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