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C Library Reference
S
sysmgr_runstate(), sysmgr_runstate_dynamic()
Change the runstate of a processor

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      - sandbox_attach()
        Attach a sandbox
      - sandbox_create()
        Create a sandbox.
      - sandbox_delete()
        Delete a sandbox.
      - scalb()
        Load the exponent of a radix-independent floating point number
      - scalbln(), scalblnf(), scalblnl()
        Load the exponent of a radix-independent floating point number
      - scalbn(), scalbnf(), scalbnl()
        Load the exponent of a radix-independent floating point number
      - _scalloc()
        Allocate space for an array
      - scandir()
        Scan a directory
      - scanf()
        Scan formatted input from stdin
      - sched_getparam()
        Get the current scheduling parameters of a process
      - sched_get_priority_adjust()
        Calculate the allowable priority for the scheduling policy
      - sched_get_priority_max()
        Get the maximum priority for the scheduling policy
      - sched_get_priority_min()
        Get the minimum priority for the scheduling policy
      - sched_getscheduler()
        Get the current scheduling policy for a process
      - sched_param
        Structure that describes scheduling parameters
      - sched_rr_get_interval()
        Get the execution time limit of a process
      - sched_setparam()
        Change the priority of a process
      - sched_setscheduler()
        Change the priority and scheduling policy of a process
      - sched_yield()
        Yield to other ready threads at the same priority
      - SchedCtl(), SchedCtl_r()
        Control the scheduler
      - SchedGet(), SchedGet_r()
        Get the scheduling policy and parameters for a thread
      - SchedGetCpuNum()
        Get the index of the CPU that a thread is currently running on
      - SchedInfo(), SchedInfo_r()
        Get scheduler information
      - SchedSet(), SchedSet_r()
        Set the scheduling policy and parameters for a thread
      - SchedYield(), SchedYield_r()
        Yield to other threads
      - searchenv()
        Search the directories listed in an environment variable
      - seed48()
        Initialize the seed for a sequence of pseudo-random numbers
      - seekdir()
        Set the position for the next read of the directory stream
      - select(), pselect()
        Check for files that are ready for reading or writing or have an exceptional condition pending
      - select_attach()
        Attach a file descriptor to a dispatch handle
      - select_detach()
        Detach a file descriptor from a dispatch handle
      - select_query()
        Decode the last select event
      - sem_clockwait()
        Wait on a semaphore with a timeout measured against a specific clock
      - sem_close()
        Close a named semaphore
      - sem_destroy()
        Destroy an unnamed semaphore
      - sem_getvalue()
        Get the value of a named or unnamed semaphore
      - sem_init()
        Initialize an unnamed semaphore
      - sem_open()
        Create or access a named semaphore
      - sem_post()
        Increment a named or unnamed semaphore
      - sem_timedwait(), sem_timedwait_monotonic()
        Wait on a named or unnamed semaphore, with a timeout
      - sem_trywait()
        Wait on a named or unnamed semaphore, but don't block
      - sem_unlink()
        Destroy a named semaphore
      - sem_wait()
        Wait on a named or unnamed semaphore
      - send()
        Send a message to a connected socket
      - sendmmsg()
        Send multiple messages to a socket
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        Send a message and its header to a socket
      - sendto()
        Send a message to a socket at a specific address
      - servent
        Structure for information from the services database
      - set_ids_from_arg()
        Change the caller's identifiers, based on a given string
      - set_lowest_fd()
        Specify the lowest acceptable file descriptor
      - setbuf()
        Associate a buffer with a stream
      - setbuffer()
        Assign block buffering to a stream
      - setdomainname()
        Set the domain name of the current host
      - setegid()
        Set the effective group ID for a process
      - setenv()
        Create or change an environment variable
      - seteuid()
        Set the effective user ID
      - setgid()
        Set the real, effective and saved set-group IDs
      - setfsent()
        Open the filesystem table (/etc/fstab) file
      - setgrent()
        Rewind to the start of the group database file
      - setgroups()
        Set supplementary group IDs
      - setgroupspid()
        Set supplementary group IDs for a child process
      - sethostent()
        Open the host database file
      - sethostname()
        Set the name of the current host
      - SETIOV(), SETIOV_CONST()
        Fill in the fields of an iov_t structure
      - setitimer()
        Set the value of an interval timer
      - setjmp()
        Save the calling environment for longjmp()
      - setkey()
        Set the key used in encryption
      - setlinebuf()
        Assign line buffering to a stream
      - setlocale()
        Select a program's locale
      - setlogmask()
        Set the syslogd system log priority mask
      - setnetent()
        Open the network name database file
      - setpgid()
        Join or create a process group
      - setpgrp()
        Set the process group
      - setprotoent()
        Open the protocol name database file
      - setpwent()
        Rewind the password database file
      - setregid()
        Set real and effective group IDs
      - setreuid()
        Set the real and effective user IDs for the calling process
      - setrlimit(), setrlimit64()
        Set the limit on a system resource
      - setservent()
        Open the network services database file
      - setsid()
        Create a new session
      - setsockopt()
        Set options associated with a socket
      - setsockprefix() (io-pkt)
        Set or get the prefix for the networking stack path for the current thread
      - setspent()
        Rewind the shadow password database file
      - setstate()
        Reset the state of a pseudo-random number generator
      - settimeofday()
        Set the time and date
      - setuid()
        Set the real, effective and saved user IDs
      - setutent()
        Return to the beginning of the user-information file
      - setvbuf()
        Associate a buffer with a stream
      - _sfree()
        Deallocate a block of memory
      - shm_create_handle()
        Create a handle so a specific process can access a shared memory object
      - shm_ctl(), shm_ctl_special()
        Give special attributes to a shared memory object
      - shm_delete_handle()
        Delete a handle to a shared memory object
      - shm_open()
        Open a shared memory object based on a pathname
      - shm_open_handle()
        Open a shared memory object based on a handle
      - shm_revoke()
        Revoke mappings to shared memory
      - shm_unlink()
        Remove the name of a shared memory object
      - shutdown()
        Shut down part of a full-duplex connection
      - shutdown_system(), shutdown_system_with_reason()
        Shut down the system
      - sigaction()
        Examine or specify the action associated with a signal
      - struct sigaction
        Structure that specifies how to handle a signal
      - sigaddset()
        Add a signal to a set
      - sigblock()
        Add to the mask of signals to block
      - sigdelset()
        Delete a signal from a set
      - sigemptyset()
        Initialize a set to contain no signals
      - sigevent
        Structure that describes an event
      - sigfillset()
        Initialize a set to contain all signals
      - siginfo_t
        Information about a signal
      - sigismember()
        See if a given signal is in a given set
      - siglongjmp()
        Restore the environment saved by sigsetjmp(), including the signal mask
      - sigmask()
        Construct a mask for a signal number
      - signal()
        Set handling for exceptional conditions
      - SignalAction(), SignalAction_r()
        Examine and/or specify actions for signals
      - SignalKill(), SignalKill_r()
        Send a signal to a process group, process, or thread
      - SignalKillSigval(), SignalKillSigval_r()
        Send a signal to a process group, process, or thread
      - SignalProcmask(), SignalProcmask_r()
        Modify or examine a thread's signal-blocked mask
      - SignalSuspend(), SignalSuspend_r()
        Suspend a thread until a signal is received
      - SignalWaitinfo(), SignalWaitinfo_r()
        Select a pending signal
      - SignalWaitinfoMask(), SignalWaitinfoMask_r()
        Block a set of signals and then select a pending signal
      - signbit()
        Determine whether a floating-point number is negative
      - sigpause()
        Wait for a signal
      - sigpending()
        Examine the set of pending, masked signals for a process
      - sigprocmask()
        Modify or examine a thread's signal-blocked mask
      - sigqueue()
        Queue a signal to a process
      - sigsetjmp()
        Save the environment, including the signal mask
      - sigsetmask()
        Set the mask of signals to block
      - sigsuspend()
        Replace the signal mask, and then suspend the thread
      - sigtimedwait()
        Wait for a signal or a timeout
      - sigunblock()
        Unblock signals
      - sigwait()
        Wait for a pending signal
      - sigwaitinfo()
        Wait for a specified signal and return its information
      - sin(), sinf(), sinl()
        Calculate the sine of an angle
      - sinh(), sinhf(), sinhl()
        Compute the hyperbolic sine
      - sleep()
        Suspend a thread for a given length of time
      - _sleepon_broadcast()
        Wake up multiple threads
      - _sleepon_destroy()
        Destroy a sleepon
      - _sleepon_init()
        Initialize a sleepon
      - _sleepon_lock()
        Lock a sleepon
      - _sleepon_signal()
        Wake up a single thread
      - _sleepon_unlock()
        Unlock a sleepon
      - _sleepon_wait()
        Wait on a sleepon lock
      - slog2_close_log()
        Close a system logger file
      - slog2_dump_logs_to_file()
        Write a snapshot of slog2 logs to a file
      - slog2_find_buffer()
        Find the handle for a buffer with a given name
      - slog2_get_buffer_info()
        Get information about a slogger2 buffer
      - slog2_get_log_info()
        Get information about a log file
      - slog2_get_verbosity()
        Get the verbosity level of the entire buffer set
      - slog2_hash()
        Convert an input string into an obfuscated non-reversible hash string
      - slog2_obfuscate()
        Obfuscate file and directory names by replacing some characters
      - slog2_open_log()
        Open a system log for parsing
      - slog2_packet_cmp()
        Compare two slogger2 packets
      - slog2_packet_info_t
        Structure containing information about a packet
      - slog2_parse_all()
        Parse all slogger2 files
      - slog2_parse_dynamic_buffer(), slog2_parse_static_buffer()
        Parse a slogger2 buffer
      - slog2_register()
        Register and allocate a new slog2 buffer set
      - slog2_reset()
        Reset the state of slogger2 for the process
      - slog2_set_default_buffer()
        Set the default slog2 logging buffer
      - slog2_set_verbosity()
        Set the verbosity level for the entire buffer set
      - slog2c()
        Log a constant string in a slog2 buffer
      - slog2f()
        Log a printf-style string in a slog2 buffer
      - slog2fa()
        Log a printf-style string in a slog2 buffer
      - slogb()
        Send a message to the system logger
      - slogf()
        Send a message to the system logger
      - slogi()
        Send a message to the system logger
      - _smalloc()
        Allocate memory in blocks
      - snprintf()
        Write formatted output to a character array, up to a given maximum number of characters
      - sockatmark()
        Determine whether a socket is at the out-of-band mark
      - socket()
        Create an endpoint for communication
      - socketpair()
        Create a pair of connected sockets
      - sopen()
        Open a file for shared access
      - sopenfd()
        Open for shared access a file associated with a given descriptor
      - spawn()
        Create and execute a new child process
      - spawnl()
        Spawn a child process, given a list of arguments
      - spawnle()
        Spawn a child process, given a list of arguments and an environment
      - spawnlp()
        Spawn a child process, given a list of arguments and a relative path
      - spawnlpe()
        Spawn a child process, given a list of arguments, an environment, and a relative path
      - spawnp()
        Create and execute a new child process, given a relative path
      - spawnv()
        Spawn a child process, given a vector of arguments
      - spawnve()
        Spawn a child process, given a vector of arguments and an environment
      - spawnvp()
        Spawn a child process, given a vector of arguments and a relative path
      - spawnvpe()
        Spawn a child process, given a vector of arguments, an environment, and a relative path
      - sprintf()
        Print formatted output into a string
      - sqrt(), sqrtf(), sqrtl()
        Calculate the nonnegative square root of a number
      - srand()
        Start a new sequence of pseudo-random integers
      - srand48()
        Initialize a sequence of pseudo-random numbers
      - srandom()
        Set the seed for a pseudo-random number generator
      - _srealloc()
        Allocate, reallocate or free a block of memory
      - sscanf()
        Scan input from a character string
      - stat(), stat64()
        Get information about a file or directory, given a path
      - struct stat
        Data structure for information about a file or directory
      - stat_convert_form()
        Convert a stat structure from one form to another
      - static_assert()
        Display a diagnostic message at compile time
      - statvfs(), statvfs64()
        Get filesystem information, given a path
      - stderr
        The standard error stream
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        The standard input stream
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        The standard output stream
      - stpcpy()
        Copy a string and return a pointer to the end of the result
      - stpncpy()
        Copy a fixed-length string and return a pointer to the end of the result
      - straddstr()
        Concatenate one string on to the end of another
      - strcasecmp()
        Compare two strings, ignoring case
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        Find one string inside another, ignoring case
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        Concatenate two strings
      - strchr(), strchr_isr()
        Find the first occurrence of a character in a string
      - strcmp()
        Compare two strings
      - strcoll()
        Compare two strings, using the locale's collating sequence
      - strcpy(), strcpy_isr()
        Copy a string
      - strcspn()
        Count the characters at the beginning of a string that aren't in a given character set
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        Create a duplicate of a string
      - strerror()
        Convert an error number into an error message
      - strerror_r()
        Convert an error number into an error message (reentrant)
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        Format a time into a string
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        Size-bounded string copying and concatenation
      - strlen(), strlen_isr()
        Compute the length of a string
      - strlwr()
        Convert a string to lowercase
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        Compare two strings, ignoring case, up to a given length
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        Concatenate two strings, up to a maximum length
      - strncmp()
        Compare two strings, up to a given length
      - strncpy()
        Copy a string, to a maximum length
      - strndup()
        Create a duplicate of a string, up to a maximum length
      - strnlen()
        Compute the length of a string, to a maximum number of bytes
      - strpbrk()
        Find the first character in a string that's in a given character set
      - strptime()
        Convert a string into a time
      - strrchr()
        Find the last occurrence of a character in a string
      - strrev()
        Reverse a string
      - strsep()
        Separate a string into pieces marked by given delimiters
      - strsignal()
        Return the description of a signal
      - strspn()
        Count the characters at the beginning of a string that are in a given character set
      - strstr()
        Find one string inside another
      - strtod(), strtof(), strtold()
        Convert a string into a double-precision number
      - strtoimax(), strtoumax()
        Convert a string into an integer
      - strtok()
        Break a string into tokens
      - strtok_r()
        Break a string into tokens (reentrant)
      - strtol(), strtoll()
        Convert a string into a long integer
      - strtoul(), strtoull()
        Convert a string into an unsigned long integer
      - strupr()
        Convert a string to uppercase
      - strxfrm()
        Transform one string into another, to a given length
      - swab()
        Endian-swap a given number of bytes
      - swprintf()
        Print formatted wide-character output into a string
      - swscanf()
        Scan input from a wide-character string
      - symlink()
        Create a symbolic link to a path
      - symlinkat()
        Create a symbolic link to a path, at a given location
      - sync()
        Synchronize filesystem updates
      - SyncCondvarSignal(), SyncCondvarSignal_r()
        Wake up any threads that are blocked on a synchronization object
      - SyncCondvarWait(), SyncCondvarWait_r()
        Block a thread on a synchronization object
      - SyncCtl(), SyncCtl_r()
        Perform an operation on a synchronization object
      - SyncDestroy(), SyncDestroy_r()
        Destroy a synchronization object
      - SyncMutexEvent(), SyncMutexEvent_r()
        Attach an event to a mutex
      - SyncMutexLock(), SyncMutexLock_r()
        Lock a mutex synchronization object
      - SyncMutexRevive(), SyncMutexRevive_r()
        Revive a mutex that's in the DEAD state
      - SyncMutexUnlock(), SyncMutexUnlock_r()
        Unlock a mutex synchronization object
      - SyncSemPost(), SyncSemPost_r()
        Increment a semaphore
      - SyncSemWait(), SyncSemWait_r()
        Wait on a semaphore
      - SyncTypeCreate(), SyncTypeCreate_r()
        Create a synchronization object
      - sysconf()
        Return the value of a configurable system limit or option
      - sysctl(), sysctlbyname()
        Get or set information about the socket manager
      - syslog()
        Write a message to the syslogd system log
      - sysmgr_reboot()
        Reboot the system
      - sysmgr_runstate(), sysmgr_runstate_dynamic()
        Change the runstate of a processor
      - sysmgr_runstate_burst()
        Ask the system to turn on dynamically offlined CPUs
      - SYSPAGE_CPU_ENTRY()
        Return a CPU-specific entry from the system page
      - SYSPAGE_ENTRY()
        Return an entry from the system page
      - _syspage_ptr
        A pointer to the system page
      - SysSrandom()
        Supply entropy to the kernel's pseudorandom number generator
      - system()
        Execute a system command
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    This document provides a reference for the Wi-Fi Protected Access (WPA) control interface, which provides a C API for the WPA/IEEE 802.11i protocols in Wi-Fi client stations. Application developers who want to control WPA operations and get associated status and event data should read this reference.
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sysmgr_runstate(), sysmgr_runstate_dynamic()

Change the runstate of a processor

Synopsis:

#include <sys/sysmgr.h>

int sysmgr_runstate( unsigned cpu,
                     int enable );

int sysmgr_runstate_dynamic( unsigned cpu,
                             int enable );

Arguments:

cpu: The index of the CPU whose state you want to change.
enable: Zero to offline the processor; non-zero to bring it back online. For more details, see below.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The sysmgr_runstate() and sysmgr_runstate_dynamic() functions offline or online the specified CPU as follows:

sysmgr_runstate() manually takes a CPU offline (if enable is zero) or brings it online (if one).
sysmgr_runstate_dynamic() lets the kernel dynamically take a CPU on- or offline (if enable is one), depending on the system load.

These settings work together:


Runstate	Dynamic runstate	Action
0	—	The CPU is permanently offline
1	0	The CPU is permanently online (the default)
1	1	The CPU is dynamically brought on- or offline by the kernel, depending on load.

Note:

In order to successfully change the state, your process must have the PROCMGR_AID_RUNSTATE ability enabled. For more information, see procmgr_ability().
These functions don't turn the power on or off for the CPU; they tell the kernel whether or not to schedule threads on it. If you take a CPU offline, it sits on a WFI instruction (for ARM), or a HLT instruction (for x86). If you want to turn the power off for an idle CPU, use InterruptHookIdle2() to register a callback that shuts it down.

You can use sysmgr_runstate_burst() to notify the kernel that it should bring CPUs online because the system is about to get busy.

Returns:

EOK on success. If an error occurs, the function can return any value listed in the Errors section.

Errors:

EAGAIN: A needed resource was unavailable.
EINVAL: The CPU bits included invalid bits.
ENOMEM: There was insufficient memory to complete the operation.
EPERM: The calling process doesn't have the required permission of PROCMGR_AID_RUNSTATE; see procmgr_ability().

Classification:


Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes

Page updated: March 12, 2026