PORTING   [plain text]

	Preliminary Notes on Porting BFD

The 'host' is the system a tool runs *on*.
The 'target' is the system a tool runs *for*, i.e.
a tool can read/write the binaries of the target.

Porting to a new host
Pick a name for your host. Call that <host>.
(<host> might be sun4, ...)
Create a file hosts/<host>.mh.

Porting to a new target
Pick a name for your target. Call that <target>.
Call the name for your CPU architecture <cpu>.
You need to create <target>.c and config/<target>.mt,
and add a case for it to a case statements in bfd/configure.host and
bfd/config.bfd, which associates each canonical host type with a BFD
host type (used as the base of the makefile fragment names), and to the
table in bfd/configure.in which associates each target vector with
the .o files it uses.

config/<target>.mt is a Makefile fragment.
The following is usually enough:

See the list of cpu types in archures.c, or "ls cpu-*.c".
If your architecture is new, you need to add it to the tables
in bfd/archures.c, opcodes/configure.in, and binutils/objdump.c.

For more information about .mt and .mh files, see config/README.

The file <target>.c is the hard part.  It implements the
bfd_target <target>_vec, which includes pointers to
functions that do the actual <target>-specific methods.

Porting to a <target> that uses the a.out binary format

In this case, the include file aout-target.h probaby does most
of what you need. The program gen-aout generates <target>.c for
you automatically for many a.out systems.  Do:
	make gen-aout
	./gen-aout <target> > <target>.c
(This only works if you are building on the target ("native").
If you must make a cross-port from scratch, copy the most
similar existing file that includes aout-target.h, and fix what is wrong.)

Check the parameters in <target>.c, and fix anything that is wrong.
(Also let us know about it; perhaps we can improve gen-aout.c.)

	Should be defined if <target> is big-endian.

	See discussion in ../include/aout/aout64.h.

	Number of bytes per word. (Usually 4 but can be 8.)

	Number of bits per word.  (Usually 32, but can be 64.)

	Define if the extry point (start address of an
	executable program) can be 0x0.

	The address of the start of the text segemnt in
	virtual memory.  Normally, the same as the entry point.


        Usually, the same as the TARGET_PAGE_SIZE.
        Alignment needed for the data segment.

	The name of the target, for run-time lookups.
	Usually "a.out-<target>"