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Roll in information from README.

gdb-4_18-branch
John Gilmore 35 years ago
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  1. 132
      gdb/doc/gdbint.texinfo

132
gdb/doc/gdbint.texinfo
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@ -81,7 +81,7 @@ When building support for a new host and/or target, much of the work you
need to do is handled by specifying configuration files;
@pxref{Config,,Adding a New Configuration}. Further work can be
divided into ``host-dependent'' (@pxref{Host,,Adding a New Host}) and
``target=dependent'' (@pxref{Target,,Adding a New Target}). The
``target-dependent'' (@pxref{Target,,Adding a New Target}). The
following discussion is meant to explain the difference between hosts
and targets.
@ -217,17 +217,31 @@ system that's already supported, you are done.
If you want to use GDB to debug programs that run on the new machine,
you have to get it to understand the machine's object files, symbol
files, and interfaces to processes. @pxref{Target}.
files, and interfaces to processes. @pxref{Target}
Add a file @file{gdb/xconfig/@var{xxx}} which specifies whatever object
files are needed as the makefile macro @samp{XDEPFILES=@dots{}}. In the
same file, specify the header file to describe @var{xxx} as
Several files control GDB's configuration for host systems:
@table @file
@item gdb/xconfig/@var{xxx}
Specifies what object files are needed when hosting on machine @var{xxx},
by defining the makefile macro @samp{XDEPFILES=@dots{}}. Also
specifies the header file which describes @var{xxx}, by defining
@samp{XM_FILE= xm-@var{xxx}.h}. You can also define @samp{CC},
@samp{REGEX} and @samp{REGEX1}, @samp{SYSV_DEFINE}, @samp{XM_CFLAGS},
etc. in there; see @file{Makefile.in}.
Create @file{gdb/xm-@var{xxx}.h} with the appropriate @code{#define}s
for your system (crib from existing @file{xm-*.h} files).
@samp{XM_ADD_FILES}, @samp{XM_CLIBS}, @samp{XM_CDEPS},
etc.; see @file{Makefile.in}.
@item gdb/xm-@var{xxx}.h
(@file{xm.h} is a link to this file, created by configure).
Contains C macro definitions describing the host system environment,
such as byte order, host C compiler and library, ptrace support,
and core file structure. Crib from existing @file{xm-*.h} files
to create a new one.
@item gdb/@var{xxx}-xdep.c
Contains any miscellaneous C code required for this machine
as a host. On some machines it doesn't exist at all.
@end table
There are some ``generic'' versions of routines that can be used by
various host systems. These can be customized in various ways by macros
@ -242,16 +256,20 @@ into @code{XDEPFILES}.
@subheading Generic Host Support Files
@table @code
@table @file
@item infptrace.c
@code{ptrace} support.
This is the low level interface to inferior processes for systems
using the Unix @code{ptrace} call in a vanilla way.
@item coredep.c:fetch_core_registers()
@item coredep.c::fetch_core_registers()
Support for reading registers out of a core file. This routine calls
@code{register_addr(}), see below.
@code{register_addr()}, see below.
Now that BFD is used to read core files, virtually all machines should
use @code{coredep.c}, and should just provide @code{fetch_core_registers} in
@code{@var{xxx}-xdep.c}.
@item coredep.c:register_addr()
@item coredep.c::register_addr()
If your @code{xm-@var{xxx}.h} file defines the macro
@code{REGISTER_U_ADDR(reg)} to be the offset within the @samp{user}
struct of a register (represented as a GDB register number),
@ -336,26 +354,66 @@ For a new target called @var{ttt}, first specify the configuration as
described in @ref{Config,,Adding a New Configuration}. If your new
target is the same as your new host, you've probably already done that.
Add a file @file{gdb/tconfig/@var{ttt}} which specifies whatever object
files are needed as the makefile macro @samp{TDEPFILES=@dots{}}. In the
same file, specify the header file to describe @var{ttt} as
@samp{TM_FILE= tm-@var{ttt}.h}. You can also define @samp{CC},
@samp{REGEX} and @samp{REGEX1}, @samp{SYSV_DEFINE}, @samp{XM_CFLAGS},
etc. in there; see @file{Makefile.in}.
Create @file{gdb/tm-@var{ttt}.h} with the appropriate @code{#define}s
for your system (crib from existing @file{tm-*.h} files).
When adding support for a new target machine, there are various areas
of support that might need change, or might be OK.
A variety of files specify attributes of the target environment:
The file @file{exec.c} defines functions for accessing files that are
@table @file
@item gdb/tconfig/@var{ttt}
Specifies what object files are needed for target @var{ttt}, by
defining the makefile macro @samp{TDEPFILES=@dots{}}.
Also specifies the header file which describes @var{ttt}, by defining
@samp{TM_FILE= tm-@var{ttt}.h}. You can also define @samp{CC},
@samp{REGEX} and @samp{REGEX1}, @samp{SYSV_DEFINE}, @samp{TM_CFLAGS},
and other Makefile variables here; see @file{Makefile.in}.
@item gdb/tm-@var{ttt}.h
(@file{tm.h} is a link to this file, created by configure).
Contains macro definitions about the target machine's
registers, stack frame format and instructions.
Crib from existing @file{tm-*.h} files when building a new one.
@item gdb/@var{ttt}-tdep.c
Contains any miscellaneous code required for this target machine.
On some machines it doesn't exist at all. Sometimes the macros
in @file{tm-@var{ttt}.h} become very complicated, so they are
implemented as functions here instead, and the macro is simply
defined to call the function.
@item gdb/exec.c
Defines functions for accessing files that are
executable on the target system. These functions open and examine an
exec file, extract data from one, write data to one, print information
about one, etc. Now that executable files are handled with BFD, every
target should be able to use the generic exec.c rather than its
own custom code.
@item gdb/@var{arch}-pinsn.c
Prints (disassembles) the target machine's instructions.
This file is usually shared with other target machines which use the
same processor, which is why it is @file{@var{arch}-pinsn.c} rather
than @file{@var{ttt}-pinsn.c}.
@item gdb/@var{arch}-opcode.h
Contains some large initialized
data structures describing the target machine's instructions.
This is a bit strange for a @file{.h} file, but it's OK since
it is only included in one place. @file{@var{arch}-opcode.h} is shared
between the debugger and the assembler, if the GNU assembler has been
ported to the target machine.
@item gdb/tm-@var{arch}.h
This often exists to describe the basic layout of the target machine's
processor chip (registers, stack, etc).
If used, it is included by @file{tm-@var{xxx}.h}. It can
be shared among many targets that use the same processor.
@item gdb/@var{arch}-tdep.c
Similarly, there are often common subroutines that are shared by all
target machines that use this particular architecture.
@end table
When adding support for a new target machine, there are various areas
of support that might need change, or might be OK.
If you are using an existing object file format (a.out or COFF),
there is probably little to be done. See @file{bfd/doc/bfd.texinfo}
for more information on writing new a.out or COFF versions.
@ -363,15 +421,9 @@ for more information on writing new a.out or COFF versions.
If you need to add a new object file format, you are beyond the scope
of this document right now. Look at the structure of the a.out
and COFF support, build a transfer vector (@code{xvec}) for your new format,
and start populating it with routines. Add it to the list in
and start populating it with routines. Add it to the list in
@file{bfd/targets.c}.
If you are adding a new existing CPU chip (e.g. m68k family), you'll
need to define an @file{@var{xarch}-opcode.h} file, a
@file{tm-@var{xarch}.h} file that gives the basic layout of the chip
(registers, stack, etc), probably an @file{@var{xarch}-tdep.c} file that
has support routines for @file{tm-@var{xarch}.h}, etc.
If you are adding a new operating system for an existing CPU chip, add a
@file{tm-@var{xos}.h} file that describes the operating system
facilities that are unusual (extra symbol table info; the breakpoint
@ -394,12 +446,14 @@ To add other languages to GDB's expression parser, follow the following steps:
This should reside in a file @file{@var{lang}-exp.y}. Routines for building
parsed expressions into a @samp{union exp_element} list are in @file{parse.c}.
Since we can't depend upon everyone having Bison, the following lines
@emph{must} be included at the top of the YACC parser:
Since we can't depend upon everyone having Bison, and YACC produces
parsers that define a bunch of global names, the following lines
@emph{must} be included at the top of the YACC parser, to prevent
the various parsers from defining the same global names:
@example
#define yyparse @var{lang}_parse
#define yylex @var{lang}_lex
#define yylex @var{lang}_lex
#define yyerror @var{lang}_error
#define yylval @var{lang}_lval
#define yychar @var{lang}_char
@ -412,10 +466,10 @@ Since we can't depend upon everyone having Bison, the following lines
#define yypgo @var{lang}_pgo
#define yyact @var{lang}_act
#define yyexca @var{lang}_exca
#define yyerrflag @var{lang}_errflag
#define yynerrs @var{lang}_nerrs
@end example
This will prevent name conflicts between the various parsers.
@item Add any evaluation routines, if necessary
If you need new opcodes (that represent the operations of the language),

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