OSI services

The LFS provides several Operating System Interface (OSI) callable services specifically for PFSs.

The addresses of these routines are passed to a PFS during initialization in the OSI operations vector table (OSIT structure). For information about how the OSIT is passed to the PFS during initialization, see Activating and deactivating the PFS. See also Interface structures for C language servers and clients for more information about C language structures.

Table 1 shows the OSI services.

Table 1. OSI services
Service	Description
osi_copyin	Copy data to a PFS buffer
osi_copyout	Copy data to a user buffer
osi_copy64	Move data between user and PFS buffers with 64-bit addresses
osi_ctl	Pass control information to the kernel
osi_getcred	Obtain SAF UIDs, GIDs, and supplementary IDs
osi_getvnode	Get a vnode
osi_kipcget	Query interprocess communications
osi_kmsgctl	Control in-kernel messages
osi_kmsgget	Get a message queue ID
osi_kmsgrcv	Receive an in-kernel message from the queue
osi_kmsgsnd	Send an in-kernel message to the queue
osi_mountstatus	Report file system status
osi_post	General post
osi_sched	Schedule Part 2 of Async I/O
osi_selpost	Select post
osi_signal	Send a signal
osi_sleep	Wait for a resource
osi_thread	Fetch a module from a thread
osi_uiomove	Move data between buffers
osi_upda	Update Async I/O request
osi_wait	General wait
osi_wakeup	Wake a task waiting for a resource

This topic describes each of the OSI services, which are arranged in alphabetic order. The OSI services are callable services that are generally called only from within a PFS. Some of these services must be called from the same thread that is making a VFS or vnode call. The information about callable services from VFS callable services application programming interface applies here, with a few exceptions:

The service name is a C-language macro that invokes the particular service based on its address in the OSIT structure.
The three ways of invoking a module that are listed in VFS callable services application programming interface do not apply to these services. They must be called with the saved OSIT structure address, by using the macros listed in Table 1.
Assembler language programs must use the OSIT structure offsets for each service. These offsets can be found in the OSIT typedef in Interface structures for C language servers and clients.

Note: Any of the output parameters of a call can be modified by the system, whether the call is successful or not.