GLDv2 is a multi-threaded, clonable, loadable kernel module that provides support to device drivers for local area networks. Local area network (LAN) device drivers in the Oracle Solaris OS are STREAMS-based drivers that use the Data Link Provider Interface (DLPI) to communicate with network protocol stacks. These protocol stacks use the network drivers to send and receive packets on a LAN. The GLDv2 implements much of the STREAMS and DLPI functionality for a n Oracle Solaris LAN driver. The GLDv2 provides common code that many network drivers can share. Using the GLDv2 reduces duplicate code and simplifies your network driver.
For more information about GLDv2, see the gld(7D) man page.
STREAMS drivers are documented in Part II, Kernel Interface, in STREAMS Programming Guide . Specifically, see Chapter 9, “STREAMS Drivers,” in the STREAMS guide. The STREAMS framework is a message-based framework. Interfaces that are unique to STREAMS drivers include STREAMS message queue processing entry points.
The DLPI specifies an interface to the Data Link Services (DLS) of the Data Link Layer of the OSI Reference Model. The DLPI enables a DLS user to access and use any of a variety of conforming DLS providers without special knowledge of the provider's protocol. The DLPI specifies access to the DLS provider in the form of M_PROTO and M_PCPROTO type STREAMS messages. A DLPI module uses STREAMS ioctl calls to link to the MAC sub-layer. For more information about the DLPI protocol, including Oracle Solaris-specific DPLI extensions, see the dlpi(7P) man page. For general information about DLPI, see the DLPI standard at http://www.opengroup.org/pubs/catalog/c811.htm.
An Oracle Solaris network driver that is implemented using GLDv2 has two distinct parts:
Generic component. Handles STREAMS and DLPI interfaces.
Device-specific component. Handles the particular hardware device.
Indicates the driver's dependence on the GLDv2 module by linking with a dependency on misc/gld. The GLDv2 module can be found at /kernel/misc/sparcv9/gld on SPARC systems, /kernel/misc/amd64/gld on 64–bit x86 systems, and /kernel/misc/gld on 32–bit x86 systems.
Registers with GLDv2: In its attach(9E) entry point, the driver provides GLDv2 with pointers to its other entry points. GLDv2 uses these pointers to call into the gld(9E) entry point.
Calls gld(9F) functions to process data or to use some other GLDv2 service. The gld_mac_info(9S) structure is the primary data interface between GLDv2 and the device-specific driver.
GLDv2 drivers must process fully formed MAC-layer packets and must not perform logical link control (LLC) handling.
This section discusses the following topics: