Constant MEMBARRIER_CMD_QUERY

pub const MEMBARRIER_CMD_QUERY: i32 = 0;

Available on crate feature dep_nc only.

enum membarrier_cmd - membarrier system call command

@MEMBARRIER_CMD_QUERY: Query the set of supported commands. It returns a bitmask of valid commands. @MEMBARRIER_CMD_GLOBAL: Execute a memory barrier on all running threads. Upon return from system call, the caller thread is ensured that all running threads have passed through a state where all memory accesses to user-space addresses match program order between entry to and return from the system call (non-running threads are de facto in such a state). This covers threads from all processes running on the system. This command returns 0. @MEMBARRIER_CMD_GLOBAL_EXPEDITED: Execute a memory barrier on all running threads of all processes which previously registered with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED. Upon return from system call, the caller thread is ensured that all running threads have passed through a state where all memory accesses to user-space addresses match program order between entry to and return from the system call (non-running threads are de facto in such a state). This only covers threads from processes which registered with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED. This command returns 0. Given that registration is about the intent to receive the barriers, it is valid to invoke MEMBARRIER_CMD_GLOBAL_EXPEDITED from a non-registered process. @MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED: Register the process intent to receive MEMBARRIER_CMD_GLOBAL_EXPEDITED memory barriers. Always returns 0. @MEMBARRIER_CMD_PRIVATE_EXPEDITED: Execute a memory barrier on each running thread belonging to the same process as the current thread. Upon return from system call, the caller thread is ensured that all its running threads siblings have passed through a state where all memory accesses to user-space addresses match program order between entry to and return from the system call (non-running threads are de facto in such a state). This only covers threads from the same process as the caller thread. This command returns 0 on success. The “expedited” commands complete faster than the non-expedited ones, they never block, but have the downside of causing extra overhead. A process needs to register its intent to use the private expedited command prior to using it, otherwise this command returns -EPERM. @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED: Register the process intent to use MEMBARRIER_CMD_PRIVATE_EXPEDITED. Always returns 0. @MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE: In addition to provide memory ordering guarantees described in MEMBARRIER_CMD_PRIVATE_EXPEDITED, ensure the caller thread, upon return from system call, that all its running threads siblings have executed a core serializing instruction. (architectures are required to guarantee that non-running threads issue core serializing instructions before they resume user-space execution). This only covers threads from the same process as the caller thread. This command returns 0 on success. The “expedited” commands complete faster than the non-expedited ones, they never block, but have the downside of causing extra overhead. If this command is not implemented by an architecture, -EINVAL is returned. A process needs to register its intent to use the private expedited sync core command prior to using it, otherwise this command returns -EPERM. @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE: Register the process intent to use MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE. If this command is not implemented by an architecture, -EINVAL is returned. Returns 0 on success. @MEMBARRIER_CMD_SHARED: Alias to MEMBARRIER_CMD_GLOBAL. Provided for header backward compatibility.

Command to be passed to the membarrier system call. The commands need to be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to the value 0.