.th CORE V 2/11/75
.sh NAME
core \*- format of core image file
.sh DESCRIPTION
UNIX
writes out a core image of a terminated
process when any of various errors occur.
See
.it "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 process's
working directory (provided it can be; normal
access controls apply).
.s3
The first 1024 bytes of the core image
are a copy of the system's per-user
data for the process, including the registers
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.
.s3
The format of the
information in the first 1024 bytes
is described by
the
.it user
structure of the system.
The important stuff not detailed therein is the locations of the registers.
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.
.s3
.lp +10 7
fpsr	0004
.lp +10 7
fr0	0006  (0006)
.lp +10 7
fr1	0036  (0022)
.lp +10 7
fr2	0046  (0026)
.lp +10 7
fr3	0056  (0032)
.lp +10 7
fr4	0016  (0012)
.lp +10 7
fr5	0026  (0016)
.lp +10 7
r0	1772
.lp +10 7
r1	1766
.lp +10 7
r2	1750
.lp +10 7
r3	1752
.lp +10 7
r4	1754
.lp +10 7
r5	1756
.lp +10 7
sp	1764
.lp +10 7
pc	1774
.lp +10 7
ps	1776
.s3
.i0
In general the debuggers
.it "db (I)"
and
.it "cdb (I)"
are sufficient to deal with core images.
.sh "SEE ALSO"
cdb (I), db (I), signal (II)