VMS Help System Services, $DELTVA  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Deletes a range of addresses from a process's virtual address
    space. Upon successful completion of the service, the deleted
    pages are inaccessible, and references to them cause access
    violations.

    Format

      SYS$DELTVA  inadr ,[retadr] ,[acmode]

    C Prototype

      int sys$deltva  (struct _va_range *inadr, struct _va_range

                      *retadr, unsigned int acmode);

    Arguments

 inadr

    OpenVMS usage:address_range
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Starting and ending virtual addresses of the pages to be
    deleted. The inadr argument is the address of a 2-longword array
    containing, in order, the starting and ending process virtual
    addresses. If the starting and ending virtual addresses are the
    same, a single page is deleted. The addresses are adjusted up or
    down to fall on CPU-specific page boundaries. Only the virtual
    page number portion of each virtual address is used; the low-
    order byte-within-page bits are ignored.

    The $DELTVA service deletes pages starting at the address
    contained in the second longword of the inadr argument and ending
    at the address in the first longword. Thus, if you use the same
    address array for both the Create Virtual Address Space ($CRETVA)
    and the $DELTVA services, the pages are deleted in the reverse
    order from which they were created.

 retadr

    OpenVMS usage:address_range
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Starting and ending process virtual addresses of the pages that
    $DELTVA has deleted. The retadr argument is the address of a
    2-longword array containing, in order, the starting and ending
    process virtual addresses.

 acmode

    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode on behalf of which the service is to be performed.
    The acmode argument is a longword containing the access mode.

    The most privileged access mode used is the access mode of the
    caller. The calling process can delete pages only if those pages
    are owned by an access mode equal to or less privileged than the
    access mode of the calling process.