zephyr/kernel/Kconfig

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# Kconfig - kernel configuration options
#
# Copyright (c) 2014-2015 Wind River Systems, Inc.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1) Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
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# 2) Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
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#
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# may be used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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#
choice
prompt "Kernel Type"
default MICROKERNEL
config NANOKERNEL
bool "Nano Kernel"
config MICROKERNEL
bool "Micro Kernel"
endchoice
menu "General Kernel Options"
config SYS_CLOCK_TICKS_PER_SEC
int
prompt "System tick frequency (in ticks/second)"
default 100
depends on !NO_ISRS
help
This option specifies the frequency of the system clock in Hz.
config SYS_CLOCK_HW_CYCLES_PER_SEC
int "System clock's h/w timer frequency"
default 0
help
This option specifies the frequency of the hardware timer used for the
system clock (in Hz). It is normally set by the platform's defconfig file
and the user should generally avoid modifying it via the menu configuration.
config SYS_CLOCK_EXISTS
bool
# omit prompt to signify a "hidden" option
default n if (SYS_CLOCK_TICKS_PER_SEC = 0)
default y
help
This option specifies that the kernel lacks timer support.
config INIT_STACKS
bool
prompt "Initialize stack areas"
default n
help
This option instructs the kernel to initialize stack areas with a
known value (0xaa) before they are first used, so that the high
water mark can be easily determined. This applies to the stack areas
for both tasks and fibers, as well as for the microkernel server's command
stack.
config XIP
bool
prompt "Execute in place"
help
This option allows the kernel to operate with its text and read-only
sections residing in ROM (or similar read-only memory). Not all platforms
support this option so it must be used with care; you must also
supply a linker command file when building your image. Enabling this
option increases both the code and data footprint of the image.
config ENHANCED_SECURITY
bool
prompt "Enhanced security features"
default y if ARCH="x86"
default n
help
This option enables all security features supported by the kernel,
including those that can have a significant impact on system
footprint or performance; it also prevents the use of certain kernel
features that have known security risks.
Users can customize these settings using the CUSTOM_SECURITY option
in the "Security Options" menu.
config EVENT_LOGGER
bool
prompt "Enable event logger"
default n
help
Enable event logging feature. Allow the usage of a ring buffer to
transmit event messages with a single interface to collect them.
config KERNEL_PROFILER
bool
prompt "Enable profiler features"
default n
select EVENT_LOGGER
help
This feature enables the usage of the profiling logger. Provides the
logging of sleep events (either entering or leaving low power conditions),
context switch events, interrupt events, boot events and a method to
collect these profile messages.
config PROFILER_BUFFER_SIZE
int
prompt "Profiler buffer size"
default 128
depends on KERNEL_PROFILER
help
Buffer size in 32-bit words.
menu "Profiler points"
depends on KERNEL_PROFILER
config PROFILER_CONTEXT_SWITCH
bool
prompt "Context switch profiler point"
default n
depends on KERNEL_PROFILER
help
Enable the context switch event messages.
config PROFILER_INTERRUPT
bool
prompt "Interrupt profiler point"
default n
depends on KERNEL_PROFILER
help
Enable interrupt event messages. These messages provide the following
information: The time when interrupts occur.
config PROFILER_SLEEP
bool
prompt "Sleep profiler point"
default n
depends on KERNEL_PROFILER && ADVANCED_POWER_MANAGEMENT
help
Enable low power condition event messages. These messages provide the
following information:
- When the CPU went to sleep mode.
- When the CPU woke up.
- The ID of the interrupt that woke the CPU up.
endmenu
menu "Security Options"
depends on ENHANCED_SECURITY
config CUSTOM_SECURITY
bool
prompt "Customized security"
default n
help
This option allow users to disable enhanced security features they do
not wish to use or enable the use of features with security exposures.
config STACK_CANARIES
bool
prompt "Compiler stack canaries" if CUSTOM_SECURITY
default n
help
This option enables compiler stack canaries support on most functions
in the kernel. (Kernel functions that reside in LKMs do NOT have
stack canary support, due to limitations of the LKM technology.)
If stack canaries are supported by the compiler, it will emit
extra code that inserts a canary value into the stack frame when
a function is entered and validates this value upon exit.
Stack corruption (such as that caused by buffer overflow) results
in a fatal error condition for the running entity.
Enabling this option can result in a significant increase
in footprint and an associated decrease in performance.
If stack canaries are not supported by the compiler, enabling this
option has no effect.
endmenu
endmenu
source "kernel/nanokernel/Kconfig"
config TICKLESS_IDLE
bool
prompt "Tickless idle"
default y
depends on ADVANCED_POWER_MANAGEMENT
help
This option suppresses periodic system clock interrupts whenever the
kernel becomes idle. This permits the system to remain in a power
saving state for extended periods without having to wake up to
service each tick as it occurs.
config TICKLESS_IDLE_THRESH
int
prompt "Tickless idle threshold"
default 3
depends on TICKLESS_IDLE && MICROKERNEL
help
This option disables clock interrupt suppression when the kernel idles
for only a short period of time. It specifies the minimum number of
ticks that must occur before the next kernel timer expires in order
for suppression to happen.
if MICROKERNEL
source "kernel/microkernel/Kconfig"
endif