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HP-UX Reference > P


PA-RISC Systems Only
HP-UX 11i Version 3: February 2007

Technical documentation

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pdc — processor-dependent code (firmware)


pdc is the firmware that implements all processor-dependent functionality, including initialization and self-test of the processor. Upon completion, it loads and transfers control to the initial system loader (isl(1M)). Firmware behavior varies somewhat, depending on the hardware as described below.

To load isl from an external medium, pdc must know the particular device on which isl resides. Typically the device is identified by the Primary Boot Path that is maintained by pdc in Stable Storage. A path specification is an I/O subsystem mnemonic that varies according to hardware model.

When the processor is reset after initialization and self-test complete, pdc reads the Console Path from Stable Storage, and attempts to initialize the console device. If the initialization fails, pdc attempts to find and initialize a console device. Algorithms used to find a console device are model-dependent. pdc then announces the Primary Boot, Alternate Boot, and Console Paths.

If autoboot (see isl(1M)) is enabled, pdc provides a 10-second delay, during which time the operator can override the autoboot sequence by typing any character on the console. If the operator does not interrupt this process, pdc initializes and reads isl from the Primary Boot Path. On models that support autosearch, if this path is not valid and autosearch (see isl(1M)) is enabled, pdc then searches to find a bootable medium.

If allowed to complete, a list of potentially bootable devices is displayed, labeled with abbreviated path identifiers (P0, P1, etc). A simple menu is then displayed where the user can:

  • Boot a specific device, using the abbreviated path identifier, or the full mnemonic.

  • Start a device search where the contents are searched for IPL images (note the first search only identified devices and did not check the contents).

  • Enter the boot administration level.

  • Exit the menu and return to autobooting

  • Get help on choices

If the autoboot sequence is unsuccessful, overridden by the operator, or not enabled in the first place, pdc interactively prompts the operator for the Boot Path to use. Any required path components that are not supplied default to zero.

The Primary Boot, Alternate Boot, and Console Paths as well as autoboot and autosearch enable can be modified via isl.


boot(1M), isl(1M).

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