CORE(V)                      2/11/75                      CORE(V)



NAME
     core - format of core image file

DESCRIPTION
     UNIX  writes  out  a core image of a terminated process when
     any of various errors occur.  See signal(II) for  the  list
     of  reasons;  the most common are memory violations, illegal
     instructions, bus errors, and user-generated  quit  signals.
     The core image is called ``core'' and is written in the pro-
     cess's working directory (provided it can be; normal  access
     controls apply).

     The  first  1024  bytes  of the core image are a copy of the
     system's per-user data for the process, including the regis-
     ters  as  they were at the time of the fault.  The remainder
     represents the actual contents of the user's core area  when
     the  core  image was written.  If the text segment is write-
     protected and shared, it is not dumped; otherwise the entire
     address space is dumped.

     The format of the information in the first 1024 bytes is de-
     scribed by the user structure of the system.  The  important
     stuff  not  detailed  therein is the locations of the regis-
     ters.  Here are their offsets.   The  parenthesized  numbers
     for  the  floating  registers are used if the floating-point
     hardware is in single precision mode, as  indicated  in  the
     status register.

        fpsr   0004
        fr0    0006  (0006)
        fr1    0036  (0022)
        fr2    0046  (0026)
        fr3    0056  (0032)
        fr4    0016  (0012)
        fr5    0026  (0016)
        r0     1772
        r1     1766
        r2     1750
        r3     1752
        r4     1754
        r5     1756
        sp     1764
        pc     1774
        ps     1776

     In  general  the debuggers db(I) and cdb(I) are sufficient
     to deal with core images.

SEE ALSO
     cdb(I), db(I), signal(II)







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