The PHY_IO privilege lets the user's process execute the QueueI/O Request ($QIO) system service to perform physical-level I/Ooperations.
Usually, process I/O requests are handled indirectly by useof an I/O package such as OpenVMS Record Management Services (RMS).However, to increase their control over I/O operations and to improvethe efficiency of their applications, skilled users sometimes preferto handle directly the interface between their process and a systemI/O driver program. They can do this by executing the $QIO systemservice; in many instances, the operation called for is a physical-levelI/O operation.
Grant the PHY_IO privilege only to users who need it; grantthis privilege even more carefully than the LOG_IO privilege. Ifthis privilege is given to unqualified users who have no need forit, the operating system and service to other users can be easilydisrupted. Such disruptions can include the destruction of information onthe system device, the destruction of user data, and the exposureof confidential information.
The PHY_IO privilege also lets a process perform the followingtasks:
Task
Interface
Access an individualshadow-set member unit
$ASSIGN, $QIO
Create or deletea watchpoint
$QIO request to the SMPwatchpoint driver (WPDRIVER)
Map an LTAdevice to a server/port (IO$_TTY_PORT!IO$M_LT_MAPPORT)
$QIO request to a LAT portdriver (LTDRIVER)
Issue the followingI/O requests:
Logical I/O request
Logical or virtual I/O request with IO$M_MSCPMODIFSmodifier
Physical I/O to private, non-file-structured device
HP OpenVMS Guide to System Security
Security for the System Administrator
