| 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.ac which associates each target vector with |
| the .o files it uses. |
| |
| config/<target>.mt is a Makefile fragment. |
| The following is usually enough: |
| DEFAULT_VECTOR=<target>_vec |
| SELECT_ARCHITECTURES=bfd_<cpu>_arch |
| |
| 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.ac, 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.) |
| |
| TARGET_IS_BIG_ENDIAN_P |
| Should be defined if <target> is big-endian. |
| |
| N_HEADER_IN_TEXT(x) |
| See discussion in ../include/aout/aout64.h. |
| |
| BYTES_IN_WORD |
| Number of bytes per word. (Usually 4 but can be 8.) |
| |
| ARCH |
| Number of bits per word. (Usually 32, but can be 64.) |
| |
| ENTRY_CAN_BE_ZERO |
| Define if the extry point (start address of an |
| executable program) can be 0x0. |
| |
| TEXT_START_ADDR |
| The address of the start of the text segemnt in |
| virtual memory. Normally, the same as the entry point. |
| |
| TARGET_PAGE_SIZE |
| |
| SEGMENT_SIZE |
| Usually, the same as the TARGET_PAGE_SIZE. |
| Alignment needed for the data segment. |
| |
| TARGETNAME |
| The name of the target, for run-time lookups. |
| Usually "a.out-<target>" |
| |
| Copyright (C) 2012-2020 Free Software Foundation, Inc. |
| |
| Copying and distribution of this file, with or without modification, |
| are permitted in any medium without royalty provided the copyright |
| notice and this notice are preserved. |
