System interface calls and use of header files should conform to the XPG4 standards. This ensures portability to other platforms meeting the same standards.
The following table lists the standard set of services available to TU developers. Using only these services provides portability of TUs to other platforms where this diagnostic infrastructure is supported. See "Diagnostic Kernel Extension Interfaces" for more information on these functions, their input parameters, and the function prototypes.
| Function Name | Description | Usable by: |
| pdiag_open | Opens a device for testing | TU |
| pdiag_close | Frees up a device after testing | TU |
| pdiag_dd_read | Perform read operation to a device | TU, Interrupt |
| pdiag_dd_write | Perform write operation to a device | TU, Interrupt |
| pdiag_dd_dma_setup | Initializes, pins, and cross-memory attaches user buffer for a dma operation | TU |
| pdiag_dd_dma_enable | Enables/disables a dma operation | TU |
| pdiag_dd_dma_complete | Unpins the dma user buffer and detaches the cross-memory descriptor | TU |
| pdiag_dd_watch_for_interrupt | Waits for device interrupt to occur, or until a specified timeout is reached | TU |
| pdiag_dd_interrupt_notify | Notifies waiting test unit that an interrupt has been received | Interrupt |
| pdiag_diagnose_state | Places device under test into a testable state | TU |
| pdiag_restore_state | Places device under test into original state before testing | TU |
| pdiag_cs_open | Open/Initialize configuration data services | TU |
| pdiag_cs_close | Close/Terminate configuration data services | TU |
| pdiag_cs_get_attr | Obtain device attribute value | TU |
| pdiag_cs_free_attr | Free storage that was allocated by pdiag_cs_get_attr | TU |
| findmcode | Locate specific microcode file for loading (works under AIX only) | TU |