STREAMS/UX for the HP 9000 Reference Manual

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Differences Between STREAMS/UX and System V Release 4 STREAMS
HP-UX Changes to STREAMS/UX Drivers and Modules
High Water Mark: 2048
Low Water Mark: 128
The HP-UX sad driver device file is /dev/sad. The system administrator and
users can open /dev/sad. However, only the system administrator can
execute the SAD_SAP ioctl system call. This differs from the System V sad
driver, which is accessed through the /dev/sad/admin and /dev/sad/user
device files.
sad provides autopush functionality as described in the UNIX SVR4.2
System Files and Devices Reference manual.
echo
Major Number: 116
Module ID Number: 5000
Maximum Packet Size: INFPSZ
Minimum Packet Size: 0
High Water Mark: 2048
Low Water Mark: 128
echo is a loopback driver used by the strvf STREAMS/UX verification tool.
For more information about strvf, see Chapter 1.
sc
Module ID Number: 5002
Maximum Packet Size: INFPSZ
Minimum Packet Size: 0
High Water Mark: 2048
Low Water Mark: 128
sc provides auxiliary functions for the sad driver.