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/h-<host>.
  13
  14 Porting to a new target
  15 -----------------------
  16 Pick a name for your target. Call that <target>.
  17 You need to create <target>.c and config/mt-<target>.
  18
  19 config/mt-<target> is a Makefile fragment.
  20 The following is usually enough:
  21 DEFAULT_VECTOR=<target>_vec
  22 SELECT_ARCHITECTURES=bfd_<cpu>_arch
  23
  24 See the list of cpu types in archures.c, or "ls cpu-*.c".
  25 for more information about .mt and .mh files, see config/README.
  26
  27 The file <target>.c is the hard part.  It implements the
  28 bfd_target <target>_vec, which includes pointers to
  29 functions that do the actual <target>-specific methods.
  30
  31 Porting to a <target> that uses the a.out binary format
  32 -------------------------------------------------------
  33
  34 In this case, the include file aout-target.h probaby does most
  35 of what you need. The program gen-aout generates <target>.c for
  36 you automatically for many a.out systems.  Do:
  37         make gen-aout
  38         ./gen-aout <target> > <target>.c
  39 (This only works if you are building on the target ("native").
  40 If you must make a cross-port from scratch, copy  the most
  41 similar existing file that includes aout-target.h, and fix what is wrong.)
  42
  43 Check the parameters in <target>.c, and fix anything that is wrong.
  44 (Also let us know about it; perhaps we can improve gen-aout.c.)
  45
  46 TARGET_IS_BIG_ENDIAN_P
  47         Should be defined if <target> is big-endian.
  48
  49 N_HEADER_IN_TEXT(x)
  50         See discussion in ../include/aout/aout32.h.
  51
  52 BYTES_IN_WORD
  53         Number of bytes per word. (Usually 4 but can be 8.)
  54
  55 ARCH
  56         Number of bits per word.  (Usually 32, but can be 64.)
  57
  58 ENTRY_CAN_BE_ZERO
  59         Define if the extry point (start address of an
  60         executable program) can be 0x0.
  61
  62 TEXT_START_ADDR
  63         The address of the start of the text segemnt in
  64         virtual memory.  Normally, the same as the entry point.
  65
  66 PAGE_SIZE
  67
  68 SEGMENT_SIZE
  69         Usually, the same as the PAGE_SIZE.
  70         Alignment needed for the data segment.
  71
  72 TARGETNAME
  73         The name of the target, for run-time lookups.
  74         Usually "a.out-<target>"