PLOCK(2)                             SysV                             PLOCK(2)



NAME
     plock - lock process, text, or data in memory

SYNOPSIS
     #include <sys/lock.h>

     int plock (op)
     int op;

DESCRIPTION
     Domain/OS SysV provides plock for compatibility only.  The subsequent
     discussion describes plock's function as documented for UNIX System V,
     Release 3.

     plock allows the calling process to lock its text segment (text lock),
     its data segment (data lock), or both (process lock) into memory.  Locked
     segments are immune to all routine swapping.  plock also allows these
     segments to be unlocked.  The effective user ID of the calling process
     must be super-user to use this call.  op specifies the following:

     PROCLOCK  Process lock -- Lock text and data segments into memory

     TXTLOCK   Text lock -- Lock text segment into memory

     DATLOCK   Data lock -- Lock data segment into memory

     UNLOCK    Remove locks

ERRORS
     plock will fail and not perform the requested operation if one or more of
     the following are true:

     [EPERM]    The effective user ID of the calling process is not super-
                user.

     [EINVAL]   op is equal to PROCLOCK and a process lock, a text lock, or a
                data lock already exists on the calling process.

     [EINVAL]   op is equal to TXTLOCK and a text lock, or a process lock
                already exists on the calling process.

     [EINVAL]   op is equal to DATLOCK and a data lock or a process lock
                already exists on the calling process.

     [EINVAL]   op is equal to UNLOCK and no type of lock exists on the
                calling process.

     [EAGAIN]   Not enough memory.

SEE ALSO
     exec(2), exit(2), fork(2).
     Domain/OS Design Principles.

DIAGNOSTICS
     A successful call returns 0.  A failed call returns -1 and sets errno.

NOTES
     The functionality plock purports to provide in UNIX System V, Release 3
     is irrelevant to the single-level store virtual memory management scheme
     of Domain/OS.  In that scheme, the disk, as well as physical memory, acts
     as primary storage, so that the notion of "swapping" is irrelevant.

     plock cannot prevent paging, the process whereby Domain/OS does I/O to
     the disk.