ipc_create (nr 505)

Create a bidirectional IPC channel pair.

Signature

ipc_create(fds_ptr: *mut [i32; 2], capacity: u32, flags: u32) → 0 or -errno

Arguments

Arg	Register	Description
fds_ptr	rdi	Pointer to 2-element i32 array for [send_fd, recv_fd]
capacity	rsi	Channel buffer capacity (max queued messages)
flags	rdx	`IPC_CLOEXEC` (0x1) to set FD_CLOEXEC on both fds

Return value

On success, writes [send_fd, recv_fd] to fds_ptr and returns 0.

Errors

Error	Condition
EFAULT	`fds_ptr` is invalid
EINVAL	Unknown flags
EMFILE	Process fd table is full

Description

Creates an IPC channel and returns two file descriptors: a send end and a receive end. Messages are fixed-size IpcMessage structs (56 bytes) containing:

struct IpcMessage {         // repr(C)
    uint64_t tag;           // User-defined message type
    uint64_t data[3];       // 24 bytes inline payload
    int32_t  fds[4];        // File descriptors to transfer (-1 = unused)
};

The channel supports capability-based fd passing: file descriptors listed in msg.fds are duplicated from the sender’s fd table and installed in the receiver’s fd table on delivery.

Channels can be used in both blocking mode (via ipc_send/ipc_recv syscalls) and async mode (via OP_IPC_SEND/OP_IPC_RECV on a completion port).

Implementation

osl/src/ipc.rs — sys_ipc_create

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