hpux 10.20 - pdc (1)
NAME
pdc - processor-dependent code (firmware)
DESCRIPTION
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 series as described below.
Series 800 Behavior
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 a series of decimal numbers each suffixed by
'/', indicating bus converters, followed by a series of decimal
numbers separated by '.', indicating the various card and slot numbers
and addresses. The first number, not specifying a bus converter, is
the MID-BUS module number (that is, slot number times four) and
followed by the CIO slot number. If the CIO slot contains an HP-IB
card, the next number is the HP-IB address, followed by the unit
number of the device if the device supports units. If the CIO slot
contains a terminal card, the next number is the port number, which
must be zero for the console.
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
through the MID-BUS modules and CIO slots to find a bootable medium.
Currently, autosearch is only implemented on the model 825.
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.
Series 700 Behavior
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 vary according to hardware model.
If autoboot and autosearch (see isl(1M)) are enabled, pdc waits for
approximately 10 seconds during which time the operator can override
the autoboot sequence pressing and holding the ESC (escape) key on the
console.
The system then begins a search for potentially bootable devices. 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 mnenomic.
+ 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
The search of potentially bootable devices can be aborted by pressing
and holding the escape key. The search for device contents can also
be aborted by pressing and holding the escape key.
If the operator does not interrupt the search process, pdc initializes
and reads isl from the Primary Boot Path.
If the autoboot sequence is unsuccessful, overridden by the operator,
or not enabled in the first place, pdc executes the device search and
enters the menu described above.
The Primary Boot, Alternate Boot, and Console Paths as well as
autoboot and autosearch enable can be modified via isl or at the pdc
boot administration level.
SEE ALSO
boot(1M), hpuxboot(1M), isl(1M).