might have some security advantages as well. |
| |
| If unsure, or if you need to build out-of-tree modules, say N. |
| |
| endif # MODULES |
| |
| config MODULES_TREE_LOOKUP |
| def_bool y |
| depends on PERF_EVENTS || TRACING |
| |
| config INIT_ALL_POSSIBLE |
| bool |
| help |
| Back when each arch used to define their own cpu_online_mask and |
| cpu_possible_mask, some of them chose to initialize cpu_possible_mask |
| 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 pursuing me down dark alleys. |
| |
| source "block/Kconfig" |
| |
| config PREEMPT_NOTIFIERS |
| bool |
| |
| config PADATA |
| depends on SMP |
| bool |
| |
| config ASN1 |
| tristate |
| help |
| Build a simple ASN.1 grammar compiler that produces a bytecode output |
| that can be interpreted by the ASN.1 stream decoder and used to |
| inform it as to what tags are to be expected in a stream and what |
| functions to call on what tags. |
| |
| source "kernel/Kconfig.locks" |