The autopush(1M) facility configures the list of modules for a STREAMS device. It automatically pushes a prespecified list (/etc/iu.ap) of modules onto the stream when the STREAMS device is opened and the device is not already open.
The STREAMS Administrative Driver (SAD) (see the sad(7D) man page) provides an interface to the autopush mechanism. System administrators can open the SAD driver and set or get autopush information on other drivers. The SAD driver caches the list of modules to push for each driver. When the driver is opened the stream head checks the SAD's cache to determine if the device is configured to have modules pushed automatically. If an entry is found, the modules are pushed. If the device has been opened but not closed, another open does not cause the list of the prespecified modules to be pushed again.
Three options configure the module list:
Configure for each minor device (that is, a specific major and minor device number)
Configure for a range of minor devices within a major device
Configure for all minor devices within a major device
In addition, when configuring the module list, an optional anchor can be placed within the module list. See STREAMS Anchors for more information.
When the module list is cleared, a range of minor devices has to be cleared as a range and not in parts.