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menu "Interprocess Communication (IPC)"
config RT_USING_POSIX_PIPE
bool "Enable pipe and FIFO"
select RT_USING_POSIX_FS
select RT_USING_POSIX_DEVIO
select RT_USING_POSIX_POLL
select RT_USING_RESOURCE_ID
default n
help
Enable POSIX pipes and FIFOs for inter-process communication.
Provides:
- Anonymous pipes: pipe(pipefd)
- Named pipes (FIFOs): mkfifo(path, mode)
- Unidirectional byte streams
- Blocking and non-blocking I/O
Features:
- Simple producer-consumer pattern
- Works with select/poll for multiplexing
- File descriptor based (can use read/write)
Use cases:
- Parent-child process communication
- Shell command pipelines
- Simple message passing
- Event notification
Buffer size: RT_USING_POSIX_PIPE_SIZE
Enable for POSIX pipe/FIFO support.
Essential for shell pipeline and process IPC.
config RT_USING_POSIX_PIPE_SIZE
int "Set pipe buffer size"
depends on RT_USING_POSIX_PIPE
default 512
help
Size of pipe buffer in bytes.
Default: 512 bytes
Trade-offs:
Larger buffer:
+ More data can be buffered
+ Better performance for burst writes
- More memory per pipe
Smaller buffer:
+ Less memory usage
- More frequent blocking on writes
Typical values: 512-4096 bytes
Adjust based on typical message sizes and memory constraints.
# We have't implement of 'systemv ipc', so hide it firstly.
#
# config RT_USING_POSIX_IPC_SYSTEM_V
# bool "Enable System V IPC"
# default n
# help
# System V supplies an alternative form of interprocess communication consisting of thress
# features: shared memory, message, and semaphores.
config RT_USING_POSIX_MESSAGE_QUEUE
bool "Enable posix message queue <mqueue.h>"
select RT_USING_POSIX_CLOCK
select RT_USING_MESSAGEQUEUE_PRIORITY
select RT_USING_DFS_MQUEUE
default n
help
Enable POSIX message queues for IPC.
Provides POSIX message queue APIs:
- mq_open(): Open/create message queue
- mq_send()/mq_receive(): Send/receive messages
- mq_timedsend()/mq_timedreceive(): With timeout
- mq_notify(): Async notification
- mq_getattr()/mq_setattr(): Queue attributes
Features:
- Priority-based message delivery
- Named queues (visible in /dev/mqueue)
- Blocking and non-blocking modes
- Timeout support
- Asynchronous notification
vs. Pipes:
+ Message boundaries preserved
+ Priority-based delivery
+ Can be used with select/poll
- More overhead per message
Use cases:
- Process communication with priorities
- Event notification systems
- Service request queues
- RT-Smart IPC
Requires DFS with MQUEUE support.
Enable for POSIX message queue IPC.
config RT_USING_POSIX_MESSAGE_SEMAPHORE
bool "Enable posix semaphore <semaphore.h>"
select RT_USING_POSIX_CLOCK
default n
help
Enable POSIX named and unnamed semaphores.
Provides semaphore APIs:
- sem_init()/sem_destroy(): Unnamed semaphores
- sem_open()/sem_close()/sem_unlink(): Named semaphores
- sem_wait()/sem_trywait()/sem_timedwait(): Acquire
- sem_post(): Release
- sem_getvalue(): Get current value
Types:
- Unnamed (memory-based): For thread synchronization
- Named (file-based): For process synchronization
Features:
- Counting semaphore (value > 1)
- Binary semaphore (value = 0 or 1)
- Timeout support
- Non-blocking try operation
Use cases:
- Thread/process synchronization
- Resource counting
- Producer-consumer patterns
- Mutual exclusion
vs. Mutex:
+ Can be used for signaling (sem_post from any thread)
+ Counting capability
- No ownership tracking
Enable for POSIX semaphore support.
Essential for POSIX synchronization.
comment "Socket is in the 'Network' category"
endmenu
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