1769 lines
56 KiB
Plaintext
1769 lines
56 KiB
Plaintext
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
|
|
|
|
menu "General setup"
|
|
|
|
config EXPERIMENTAL
|
|
bool
|
|
default y
|
|
|
|
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 LOCALVERSION
|
|
string "Local version - append to kernel release"
|
|
help
|
|
Append an extra string to the end of your kernel version.
|
|
This will show up when you type uname, for example.
|
|
The string you set here will be appended after the contents of
|
|
any files with a filename matching localversion* in your
|
|
object and source tree, in that order. Your total string can
|
|
be a maximum of 64 characters.
|
|
|
|
config LOCALVERSION_AUTO
|
|
bool "Automatically append version information to the version string"
|
|
default y
|
|
help
|
|
This will try to automatically determine if the current tree is a
|
|
release tree by looking for git tags that belong to the current
|
|
top of tree revision.
|
|
|
|
A string of the format -gxxxxxxxx will be added to the localversion
|
|
if a git-based tree is found. The string generated by this will be
|
|
appended after any matching localversion* files, and after the value
|
|
set in CONFIG_LOCALVERSION.
|
|
|
|
(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
|
|
|
|
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
|
|
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.
|
|
|
|
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 FHANDLE
|
|
bool "open by fhandle syscalls"
|
|
select EXPORTFS
|
|
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 AUDIT
|
|
bool "Auditing support"
|
|
depends on NET
|
|
help
|
|
Enable auditing infrastructure that can be used with another
|
|
kernel subsystem, such as SELinux (which requires this for
|
|
logging of avc messages output). Does not do system-call
|
|
auditing without CONFIG_AUDITSYSCALL.
|
|
|
|
config AUDITSYSCALL
|
|
bool "Enable system-call auditing support"
|
|
depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
|
|
default y if SECURITY_SELINUX
|
|
help
|
|
Enable low-overhead system-call auditing infrastructure that
|
|
can be used independently or with another kernel subsystem,
|
|
such as SELinux.
|
|
|
|
config AUDIT_WATCH
|
|
def_bool y
|
|
depends on AUDITSYSCALL
|
|
select FSNOTIFY
|
|
|
|
config AUDIT_TREE
|
|
def_bool y
|
|
depends on AUDITSYSCALL
|
|
select FSNOTIFY
|
|
|
|
config AUDIT_LOGINUID_IMMUTABLE
|
|
bool "Make audit loginuid immutable"
|
|
depends on AUDIT
|
|
help
|
|
The config option toggles if a task setting its loginuid requires
|
|
CAP_SYS_AUDITCONTROL or if that task should require no special permissions
|
|
but should instead only allow setting its loginuid if it was never
|
|
previously set. On systems which use systemd or a similar central
|
|
process to restart login services this should be set to true. On older
|
|
systems in which an admin would typically have to directly stop and
|
|
start processes this should be set to false. Setting this to true allows
|
|
one to drop potentially dangerous capabilites from the login tasks,
|
|
but may not be backwards compatible with older init systems.
|
|
|
|
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
|
|
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
|
|
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 && 64BIT
|
|
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.
|
|
|
|
config IRQ_TIME_ACCOUNTING
|
|
bool "Fine granularity task level IRQ time accounting"
|
|
depends on HAVE_IRQ_TIME_ACCOUNTING
|
|
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.
|
|
|
|
endchoice
|
|
|
|
config BSD_PROCESS_ACCT
|
|
bool "BSD Process Accounting"
|
|
help
|
|
If you say Y here, a user level program will be able to instruct the
|
|
kernel (via a special system call) to write process accounting
|
|
information to a file: whenever a process exits, information about
|
|
that process will be appended to the file by the kernel. The
|
|
information includes things such as creation time, owning user,
|
|
command name, memory usage, controlling terminal etc. (the complete
|
|
list is in the struct acct in <file:include/linux/acct.h>). It is
|
|
up to the user level program to do useful things with this
|
|
information. This is generally a good idea, so say Y.
|
|
|
|
config BSD_PROCESS_ACCT_V3
|
|
bool "BSD Process Accounting version 3 file format"
|
|
depends on BSD_PROCESS_ACCT
|
|
default n
|
|
help
|
|
If you say Y here, the process accounting information is written
|
|
in a new file format that also logs the process IDs of each
|
|
process and it's parent. Note that this file format is incompatible
|
|
with previous v0/v1/v2 file formats, so you will need updated tools
|
|
for processing it. A preliminary version of these tools is available
|
|
at <http://www.gnu.org/software/acct/>.
|
|
|
|
config TASKSTATS
|
|
bool "Export task/process statistics through netlink"
|
|
depends on NET
|
|
default n
|
|
help
|
|
Export selected statistics for tasks/processes through the
|
|
generic netlink interface. Unlike BSD process accounting, the
|
|
statistics are available during the lifetime of tasks/processes as
|
|
responses to commands. Like BSD accounting, they are sent to user
|
|
space on task exit.
|
|
|
|
Say N if unsure.
|
|
|
|
config TASK_DELAY_ACCT
|
|
bool "Enable per-task delay accounting"
|
|
depends on TASKSTATS
|
|
help
|
|
Collect information on time spent by a task waiting for system
|
|
resources like cpu, synchronous block I/O completion and swapping
|
|
in pages. Such statistics can help in setting a task's priorities
|
|
relative to other tasks for cpu, io, rss limits etc.
|
|
|
|
Say N if unsure.
|
|
|
|
config 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"
|
|
|
|
choice
|
|
prompt "RCU Implementation"
|
|
default TREE_RCU
|
|
|
|
config TREE_RCU
|
|
bool "Tree-based hierarchical RCU"
|
|
depends on !PREEMPT && SMP
|
|
help
|
|
This option selects the RCU implementation that is
|
|
designed for very large SMP system with hundreds or
|
|
thousands of CPUs. It also scales down nicely to
|
|
smaller systems.
|
|
|
|
config TREE_PREEMPT_RCU
|
|
bool "Preemptible tree-based hierarchical RCU"
|
|
depends on 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 "UP-only small-memory-footprint RCU"
|
|
depends on !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 TINY_PREEMPT_RCU
|
|
bool "Preemptible UP-only small-memory-footprint RCU"
|
|
depends on PREEMPT && !SMP
|
|
help
|
|
This option selects the RCU implementation that is designed
|
|
for real-time UP systems. This option greatly reduces the
|
|
memory footprint of RCU.
|
|
|
|
endchoice
|
|
|
|
config PREEMPT_RCU
|
|
def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
|
|
help
|
|
This option enables preemptible-RCU code that is common between
|
|
the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
|
|
|
|
config RCU_STALL_COMMON
|
|
def_bool ( TREE_RCU || TREE_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 CONTEXT_TRACKING
|
|
bool
|
|
|
|
config RCU_USER_QS
|
|
bool "Consider userspace as in RCU extended quiescent state"
|
|
depends on HAVE_CONTEXT_TRACKING && SMP
|
|
select CONTEXT_TRACKING
|
|
help
|
|
This option sets hooks on kernel / userspace boundaries and
|
|
puts RCU in extended quiescent state when the CPU runs in
|
|
userspace. It means that when a CPU runs in userspace, it is
|
|
excluded from the global RCU state machine and thus doesn't
|
|
try to keep the timer tick on for RCU.
|
|
|
|
Unless you want to hack and help the development of the full
|
|
dynticks mode, you shouldn't enable this option. It also
|
|
adds unnecessary overhead.
|
|
|
|
If unsure say N
|
|
|
|
config CONTEXT_TRACKING_FORCE
|
|
bool "Force context tracking"
|
|
depends on CONTEXT_TRACKING
|
|
help
|
|
Probe on user/kernel boundaries by default in order to
|
|
test the features that rely on it such as userspace RCU extended
|
|
quiescent states.
|
|
This test is there for debugging until we have a real user like the
|
|
full dynticks mode.
|
|
|
|
config RCU_FANOUT
|
|
int "Tree-based hierarchical RCU fanout value"
|
|
range 2 64 if 64BIT
|
|
range 2 32 if !64BIT
|
|
depends on TREE_RCU || TREE_PREEMPT_RCU
|
|
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 RCU_FANOUT if 64BIT
|
|
range 2 RCU_FANOUT if !64BIT
|
|
depends on TREE_RCU || TREE_PREEMPT_RCU
|
|
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.
|
|
|
|
Select a specific number if testing RCU itself.
|
|
|
|
Select the maximum permissible value for large systems.
|
|
|
|
Take the default if unsure.
|
|
|
|
config RCU_FANOUT_EXACT
|
|
bool "Disable tree-based hierarchical RCU auto-balancing"
|
|
depends on TREE_RCU || TREE_PREEMPT_RCU
|
|
default n
|
|
help
|
|
This option forces use of the exact RCU_FANOUT value specified,
|
|
regardless of imbalances in the hierarchy. This is useful for
|
|
testing RCU itself, and might one day be useful on systems with
|
|
strong NUMA behavior.
|
|
|
|
Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
|
|
|
|
Say N if unsure.
|
|
|
|
config RCU_FAST_NO_HZ
|
|
bool "Accelerate last non-dyntick-idle CPU's grace periods"
|
|
depends on NO_HZ && SMP
|
|
default n
|
|
help
|
|
This option causes RCU to attempt to accelerate grace periods in
|
|
order to allow CPUs to enter dynticks-idle state more quickly.
|
|
On the other hand, this option increases the overhead of the
|
|
dynticks-idle checking, thus degrading scheduling latency.
|
|
|
|
Say Y if energy efficiency is critically important, and you don't
|
|
care about real-time response.
|
|
|
|
Say N if you are unsure.
|
|
|
|
config TREE_RCU_TRACE
|
|
def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
|
|
select DEBUG_FS
|
|
help
|
|
This option provides tracing for the TREE_RCU and
|
|
TREE_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
|
|
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_BOOST_PRIO
|
|
int "Real-time priority to boost RCU readers to"
|
|
range 1 99
|
|
depends on RCU_BOOST
|
|
default 1
|
|
help
|
|
This option specifies the real-time priority to which long-term
|
|
preempted RCU readers are to be boosted. 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_BOOST_PRIO to a priority higher then the highest-priority
|
|
real-time CPU-bound thread. The default RCU_BOOST_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_BOOST_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_BOOST_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 || TREE_PREEMPT_RCU
|
|
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 ("rcuoN") will be created to
|
|
invoke callbacks, where the "N" is the CPU being offloaded.
|
|
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 reduced OS jitter on selected CPUs.
|
|
Say N here if you are unsure.
|
|
|
|
endmenu # "RCU Subsystem"
|
|
|
|
config IKCONFIG
|
|
tristate "Kernel .config support"
|
|
---help---
|
|
This option enables the complete Linux kernel ".config" file
|
|
contents to be saved in the kernel. It provides documentation
|
|
of which kernel options are used in a running kernel or in an
|
|
on-disk kernel. This information can be extracted from the kernel
|
|
image file with the script scripts/extract-ikconfig and used as
|
|
input to rebuild the current kernel or to build another kernel.
|
|
It can also be extracted from a running kernel by reading
|
|
/proc/config.gz if enabled (below).
|
|
|
|
config IKCONFIG_PROC
|
|
bool "Enable access to .config through /proc/config.gz"
|
|
depends on IKCONFIG && PROC_FS
|
|
---help---
|
|
This option enables access to the kernel configuration file
|
|
through /proc/config.gz.
|
|
|
|
config LOG_BUF_SHIFT
|
|
int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
|
|
range 12 21
|
|
default 17
|
|
help
|
|
Select kernel log buffer size as a power of 2.
|
|
Examples:
|
|
17 => 128 KB
|
|
16 => 64 KB
|
|
15 => 32 KB
|
|
14 => 16 KB
|
|
13 => 8 KB
|
|
12 => 4 KB
|
|
|
|
#
|
|
# Architectures with an unreliable sched_clock() should select this:
|
|
#
|
|
config HAVE_UNSTABLE_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 (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
|
|
|
|
#
|
|
# For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
|
|
config ARCH_WANTS_PROT_NUMA_PROT_NONE
|
|
bool
|
|
|
|
config ARCH_USES_NUMA_PROT_NONE
|
|
bool
|
|
default y
|
|
depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
|
|
depends on NUMA_BALANCING
|
|
|
|
config NUMA_BALANCING_DEFAULT_ENABLED
|
|
bool "Automatically enable NUMA aware memory/task placement"
|
|
default y
|
|
depends on NUMA_BALANCING
|
|
help
|
|
If set, autonumic NUMA balancing will be enabled if running on a NUMA
|
|
machine.
|
|
|
|
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 is references to the node the task is running on.
|
|
|
|
This system will be inactive on UMA systems.
|
|
|
|
menuconfig CGROUPS
|
|
boolean "Control Group support"
|
|
depends on EVENTFD
|
|
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/cgroups/ (features for grouping, isolation
|
|
and resource control)
|
|
|
|
Say N if unsure.
|
|
|
|
if CGROUPS
|
|
|
|
config CGROUP_DEBUG
|
|
bool "Example debug cgroup subsystem"
|
|
default n
|
|
help
|
|
This option enables a simple cgroup subsystem that
|
|
exports useful debugging information about the cgroups
|
|
framework.
|
|
|
|
Say N if unsure.
|
|
|
|
config CGROUP_FREEZER
|
|
bool "Freezer cgroup subsystem"
|
|
help
|
|
Provides a way to freeze and unfreeze all tasks in a
|
|
cgroup.
|
|
|
|
config CGROUP_DEVICE
|
|
bool "Device controller for cgroups"
|
|
help
|
|
Provides a cgroup implementing whitelists for devices which
|
|
a process in the cgroup can mknod or open.
|
|
|
|
config CPUSETS
|
|
bool "Cpuset support"
|
|
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_CPUACCT
|
|
bool "Simple CPU accounting cgroup subsystem"
|
|
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.
|
|
|
|
config MEMCG
|
|
bool "Memory Resource Controller for Control Groups"
|
|
depends on 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 MEMCG_SWAP
|
|
bool "Memory Resource Controller Swap Extension"
|
|
depends on MEMCG && SWAP
|
|
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 "swapaccount=0" 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.
|
|
config MEMCG_SWAP_ENABLED
|
|
bool "Memory Resource Controller Swap Extension 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 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 MEMCG_KMEM
|
|
bool "Memory Resource Controller Kernel Memory accounting"
|
|
depends on MEMCG
|
|
depends on SLUB || SLAB
|
|
help
|
|
The Kernel Memory extension for Memory Resource Controller can limit
|
|
the amount of memory used by kernel objects in the system. Those are
|
|
fundamentally different from the entities handled by the standard
|
|
Memory Controller, which are page-based, and can be swapped. Users of
|
|
the kmem extension can use it to guarantee that no group of processes
|
|
will ever exhaust kernel resources alone.
|
|
|
|
config CGROUP_HUGETLB
|
|
bool "HugeTLB Resource Controller for Control Groups"
|
|
depends on RESOURCE_COUNTERS && HUGETLB_PAGE
|
|
default n
|
|
help
|
|
Provides a cgroup Resource 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 CGROUP_PERF
|
|
bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
|
|
depends on PERF_EVENTS && CGROUPS
|
|
help
|
|
This option extends the per-cpu mode to restrict monitoring to
|
|
threads which belong to the cgroup specified and run on the
|
|
designated cpu.
|
|
|
|
Say N if unsure.
|
|
|
|
menuconfig CGROUP_SCHED
|
|
bool "Group CPU scheduler"
|
|
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 BLK_CGROUP
|
|
bool "Block 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/cgroups/blkio-controller.txt for more information.
|
|
|
|
config DEBUG_BLK_CGROUP
|
|
bool "Enable Block 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.
|
|
|
|
endif # CGROUPS
|
|
|
|
config CHECKPOINT_RESTORE
|
|
bool "Checkpoint/restore support" if EXPERT
|
|
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
|
|
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"
|
|
depends on UIDGID_CONVERTED
|
|
select UIDGID_STRICT_TYPE_CHECKS
|
|
|
|
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 and MEMCG_KMEM options 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 UIDGID_CONVERTED
|
|
# True if all of the selected software conmponents are known
|
|
# to have uid_t and gid_t converted to kuid_t and kgid_t
|
|
# where appropriate and are otherwise safe to use with
|
|
# the user namespace.
|
|
bool
|
|
default y
|
|
|
|
# Filesystems
|
|
depends on XFS_FS = n
|
|
|
|
config UIDGID_STRICT_TYPE_CHECKS
|
|
bool "Require conversions between uid/gids and their internal representation"
|
|
depends on UIDGID_CONVERTED
|
|
default n
|
|
help
|
|
While the nececessary conversions are being added to all subsystems this option allows
|
|
the code to continue to build for unconverted subsystems.
|
|
|
|
Say Y here if you want the strict type checking enabled
|
|
|
|
config SCHED_AUTOGROUP
|
|
bool "Automatic process group scheduling"
|
|
select EVENTFD
|
|
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 MM_OWNER
|
|
bool
|
|
|
|
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)"
|
|
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/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"
|
|
help
|
|
Enabling this option will pass "-Os" instead of "-O2" to gcc
|
|
resulting in a smaller kernel.
|
|
|
|
If unsure, say N.
|
|
|
|
config SYSCTL
|
|
bool
|
|
|
|
config ANON_INODES
|
|
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 HAVE_UID16
|
|
bool
|
|
|
|
config UID16
|
|
bool "Enable 16-bit UID system calls" if EXPERT
|
|
depends on HAVE_UID16
|
|
default y
|
|
help
|
|
This enables the legacy 16-bit UID syscall wrappers.
|
|
|
|
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 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 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 HOTPLUG
|
|
def_bool y
|
|
|
|
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 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 HAVE_PCSPKR_PLATFORM
|
|
bool
|
|
|
|
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 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.
|
|
|
|
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 EMBEDDED
|
|
bool "Embedded system"
|
|
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
|
|
|
|
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
|
|
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
|
|
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 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 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 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 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 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 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
|
|
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
|
|
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.
|
|
|
|
config MODULE_SIG
|
|
bool "Module signature verification"
|
|
depends on MODULES
|
|
select KEYS
|
|
select CRYPTO
|
|
select ASYMMETRIC_KEY_TYPE
|
|
select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
|
|
select PUBLIC_KEY_ALGO_RSA
|
|
select ASN1
|
|
select OID_REGISTRY
|
|
select X509_CERTIFICATE_PARSER
|
|
help
|
|
Check modules for valid signatures upon load: the signature
|
|
is simply appended to the module. For more information see
|
|
Documentation/module-signing.txt.
|
|
|
|
!!!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
|
|
|
|
endif # MODULES
|
|
|
|
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.
|
|
|
|
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
|
|
|
|
# Can be selected by architectures with broken toolchains
|
|
# that get confused by correct const<->read_only section
|
|
# mappings
|
|
config BROKEN_RODATA
|
|
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"
|