Copyright Digital Equipment Corp. All rights reserved.
Arguments
inadr
OpenVMS usage:address_range
type: longword (unsigned)
access: read only
mechanism: by reference-array reference or descriptor
Starting and ending virtual addresses of the pages that are to
be written to the section file if they have been modified. The
inadr argument is the address of a 2-longword array containing,
in order, the starting and ending process virtual addresses.
Addresses are adjusted up or down to CPU-specific pages.
Only the virtual page number portion of each virtual address is
used; the low-order byte-within-page bits are ignored.
$UPDSEC scans pages starting at the address contained in the
first longword specified by inadr and ending at the address
contained in the second longword. Within this range, $UPDSEC
locates read/write pages that have been modified and writes
them (contiguously, if possible) to the section file on disk.
Unmodified pages are also written to disk if they share the same
cluster with modified pages.
If the starting and ending virtual addresses are the same, a
single page is written to the section file if the page has been
modified.
The address specified by the second longword might be smaller
than the address specified by the first longword.
retadr
OpenVMS usage:address_range
type: longword (unsigned)
access: write only
mechanism: by reference-array reference or descriptor
Addresses of the first and last pages that were actually queued
for writing, in the first $QIO request, back to the section file
on disk. The retadr argument is the address of a 2-longword array
containing, in order, the addresses of the first and last pages.
Addresses always are adjusted up or down to fall on CPU-specific
boundaries.
If $UPDSEC returns an error condition value in R0, each longword
specified by retadr contains the value -1. In this case, an event
flag is not set, no asynchonous system trap (AST) is delivered,
and the I/O status block is not written to.
acmode
OpenVMS usage:access_mode
type: longword (unsigned)
access: read only
mechanism: by value
Access mode on behalf of which the service is performed. The
acmode argument is a longword containing the access mode. The
$PSLDEF macro defines the symbols for the four access modes.
The most privileged access mode used is the access mode of the
caller. A page cannot be written to disk unless the access mode
used by $UPDSEC is equal to or more privileged than the access
mode of the owner of the page to be written.
updflg
OpenVMS usage:longword_unsigned
type: longword (unsigned)
access: read only
mechanism: by value
Update specifier for read/write global sections. The updflg
argument is a longword value. The value 0 (the default) specifies
that all read/write pages in the global section are to be written
to the section file on disk, whether or not they have been
modified. The value 1 specifies that the caller is the only
or the last process having the global section mapped for write
access and that only modified pages should be written to the
section file on disk.
efn
OpenVMS usage:ef_number
type: longword (unsigned)
access: read only
mechanism: by value
Event flag to be set when the section file on disk is actually
updated. The efn argument is a longword specifying the number of
the event flag; however, $UPDSEC uses only the low-order byte.
If you do not specify efn, event flag 0 is used.
When you invoke $UPDSEC, the specified event flag or event flag 0
is cleared; when the update operation is complete, the event flag
is set.
iosb
OpenVMS usage:io_status_block
type: quadword (unsigned)
access: write only
mechanism: by reference
I/O status block to receive the final completion status of the
updating operation. The iosb argument is the address of the
quadword I/O status block.
When you invoke $UPDSEC, the I/O status block is cleared. After
the update operation is complete, that is, when all I/O to the
disk is complete, the I/O status block is written as follows:
o The first word contains the condition value returned by $QIO,
indicating the final completion status.
o The first bit in the second word is set only if an error
occurred during the I/O operation and the error was a hardware
write error. The remaining bits of the second word are zeros.
o The second longword contains the virtual address of the first
page that was not written.
Though this argument is optional, VSI strongly recommends that you
specify it for the following reasons:
o If you are using an event flag to signal the completion of
the service, you can test the I/O status block for a condition
value to be sure that the event flag was not set by an event
other than service completion.
o If you are using $SYNCH to synchronize completion of the
service, the I/O status block is a required argument for
$SYNCH.
o The condition value returned in R0 and the condition value
returned in the I/O status block provide information about
different aspects of the call to $UPDSEC. The condition
value returned in R0 gives you information about the success
or failure of the service call itself; the condition value
returned in the I/O status block gives you information about
the success or failure of the service operation. Therefore,
to accurately assess the success or failure of the call to
$UPDSEC, you must check the condition values returned in both
R0 and the I/O status block.
astadr
OpenVMS usage:ast_procedure
type: procedure value
access: call without stack unwinding
mechanism: by reference-procedure reference or descriptor
AST routine to be executed when the section file has been
updated. The astadr argument is the address of this routine.
If you specify astadr, the AST routine executes at the access
mode from which the section file update was requested.
astprm
OpenVMS usage:user_arg
type: longword (unsigned)
access: read only
mechanism: by value
AST parameter to be passed to the AST routine. The astprm
argument is this longword parameter.