bfd/PORTING

   1         Preliminary Notes on Porting BFD
   2         --------------------------------
   3
   4 The 'host' is the system a tool runs *on*.
   5 The 'target' is the system a tool runs *for*, i.e.
   6 a tool can read/write the binaries of the target.
   7
   8 Porting to a new host
   9 ---------------------
  10 Pick a name for your host. Call that <host>.
  11 (<host> might be sun4, ...)
  12 Create a file hosts/<host>.mh.
  13
  14 Porting to a new target
  15 -----------------------
  16 Pick a name for your target. Call that <target>.
  17 Call the name for your CPU architecture <cpu>.
  18 You need to create <target>.c and config/<target>.mt,
  19 and add a case for it to a case statements in bfd/configure.host and
  20 bfd/config.bfd, which associates each canonical host type with a BFD
  21 host type (used as the base of the makefile fragment names), and to the
  22 table in bfd/configure.ac which associates each target vector with
  23 the .o files it uses.
  24
  25 config/<target>.mt is a Makefile fragment.
  26 The following is usually enough:
  27 DEFAULT_VECTOR=<target>_vec
  28 SELECT_ARCHITECTURES=bfd_<cpu>_arch
  29
  30 See the list of cpu types in archures.c, or "ls cpu-*.c".
  31 If your architecture is new, you need to add it to the tables
  32 in bfd/archures.c, opcodes/configure.ac, and binutils/objdump.c.
  33
  34 For more information about .mt and .mh files, see config/README.
  35
  36 The file <target>.c is the hard part.  It implements the
  37 bfd_target <target>_vec, which includes pointers to
  38 functions that do the actual <target>-specific methods.
  39
  40 Porting to a <target> that uses the a.out binary format
  41 -------------------------------------------------------
  42
  43 In this case, the include file aout-target.h probaby does most
  44 of what you need. The program gen-aout generates <target>.c for
  45 you automatically for many a.out systems.  Do:
  46         make gen-aout
  47         ./gen-aout <target> > <target>.c
  48 (This only works if you are building on the target ("native").
  49 If you must make a cross-port from scratch, copy the most
  50 similar existing file that includes aout-target.h, and fix what is wrong.)
  51
  52 Check the parameters in <target>.c, and fix anything that is wrong.
  53 (Also let us know about it; perhaps we can improve gen-aout.c.)
  54
  55 TARGET_IS_BIG_ENDIAN_P
  56         Should be defined if <target> is big-endian.
  57
  58 N_HEADER_IN_TEXT(x)
  59         See discussion in ../include/aout/aout64.h.
  60
  61 BYTES_IN_WORD
  62         Number of bytes per word. (Usually 4 but can be 8.)
  63
  64 ARCH
  65         Number of bits per word.  (Usually 32, but can be 64.)
  66
  67 ENTRY_CAN_BE_ZERO
  68         Define if the extry point (start address of an
  69         executable program) can be 0x0.
  70
  71 TEXT_START_ADDR
  72         The address of the start of the text segemnt in
  73         virtual memory.  Normally, the same as the entry point.
  74
  75 TARGET_PAGE_SIZE
  76
  77 SEGMENT_SIZE
  78         Usually, the same as the TARGET_PAGE_SIZE.
  79         Alignment needed for the data segment.
  80
  81 TARGETNAME
  82         The name of the target, for run-time lookups.
  83         Usually "a.out-<target>"
  84 \f
  85 Copyright (C) 2012-2020 Free Software Foundation, Inc.
  86
  87 Copying and distribution of this file, with or without modification,
  88 are permitted in any medium without royalty provided the copyright
  89 notice and this notice are preserved.