The PHY_IO privilege lets the user's process execute the Queue
I/O Request ($QIO) system service to perform physical-level I/O
operations.
Usually, process I/O requests are handled indirectly by use
of an I/O package such as OpenVMS Record Management Services (RMS).
However, to increase their control over I/O operations and to improve
the efficiency of their applications, skilled users sometimes prefer
to handle directly the interface between their process and a system
I/O driver program. They can do this by executing the $QIO system
service; in many instances, the operation called for is a physical-level
I/O operation.
Grant the PHY_IO privilege only to users who need it; grant
this privilege even more carefully than the LOG_IO privilege. If
this privilege is given to unqualified users who have no need for
it, the operating system and service to other users can be easily
disrupted. Such disruptions can include the destruction of information on
the system device, the destruction of user data, and the exposure
of confidential information.
The PHY_IO privilege also lets a process perform the following
tasks:
Task
Interface
Access an individual
shadow-set member unit
$ASSIGN, $QIO
Create or delete
a watchpoint
$QIO request to the SMP
watchpoint driver (WPDRIVER)
Map an LTA
device to a server/port (IO$_TTY_PORT!IO$M_LT_MAPPORT)
$QIO request to a LAT port
driver (LTDRIVER)
Issue the following
I/O requests:
Logical I/O request
Logical or virtual I/O request with IO$M_MSCPMODIFS
modifier
Physical I/O to private, non-file-structured device
$QIO
Modify the
following terminal attributes: HANGUP SET_SPEED SECURE_SERVER
SET TERMINAL or the terminal
driver (TTDRIVER) /[NO]HANGUP /[NO]SET_SPEED /[NO]SECURE_SERVER
Issue IO$_ACCESS
(diagnostic) function to DEBNA/NI device driver
$QIO request to a synchronous
communications line (XGDRIVER)
Enable Ethernet
promiscuous mode listening
Issue IO$_ACCESS (diagnostic)
function to Ethernet common driver
HP OpenVMS Guide to System Security
Security for the System Administrator
