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https://mirrors.bfsu.edu.cn/git/linux.git
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32bd7eb5a7
This is left over from commit 7c9414385e ("sched: Remove USER_SCHED"")
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Dhaval Giani <dhaval.giani@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Howells <dhowells@redhat.com>
LKML-Reference: <4BA9A05F.7010407@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
1252 lines
39 KiB
Plaintext
1252 lines
39 KiB
Plaintext
config ARCH
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string
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option env="ARCH"
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config KERNELVERSION
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string
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option env="KERNELVERSION"
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config DEFCONFIG_LIST
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string
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depends on !UML
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option defconfig_list
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default "/lib/modules/$UNAME_RELEASE/.config"
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default "/etc/kernel-config"
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default "/boot/config-$UNAME_RELEASE"
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default "$ARCH_DEFCONFIG"
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default "arch/$ARCH/defconfig"
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config CONSTRUCTORS
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bool
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depends on !UML
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default y
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menu "General setup"
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config EXPERIMENTAL
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bool "Prompt for development and/or incomplete code/drivers"
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---help---
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Some of the various things that Linux supports (such as network
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drivers, file systems, network protocols, etc.) can be in a state
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of development where the functionality, stability, or the level of
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testing is not yet high enough for general use. This is usually
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known as the "alpha-test" phase among developers. If a feature is
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currently in alpha-test, then the developers usually discourage
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uninformed widespread use of this feature by the general public to
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avoid "Why doesn't this work?" type mail messages. However, active
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testing and use of these systems is welcomed. Just be aware that it
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may not meet the normal level of reliability or it may fail to work
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in some special cases. Detailed bug reports from people familiar
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with the kernel internals are usually welcomed by the developers
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(before submitting bug reports, please read the documents
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<file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
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<file:Documentation/BUG-HUNTING>, and
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<file:Documentation/oops-tracing.txt> in the kernel source).
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This option will also make obsoleted drivers available. These are
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drivers that have been replaced by something else, and/or are
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scheduled to be removed in a future kernel release.
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Unless you intend to help test and develop a feature or driver that
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falls into this category, or you have a situation that requires
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using these features, you should probably say N here, which will
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cause the configurator to present you with fewer choices. If
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you say Y here, you will be offered the choice of using features or
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drivers that are currently considered to be in the alpha-test phase.
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config BROKEN
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bool
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config BROKEN_ON_SMP
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bool
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depends on BROKEN || !SMP
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default y
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config LOCK_KERNEL
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bool
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depends on SMP || PREEMPT
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default y
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config INIT_ENV_ARG_LIMIT
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int
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default 32 if !UML
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default 128 if UML
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help
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Maximum of each of the number of arguments and environment
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variables passed to init from the kernel command line.
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config LOCALVERSION
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string "Local version - append to kernel release"
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help
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Append an extra string to the end of your kernel version.
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This will show up when you type uname, for example.
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The string you set here will be appended after the contents of
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any files with a filename matching localversion* in your
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object and source tree, in that order. Your total string can
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be a maximum of 64 characters.
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config LOCALVERSION_AUTO
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bool "Automatically append version information to the version string"
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default y
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help
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This will try to automatically determine if the current tree is a
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release tree by looking for git tags that belong to the current
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top of tree revision.
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A string of the format -gxxxxxxxx will be added to the localversion
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if a git-based tree is found. The string generated by this will be
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appended after any matching localversion* files, and after the value
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set in CONFIG_LOCALVERSION.
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(The actual string used here is the first eight characters produced
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by running the command:
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$ git rev-parse --verify HEAD
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which is done within the script "scripts/setlocalversion".)
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config HAVE_KERNEL_GZIP
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bool
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config HAVE_KERNEL_BZIP2
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bool
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config HAVE_KERNEL_LZMA
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bool
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config HAVE_KERNEL_LZO
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bool
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choice
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prompt "Kernel compression mode"
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default KERNEL_GZIP
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depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
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help
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The linux kernel is a kind of self-extracting executable.
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Several compression algorithms are available, which differ
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in efficiency, compression and decompression speed.
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Compression speed is only relevant when building a kernel.
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Decompression speed is relevant at each boot.
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If you have any problems with bzip2 or lzma compressed
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kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
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version of this functionality (bzip2 only), for 2.4, was
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supplied by Christian Ludwig)
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High compression options are mostly useful for users, who
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are low on disk space (embedded systems), but for whom ram
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size matters less.
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If in doubt, select 'gzip'
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config KERNEL_GZIP
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bool "Gzip"
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depends on HAVE_KERNEL_GZIP
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help
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The old and tried gzip compression. It provides a good balance
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between compression ratio and decompression speed.
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config KERNEL_BZIP2
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bool "Bzip2"
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depends on HAVE_KERNEL_BZIP2
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help
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Its compression ratio and speed is intermediate.
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Decompression speed is slowest among the three. The kernel
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size is about 10% smaller with bzip2, in comparison to gzip.
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Bzip2 uses a large amount of memory. For modern kernels you
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will need at least 8MB RAM or more for booting.
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config KERNEL_LZMA
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bool "LZMA"
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depends on HAVE_KERNEL_LZMA
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help
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The most recent compression algorithm.
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Its ratio is best, decompression speed is between the other
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two. Compression is slowest. The kernel size is about 33%
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smaller with LZMA in comparison to gzip.
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config KERNEL_LZO
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bool "LZO"
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depends on HAVE_KERNEL_LZO
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help
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Its compression ratio is the poorest among the 4. The kernel
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size is about about 10% bigger than gzip; however its speed
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(both compression and decompression) is the fastest.
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endchoice
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config SWAP
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bool "Support for paging of anonymous memory (swap)"
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depends on MMU && BLOCK
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default y
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help
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This option allows you to choose whether you want to have support
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for so called swap devices or swap files in your kernel that are
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used to provide more virtual memory than the actual RAM present
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in your computer. If unsure say Y.
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config SYSVIPC
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bool "System V IPC"
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---help---
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Inter Process Communication is a suite of library functions and
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system calls which let processes (running programs) synchronize and
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exchange information. It is generally considered to be a good thing,
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and some programs won't run unless you say Y here. In particular, if
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you want to run the DOS emulator dosemu under Linux (read the
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DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
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you'll need to say Y here.
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You can find documentation about IPC with "info ipc" and also in
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section 6.4 of the Linux Programmer's Guide, available from
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<http://www.tldp.org/guides.html>.
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config SYSVIPC_SYSCTL
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bool
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depends on SYSVIPC
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depends on SYSCTL
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default y
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config POSIX_MQUEUE
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bool "POSIX Message Queues"
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depends on NET && EXPERIMENTAL
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---help---
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POSIX variant of message queues is a part of IPC. In POSIX message
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queues every message has a priority which decides about succession
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of receiving it by a process. If you want to compile and run
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programs written e.g. for Solaris with use of its POSIX message
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queues (functions mq_*) say Y here.
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POSIX message queues are visible as a filesystem called 'mqueue'
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and can be mounted somewhere if you want to do filesystem
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operations on message queues.
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If unsure, say Y.
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config POSIX_MQUEUE_SYSCTL
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bool
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depends on POSIX_MQUEUE
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depends on SYSCTL
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default y
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config BSD_PROCESS_ACCT
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bool "BSD Process Accounting"
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help
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If you say Y here, a user level program will be able to instruct the
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kernel (via a special system call) to write process accounting
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information to a file: whenever a process exits, information about
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that process will be appended to the file by the kernel. The
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information includes things such as creation time, owning user,
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command name, memory usage, controlling terminal etc. (the complete
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list is in the struct acct in <file:include/linux/acct.h>). It is
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up to the user level program to do useful things with this
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information. This is generally a good idea, so say Y.
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config BSD_PROCESS_ACCT_V3
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bool "BSD Process Accounting version 3 file format"
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depends on BSD_PROCESS_ACCT
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default n
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help
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If you say Y here, the process accounting information is written
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in a new file format that also logs the process IDs of each
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process and it's parent. Note that this file format is incompatible
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with previous v0/v1/v2 file formats, so you will need updated tools
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for processing it. A preliminary version of these tools is available
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at <http://www.gnu.org/software/acct/>.
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config TASKSTATS
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bool "Export task/process statistics through netlink (EXPERIMENTAL)"
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depends on NET
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default n
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help
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Export selected statistics for tasks/processes through the
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generic netlink interface. Unlike BSD process accounting, the
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statistics are available during the lifetime of tasks/processes as
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responses to commands. Like BSD accounting, they are sent to user
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space on task exit.
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Say N if unsure.
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config TASK_DELAY_ACCT
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bool "Enable per-task delay accounting (EXPERIMENTAL)"
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depends on TASKSTATS
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help
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Collect information on time spent by a task waiting for system
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resources like cpu, synchronous block I/O completion and swapping
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in pages. Such statistics can help in setting a task's priorities
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relative to other tasks for cpu, io, rss limits etc.
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Say N if unsure.
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config TASK_XACCT
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bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
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depends on TASKSTATS
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help
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Collect extended task accounting data and send the data
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to userland for processing over the taskstats interface.
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Say N if unsure.
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config TASK_IO_ACCOUNTING
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bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
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depends on TASK_XACCT
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help
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Collect information on the number of bytes of storage I/O which this
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task has caused.
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Say N if unsure.
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config AUDIT
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bool "Auditing support"
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depends on NET
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help
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Enable auditing infrastructure that can be used with another
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kernel subsystem, such as SELinux (which requires this for
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logging of avc messages output). Does not do system-call
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auditing without CONFIG_AUDITSYSCALL.
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config AUDITSYSCALL
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bool "Enable system-call auditing support"
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depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
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default y if SECURITY_SELINUX
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help
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Enable low-overhead system-call auditing infrastructure that
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can be used independently or with another kernel subsystem,
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such as SELinux. To use audit's filesystem watch feature, please
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ensure that INOTIFY is configured.
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config AUDIT_TREE
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def_bool y
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depends on AUDITSYSCALL
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select INOTIFY
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menu "RCU Subsystem"
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choice
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prompt "RCU Implementation"
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default TREE_RCU
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config TREE_RCU
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bool "Tree-based hierarchical RCU"
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help
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This option selects the RCU implementation that is
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designed for very large SMP system with hundreds or
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thousands of CPUs. It also scales down nicely to
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smaller systems.
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config TREE_PREEMPT_RCU
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bool "Preemptable tree-based hierarchical RCU"
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depends on PREEMPT
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help
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This option selects the RCU implementation that is
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designed for very large SMP systems with hundreds or
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thousands of CPUs, but for which real-time response
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is also required. It also scales down nicely to
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smaller systems.
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config TINY_RCU
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bool "UP-only small-memory-footprint RCU"
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depends on !SMP
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help
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This option selects the RCU implementation that is
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designed for UP systems from which real-time response
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is not required. This option greatly reduces the
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memory footprint of RCU.
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endchoice
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config RCU_TRACE
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bool "Enable tracing for RCU"
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depends on TREE_RCU || TREE_PREEMPT_RCU
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help
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This option provides tracing in RCU which presents stats
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in debugfs for debugging RCU implementation.
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Say Y here if you want to enable RCU tracing
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Say N if you are unsure.
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config RCU_FANOUT
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int "Tree-based hierarchical RCU fanout value"
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range 2 64 if 64BIT
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range 2 32 if !64BIT
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depends on TREE_RCU || TREE_PREEMPT_RCU
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default 64 if 64BIT
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default 32 if !64BIT
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help
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This option controls the fanout of hierarchical implementations
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of RCU, allowing RCU to work efficiently on machines with
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large numbers of CPUs. This value must be at least the cube
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root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
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systems and up to 262,144 for 64-bit systems.
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Select a specific number if testing RCU itself.
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Take the default if unsure.
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config RCU_FANOUT_EXACT
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bool "Disable tree-based hierarchical RCU auto-balancing"
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depends on TREE_RCU || TREE_PREEMPT_RCU
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default n
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help
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This option forces use of the exact RCU_FANOUT value specified,
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regardless of imbalances in the hierarchy. This is useful for
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testing RCU itself, and might one day be useful on systems with
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strong NUMA behavior.
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Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
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Say N if unsure.
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config RCU_FAST_NO_HZ
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bool "Accelerate last non-dyntick-idle CPU's grace periods"
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depends on TREE_RCU && NO_HZ && SMP
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default n
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help
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This option causes RCU to attempt to accelerate grace periods
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in order to allow the final CPU to enter dynticks-idle state
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more quickly. On the other hand, this option increases the
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overhead of the dynticks-idle checking, particularly on systems
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with large numbers of CPUs.
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Say Y if energy efficiency is critically important, particularly
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if you have relatively few CPUs.
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Say N if you are unsure.
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config TREE_RCU_TRACE
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def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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select DEBUG_FS
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help
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This option provides tracing for the TREE_RCU and
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TREE_PREEMPT_RCU implementations, permitting Makefile to
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trivially select kernel/rcutree_trace.c.
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endmenu # "RCU Subsystem"
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config IKCONFIG
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tristate "Kernel .config support"
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---help---
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This option enables the complete Linux kernel ".config" file
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contents to be saved in the kernel. It provides documentation
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of which kernel options are used in a running kernel or in an
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on-disk kernel. This information can be extracted from the kernel
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image file with the script scripts/extract-ikconfig and used as
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input to rebuild the current kernel or to build another kernel.
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It can also be extracted from a running kernel by reading
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/proc/config.gz if enabled (below).
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config IKCONFIG_PROC
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bool "Enable access to .config through /proc/config.gz"
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depends on IKCONFIG && PROC_FS
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---help---
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This option enables access to the kernel configuration file
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through /proc/config.gz.
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config LOG_BUF_SHIFT
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int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
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range 12 21
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default 17
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help
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Select kernel log buffer size as a power of 2.
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Examples:
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17 => 128 KB
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16 => 64 KB
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15 => 32 KB
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14 => 16 KB
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13 => 8 KB
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12 => 4 KB
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#
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# Architectures with an unreliable sched_clock() should select this:
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#
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config HAVE_UNSTABLE_SCHED_CLOCK
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bool
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menuconfig CGROUPS
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boolean "Control Group support"
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depends on EVENTFD
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help
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This option adds support for grouping sets of processes together, for
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use with process control subsystems such as Cpusets, CFS, memory
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controls or device isolation.
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See
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- Documentation/scheduler/sched-design-CFS.txt (CFS)
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- Documentation/cgroups/ (features for grouping, isolation
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and resource control)
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Say N if unsure.
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if CGROUPS
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config CGROUP_DEBUG
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bool "Example debug cgroup subsystem"
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depends on CGROUPS
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default n
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help
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This option enables a simple cgroup subsystem that
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exports useful debugging information about the cgroups
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framework.
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Say N if unsure.
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config CGROUP_NS
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bool "Namespace cgroup subsystem"
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depends on CGROUPS
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help
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Provides a simple namespace cgroup subsystem to
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provide hierarchical naming of sets of namespaces,
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for instance virtual servers and checkpoint/restart
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jobs.
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config CGROUP_FREEZER
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bool "Freezer cgroup subsystem"
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depends on CGROUPS
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help
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|
Provides a way to freeze and unfreeze all tasks in a
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cgroup.
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config CGROUP_DEVICE
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bool "Device controller for cgroups"
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depends on CGROUPS && EXPERIMENTAL
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help
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Provides a cgroup implementing whitelists for devices which
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a process in the cgroup can mknod or open.
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config CPUSETS
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bool "Cpuset support"
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depends on CGROUPS
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help
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|
This option will let you create and manage CPUSETs which
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allow dynamically partitioning a system into sets of CPUs and
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|
Memory Nodes and assigning tasks to run only within those sets.
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|
This is primarily useful on large SMP or NUMA systems.
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Say N if unsure.
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config PROC_PID_CPUSET
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bool "Include legacy /proc/<pid>/cpuset file"
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depends on CPUSETS
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default y
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config CGROUP_CPUACCT
|
|
bool "Simple CPU accounting cgroup subsystem"
|
|
depends on CGROUPS
|
|
help
|
|
Provides a simple Resource Controller for monitoring the
|
|
total CPU consumed by the tasks in a cgroup.
|
|
|
|
config RESOURCE_COUNTERS
|
|
bool "Resource counters"
|
|
help
|
|
This option enables controller independent resource accounting
|
|
infrastructure that works with cgroups.
|
|
depends on CGROUPS
|
|
|
|
config CGROUP_MEM_RES_CTLR
|
|
bool "Memory Resource Controller for Control Groups"
|
|
depends on CGROUPS && RESOURCE_COUNTERS
|
|
select MM_OWNER
|
|
help
|
|
Provides a memory resource controller that manages both anonymous
|
|
memory and page cache. (See Documentation/cgroups/memory.txt)
|
|
|
|
Note that setting this option increases fixed memory overhead
|
|
associated with each page of memory in the system. By this,
|
|
20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
|
|
usage tracking struct at boot. Total amount of this is printed out
|
|
at boot.
|
|
|
|
Only enable when you're ok with these trade offs and really
|
|
sure you need the memory resource controller. Even when you enable
|
|
this, you can set "cgroup_disable=memory" at your boot option to
|
|
disable memory resource controller and you can avoid overheads.
|
|
(and lose benefits of memory resource controller)
|
|
|
|
This config option also selects MM_OWNER config option, which
|
|
could in turn add some fork/exit overhead.
|
|
|
|
config CGROUP_MEM_RES_CTLR_SWAP
|
|
bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
|
|
depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
|
|
help
|
|
Add swap management feature to memory resource controller. When you
|
|
enable this, you can limit mem+swap usage per cgroup. In other words,
|
|
when you disable this, memory resource controller has no cares to
|
|
usage of swap...a process can exhaust all of the swap. This extension
|
|
is useful when you want to avoid exhaustion swap but this itself
|
|
adds more overheads and consumes memory for remembering information.
|
|
Especially if you use 32bit system or small memory system, please
|
|
be careful about enabling this. When memory resource controller
|
|
is disabled by boot option, this will be automatically disabled and
|
|
there will be no overhead from this. Even when you set this config=y,
|
|
if boot option "noswapaccount" is set, swap will not be accounted.
|
|
Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
|
|
size is 4096bytes, 512k per 1Gbytes of swap.
|
|
|
|
menuconfig CGROUP_SCHED
|
|
bool "Group CPU scheduler"
|
|
depends on EXPERIMENTAL && CGROUPS
|
|
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 RT_GROUP_SCHED
|
|
bool "Group scheduling for SCHED_RR/FIFO"
|
|
depends on EXPERIMENTAL
|
|
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
|
|
|
|
endif # CGROUPS
|
|
|
|
config MM_OWNER
|
|
bool
|
|
|
|
config SYSFS_DEPRECATED
|
|
bool
|
|
|
|
config SYSFS_DEPRECATED_V2
|
|
bool "enable deprecated sysfs features to support old userspace tools"
|
|
depends on SYSFS
|
|
default n
|
|
select SYSFS_DEPRECATED
|
|
help
|
|
This option switches the layout of sysfs to the deprecated
|
|
version. Do not use it on recent distributions.
|
|
|
|
The current sysfs layout features a unified device tree at
|
|
/sys/devices/, which is able to express a hierarchy between
|
|
class devices. If the deprecated option is set to Y, the
|
|
unified device tree is split into a bus device tree at
|
|
/sys/devices/ and several individual class device trees at
|
|
/sys/class/. The class and bus devices will be connected by
|
|
"<subsystem>:<name>" and the "device" links. The "block"
|
|
class devices, will not show up in /sys/class/block/. Some
|
|
subsystems will suppress the creation of some devices which
|
|
depend on the unified device tree.
|
|
|
|
This option is not a pure compatibility option that can
|
|
be safely enabled on newer distributions. It will change the
|
|
layout of sysfs to the non-extensible deprecated version,
|
|
and disable some features, which can not be exported without
|
|
confusing older userspace tools. Since 2007/2008 all major
|
|
distributions do not enable this option, and ship no tools which
|
|
depend on the deprecated layout or this option.
|
|
|
|
If you are using a new kernel on an older distribution, or use
|
|
older userspace tools, you might need to say Y here. Do not say Y,
|
|
if the original kernel, that came with your distribution, has
|
|
this option set to N.
|
|
|
|
config RELAY
|
|
bool "Kernel->user space relay support (formerly relayfs)"
|
|
help
|
|
This option enables support for relay interface support in
|
|
certain file systems (such as debugfs).
|
|
It is designed to provide an efficient mechanism for tools and
|
|
facilities to relay large amounts of data from kernel space to
|
|
user space.
|
|
|
|
If unsure, say N.
|
|
|
|
config NAMESPACES
|
|
bool "Namespaces support" if EMBEDDED
|
|
default !EMBEDDED
|
|
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.
|
|
|
|
config UTS_NS
|
|
bool "UTS namespace"
|
|
depends on NAMESPACES
|
|
help
|
|
In this namespace tasks see different info provided with the
|
|
uname() system call
|
|
|
|
config IPC_NS
|
|
bool "IPC namespace"
|
|
depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
|
|
help
|
|
In this namespace tasks work with IPC ids which correspond to
|
|
different IPC objects in different namespaces.
|
|
|
|
config USER_NS
|
|
bool "User namespace (EXPERIMENTAL)"
|
|
depends on NAMESPACES && EXPERIMENTAL
|
|
help
|
|
This allows containers, i.e. vservers, to use user namespaces
|
|
to provide different user info for different servers.
|
|
If unsure, say N.
|
|
|
|
config PID_NS
|
|
bool "PID Namespaces (EXPERIMENTAL)"
|
|
default n
|
|
depends on NAMESPACES && EXPERIMENTAL
|
|
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.
|
|
|
|
Unless you want to work with an experimental feature
|
|
say N here.
|
|
|
|
config NET_NS
|
|
bool "Network namespace"
|
|
default n
|
|
depends on NAMESPACES && EXPERIMENTAL && NET
|
|
help
|
|
Allow user space to create what appear to be multiple instances
|
|
of the network stack.
|
|
|
|
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/initrd.txt> 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
|
|
|
|
config CC_OPTIMIZE_FOR_SIZE
|
|
bool "Optimize for size"
|
|
default y
|
|
help
|
|
Enabling this option will pass "-Os" instead of "-O2" to gcc
|
|
resulting in a smaller kernel.
|
|
|
|
If unsure, say Y.
|
|
|
|
config SYSCTL
|
|
bool
|
|
|
|
config ANON_INODES
|
|
bool
|
|
|
|
menuconfig EMBEDDED
|
|
bool "Configure standard kernel features (for small systems)"
|
|
help
|
|
This option allows certain base kernel options and settings
|
|
to be disabled or tweaked. This is for specialized
|
|
environments which can tolerate a "non-standard" kernel.
|
|
Only use this if you really know what you are doing.
|
|
|
|
config UID16
|
|
bool "Enable 16-bit UID system calls" if EMBEDDED
|
|
depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
|
|
default y
|
|
help
|
|
This enables the legacy 16-bit UID syscall wrappers.
|
|
|
|
config SYSCTL_SYSCALL
|
|
bool "Sysctl syscall support" if EMBEDDED
|
|
depends on PROC_SYSCTL
|
|
default y
|
|
select SYSCTL
|
|
---help---
|
|
sys_sysctl uses binary paths that have been found challenging
|
|
to properly maintain and use. The interface in /proc/sys
|
|
using paths with ascii names is now the primary path to this
|
|
information.
|
|
|
|
Almost nothing using the binary sysctl interface so if you are
|
|
trying to save some space it is probably safe to disable this,
|
|
making your kernel marginally smaller.
|
|
|
|
If unsure say Y here.
|
|
|
|
config KALLSYMS
|
|
bool "Load all symbols for debugging/ksymoops" if EMBEDDED
|
|
default y
|
|
help
|
|
Say Y here to let the kernel print out symbolic crash information and
|
|
symbolic stack backtraces. This increases the size of the kernel
|
|
somewhat, as all symbols have to be loaded into the kernel image.
|
|
|
|
config KALLSYMS_ALL
|
|
bool "Include all symbols in kallsyms"
|
|
depends on DEBUG_KERNEL && KALLSYMS
|
|
help
|
|
Normally kallsyms only contains the symbols of functions, for nicer
|
|
OOPS messages. Some debuggers can use kallsyms for other
|
|
symbols too: say Y here to include all symbols, if you need them
|
|
and you don't care about adding 300k to the size of your kernel.
|
|
|
|
Say N.
|
|
|
|
config KALLSYMS_EXTRA_PASS
|
|
bool "Do an extra kallsyms pass"
|
|
depends on KALLSYMS
|
|
help
|
|
If kallsyms is not working correctly, the build will fail with
|
|
inconsistent kallsyms data. If that occurs, log a bug report and
|
|
turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
|
|
Always say N here unless you find a bug in kallsyms, which must be
|
|
reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
|
|
you wait for kallsyms to be fixed.
|
|
|
|
|
|
config HOTPLUG
|
|
bool "Support for hot-pluggable devices" if EMBEDDED
|
|
default y
|
|
help
|
|
This option is provided for the case where no hotplug or uevent
|
|
capabilities is wanted by the kernel. You should only consider
|
|
disabling this option for embedded systems that do not use modules, a
|
|
dynamic /dev tree, or dynamic device discovery. Just say Y.
|
|
|
|
config PRINTK
|
|
default y
|
|
bool "Enable support for printk" if EMBEDDED
|
|
help
|
|
This option enables normal printk support. Removing it
|
|
eliminates most of the message strings from the kernel image
|
|
and makes the kernel more or less silent. As this makes it
|
|
very difficult to diagnose system problems, saying N here is
|
|
strongly discouraged.
|
|
|
|
config BUG
|
|
bool "BUG() support" if EMBEDDED
|
|
default y
|
|
help
|
|
Disabling this option eliminates support for BUG and WARN, reducing
|
|
the size of your kernel image and potentially quietly ignoring
|
|
numerous fatal conditions. You should only consider disabling this
|
|
option for embedded systems with no facilities for reporting errors.
|
|
Just say Y.
|
|
|
|
config ELF_CORE
|
|
default y
|
|
bool "Enable ELF core dumps" if EMBEDDED
|
|
help
|
|
Enable support for generating core dumps. Disabling saves about 4k.
|
|
|
|
config PCSPKR_PLATFORM
|
|
bool "Enable PC-Speaker support" if EMBEDDED
|
|
depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
|
|
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 EMBEDDED
|
|
help
|
|
Disabling this option reduces the size of miscellaneous core
|
|
kernel data structures. This saves memory on small machines,
|
|
but may reduce performance.
|
|
|
|
config FUTEX
|
|
bool "Enable futex support" if EMBEDDED
|
|
default y
|
|
select RT_MUTEXES
|
|
help
|
|
Disabling this option will cause the kernel to be built without
|
|
support for "fast userspace mutexes". The resulting kernel may not
|
|
run glibc-based applications correctly.
|
|
|
|
config EPOLL
|
|
bool "Enable eventpoll support" if EMBEDDED
|
|
default y
|
|
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 EMBEDDED
|
|
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 EMBEDDED
|
|
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 EMBEDDED
|
|
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.
|
|
|
|
config SHMEM
|
|
bool "Use full shmem filesystem" if EMBEDDED
|
|
default y
|
|
depends on MMU
|
|
help
|
|
The shmem is an internal filesystem used to manage shared memory.
|
|
It is backed by swap and manages resource limits. It is also exported
|
|
to userspace as tmpfs if TMPFS is enabled. Disabling this
|
|
option replaces shmem and tmpfs with the much simpler ramfs code,
|
|
which may be appropriate on small systems without swap.
|
|
|
|
config AIO
|
|
bool "Enable AIO support" if EMBEDDED
|
|
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 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
|
|
|
|
menu "Kernel Performance Events And Counters"
|
|
|
|
config PERF_EVENTS
|
|
bool "Kernel performance events and counters"
|
|
default y if (PROFILING || PERF_COUNTERS)
|
|
depends on HAVE_PERF_EVENTS
|
|
select ANON_INODES
|
|
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 PERF_COUNTERS
|
|
bool "Kernel performance counters (old config option)"
|
|
depends on HAVE_PERF_EVENTS
|
|
help
|
|
This config has been obsoleted by the PERF_EVENTS
|
|
config option - please see that one for details.
|
|
|
|
It has no effect on the kernel whether you enable
|
|
it or not, it is a compatibility placeholder.
|
|
|
|
Say N if unsure.
|
|
|
|
config DEBUG_PERF_USE_VMALLOC
|
|
default n
|
|
bool "Debug: use vmalloc to back perf mmap() buffers"
|
|
depends on PERF_EVENTS && DEBUG_KERNEL
|
|
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 EMBEDDED
|
|
help
|
|
VM event counters are needed for event counts to be shown.
|
|
This option allows the disabling of the VM event counters
|
|
on EMBEDDED systems. /proc/vmstat will only show page counts
|
|
if VM event counters are disabled.
|
|
|
|
config PCI_QUIRKS
|
|
default y
|
|
bool "Enable PCI quirk workarounds" if EMBEDDED
|
|
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 SLUB_DEBUG
|
|
default y
|
|
bool "Enable SLUB debugging support" if EMBEDDED
|
|
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 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"
|
|
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)"
|
|
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 EMBEDDED
|
|
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 MMAP_ALLOW_UNINITIALIZED
|
|
bool "Allow mmapped anonymous memory to be uninitialized"
|
|
depends on EMBEDDED && !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 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"
|
|
|
|
config SLOW_WORK
|
|
default n
|
|
bool
|
|
help
|
|
The slow work thread pool provides a number of dynamically allocated
|
|
threads that can be used by the kernel to perform operations that
|
|
take a relatively long time.
|
|
|
|
An example of this would be CacheFiles doing a path lookup followed
|
|
by a series of mkdirs and a create call, all of which have to touch
|
|
disk.
|
|
|
|
See Documentation/slow-work.txt.
|
|
|
|
config SLOW_WORK_DEBUG
|
|
bool "Slow work debugging through debugfs"
|
|
default n
|
|
depends on SLOW_WORK && DEBUG_FS
|
|
help
|
|
Display the contents of the slow work run queue through debugfs,
|
|
including items currently executing.
|
|
|
|
See Documentation/slow-work.txt.
|
|
|
|
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
|
|
boolean
|
|
|
|
config BASE_SMALL
|
|
int
|
|
default 0 if BASE_FULL
|
|
default 1 if !BASE_FULL
|
|
|
|
menuconfig 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.
|
|
|
|
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 && EXPERIMENTAL
|
|
help
|
|
This option allows you to force a module to unload, even if the
|
|
kernel believes it is unsafe: the kernel will remove the module
|
|
without waiting for anyone to stop using it (using the -f option to
|
|
rmmod). This is mainly for kernel developers and desperate users.
|
|
If unsure, say N.
|
|
|
|
config MODVERSIONS
|
|
bool "Module versioning support"
|
|
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"
|
|
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.
|
|
|
|
endif # MODULES
|
|
|
|
config INIT_ALL_POSSIBLE
|
|
bool
|
|
help
|
|
Back when each arch used to define their own cpu_online_map and
|
|
cpu_possible_map, some of them chose to initialize cpu_possible_map
|
|
with all 1s, and others with all 0s. When they were centralised,
|
|
it was better to provide this option than to break all the archs
|
|
and have several arch maintainers pursuing me down dark alleys.
|
|
|
|
config STOP_MACHINE
|
|
bool
|
|
default y
|
|
depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
|
|
help
|
|
Need stop_machine() primitive.
|
|
|
|
source "block/Kconfig"
|
|
|
|
config PREEMPT_NOTIFIERS
|
|
bool
|
|
|
|
config PADATA
|
|
depends on SMP
|
|
bool
|
|
|
|
source "kernel/Kconfig.locks"
|