libdevinfo - device information library
cc [ flag... ] file... –ldevinfo [ library... ] #include <libdevinfo.h>
Functions in this library access device configuration information.
Device configuration data is organized as a tree of device nodes, defined as di_node_t in the libdevinfo interfaces. Each di_node_t represents a physical or logical (pseudo) device. The types of data associated with device nodes are:
data defined for all device nodes (attributes)
data defined for all multipath path nodes
data defined for all minor node data
properties specific to nodes
All device nodes have a set of common attributes, such as a node name, an instance number, and a driver binding name. Common device node attributes are accessed by calling interfaces listed on the di_binding_name(3DEVINFO) manual page. Each device node also has a physical path, which is accessed by calling di_devfs_path(3DEVINFO).
Properties provide device specific information for device configuration and usage. Properties can be defined by software (di_prop_t) or by firmware (di_prom_prop_t). One way to access each di_prop_t is to make successive calls to di_prop_next(3DEVINFO) until DI_PROP_NIL is returned. For each di_prop_t, use interfaces on the di_prop_bytes(3DEVINFO) manual page to obtain property names and values. Another way to access these properties is to call di_prop_lookup_bytes(3DEVINFO) to find the value of a property with a given name. Accessing a di_prom_prop_t is similar to accessing a di_prop_t , except that the interface names start with di_prom_prop and additional calls to di_prom_init(3DEVINFO) and di_prom_fini(3DEVINFO) are required.
Minor nodes contain information exported by the device for creating special files for the device. Each device node has 0 or more minor nodes associated with it. A list of minor nodes (di_minor_t) can be obtained by making successive calls to di_minor_next(3DEVINFO) until DI_MINOR_NIL is returned. For each minor node, di_minor_devt(3DEVINFO) and related interfaces are called to get minor node data.
In some configurations, multipath device access via a virtual host controller interface (vHCI) abstraction is possible. An example of a driver using this abstraction is scsi_vhci(7D). In such cases, devices are not directly represented as children of their physical host controller interface (pHCI) bus adapter. Instead, devices have an identity-oriented representation as a child of a vHCI. All paths leading to the same identity are represented by a common child endpoint of the vHCI called the “client” device node. The vHCI virtualizes access among the underlying pHCI physical paths. The underlying connection between vHCI-managed client endpoints and the pHCI paths to that endpoint is represented by a class of nodes called “path” nodes (di_path_t).
Each path node is associated with two device nodes: its pHCI device node, and its client device node. A list of paths associated with a specific pHCI device node can be obtained using di_path_phci_next_path(3DEVINFO), and a list of paths associated with a specific client device node can be obtained using di_path_client_next_path(3DEVINFO). These functions return DI_PATH_NIL when the end of the list of path nodes is reached.
For each path node, di_path_state(3DEVINFO) and related interfaces are called to get path node data.
Using libdevinfo involves three steps:
Creating a snapshot of the device tree
Traversing the device tree to get information of interest
Destroying the snapshot of the device tree
A snapshot of the device tree is created by calling di_init(3DEVINFO) and destroyed by calling di_fini(3DEVINFO). An application can specify the data to be included in the snapshot (full or partial tree, include or exclude properties and minor nodes) and get a handle to the root of the device tree. See di_init(3DEVINFO) for details. The application then traverses the device tree in the snapshot to obtain device configuration data.
The device tree is normally traversed through parent-child-sibling linkage. Each device node contains references to its parent, its next sibling, and the first of its children. Given the di_node_t returned from di_init(), one can find all children by first calling di_child_node(3DEVINFO), followed by successive calls to di_sibling_node(3DEVINFO) until DI_NODE_NIL is returned. By following this procedure recursively, an application can visit all device nodes contained in the snapshot. Two interfaces,The di_walk_node(3DEVINFO) and di_walk_minor(3DEVINFO) functions are provided to facilitate device tree traversal. The di_walk_node() function visits all device nodes and executes a user-supplied callback function for each node visited. The di_walk_minor() function does the same for each minor node in the device tree.
An alternative way to traverse the device tree is through the per-driver device node linkage. Device nodes contain a reference to the next device node bound to the same driver. Given the di_node_t returned from di_init(), an application can find all device nodes bound to a driver by first calling di_drv_first_node(3DEVINFO), followed by successive calls to di_drv_next_node(3DEVINFO) until DI_NODE_NIL is returned. Traversing the per-driver device node list works only when the snapshot includes all device nodes.
The shared object libdevinfo.so.1 provides the public interfaces defined below. See Intro(3) for additional information on shared object interfaces.
The following example illustrates the kind of information accessible through libdevinfo interfaces for a device node representing a hard disk (sd2):
Attributes node name: sd instance: 2 physical path: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@2,0 Properties target=2 lun=0 Minor nodes (disk partition /dev/dsk/c0t2d0s0) name: a dev_t: 0x0080010 (32/16) spectype: IF_BLK (block special) (disk partition /dev/rdsk/c0t2d0s2) name: c,raw dev_t: 0x0080012 (32/18) spectype: IF_CHR (character special)
64-bit shared object
See attributes(5) for descriptions of the following attributes:
pvs(1), devlinks(1M), prtconf(1M), Intro(3), di_binding_name(3DEVINFO), di_child_node(3DEVINFO), di_devfs_path(3DEVINFO), di_init(3DEVINFO), di_minor_devt(3DEVINFO), di_minor_next(3DEVINFO), di_path_bus_addr(3DEVINFO), di_path_client_next_path(3DEVINFO), di_path_prop_bytes(3DEVINFO), di_path_prop_lookup_bytes(3DEVINFO), di_path_prop_next(3DEVINFO), di_prom_init(3DEVINFO), di_prop_bytes(3DEVINFO), di_prop_lookup_bytes(3DEVINFO), di_prop_next(3DEVINFO), di_walk_minor(3DEVINFO), di_walk_node(3DEVINFO), attributes(5)