From: rlarndt@austin.ibm.com (Richard L. Arndt)
Subject: Item #231: Halt-Dump
Date: Mon, 06 Feb 95 16:30:51 -0600

P1275 Open Firmware Working Group Proposal -- Proposal #231 Ver <Auth-Vers#>

Title:          Halt-Dump

Author:         R. L. Arndt rlarndt@austin.ibm.com

Date:           6 Feb 95

Ed/Tech:        Technical

Synopsis:       Add mandatory support of the halt string "dump"

Doc & Version:  PowerPC processor binding -- dated: 941006

Problem:        Need mechanisms for creating a dump of selected ram upon
                OS crash.

Proposal:

The firmware shall support halt string "dump" in the following manner.
Function:
 1. The firmware shall dump the sections of main storage specified by the
dump list to the disk halt area.  NOTE: The HALT procedure may move
elements of the dump list and/or the dump areas to make room for the open
firmware code.
 2. This is followed by a reboot as defined under the "boot" halt string of
the HALT procedure.

System State at call:
 Memory:
        The dump list may be contained and may specify any range of
        storage outside of that reserved for the Halt procedure.
 Master processor:
        As specified for other halt call-back functions.
        |%r3 | -halt argument-> | 1st pointer | --> dump[0]
                                | 2nd pointer | --dump_list_____
  ______________________________________________________________]
 [__-->|   Link    |---------------...-------------->|Link=0 (end)|
       |  pointer  |-area_name--> Dump_Area_1[0]  |--|  pointer   |-
       |area length|                              |  |area  length|
       |ra    len  |      ________________________|  |ra     len  |
       |   .       |      |                          |    .       |
       |   .       |      |-> Dump_Area_Last[0]      |    .       |
       |   .       |                                 |    .       |
       |ra    len  |                                 |ra     len  |
 Slave Processors:
        In an SMP system only one processor shall call the Halt procedure
        with a halt string of "dump" all other processors shall call the
        halt procedure with the halt string "slave".  The Halt procedure
        may cause the slave processors to loop in a program that does not
        change the state of memory.
        |%r3 | -halt argument-> | 1st pointer | --> slave[0]
 IO Sub-system:
        All elements of the IO sub-system shall be in a safe state.  In a
        safe state, they shall not be transferring data to or from memory
        nor shall they cause an interrupt to any processor.
 Interrupt Sub-system:
        The processor's MSR EE=0 prior to calling the Halt procedure.
 Disk Halt partition:
        The halt partition on the IPL disk shall consist of contiguous
        blocks of storage.  The size requirement of the halt partition is
        system dependent
Disk Halt partition after dump:
        --------------------------------
        | Endian Flag                  |
        --------------------------------
        | int <number of dump areas>   |
        --------------------------------
        |int <len of DA + name string> |
        --------------------------------
        |Dump_Area_1[0] <name string>  |
        --------------------------------
        |Dump area 1's data            |
        --------------------------------
        | Pad to 4 byte boundary       |
        --------------------------------
        |int <len of DA + name string> |
        --------------------------------
        |Dump_Area_2[0] <name string>  |
        --------------------------------
        |Dump area 2's data            |
        --------------------------------
        | Pad to 4 byte boundary       |
        --------------------------------
                        .
                        .
                        .
        --------------------------------
        |int <len of DA + name string> |
        --------------------------------
        |Dump_Area_N[0] <name string>  |
        --------------------------------
        |Dump area N's data            |
        --------------------------------
        | Pad to 4 byte boundary       |
        --------------------------------



[ P1275 Item #231 -- Received: Mon Feb  6 14:32:58 PST 1995 ]