| 1 | Preliminary Notes on Porting BFD
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| 2 | --------------------------------
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| 3 |
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| 4 | The 'host' is the system a tool runs *on*.
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| 5 | The 'target' is the system a tool runs *for*, i.e.
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| 6 | a tool can read/write the binaries of the target.
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| 7 |
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| 8 | Porting to a new host
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| 9 | ---------------------
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| 10 | Pick a name for your host. Call that <host>.
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| 11 | (<host> might be sun4, ...)
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| 12 | Create a file hosts/<host>.mh.
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| 13 |
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| 14 | Porting to a new target
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| 15 | -----------------------
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| 16 | Pick a name for your target. Call that <target>.
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| 17 | Call the name for your CPU architecture <cpu>.
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| 18 | You need to create <target>.c and config/<target>.mt,
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| 19 | and add a case for it to a case statements in bfd/configure.host and
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| 20 | bfd/config.bfd, which associates each canonical host type with a BFD
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| 21 | host type (used as the base of the makefile fragment names), and to the
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| 22 | table in bfd/configure.in which associates each target vector with
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| 23 | the .o files it uses.
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| 24 |
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| 25 | config/<target>.mt is a Makefile fragment.
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| 26 | The following is usually enough:
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| 27 | DEFAULT_VECTOR=<target>_vec
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| 28 | SELECT_ARCHITECTURES=bfd_<cpu>_arch
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| 29 |
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| 30 | See the list of cpu types in archures.c, or "ls cpu-*.c".
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| 31 | If your architecture is new, you need to add it to the tables
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| 32 | in bfd/archures.c, opcodes/configure.in, and binutils/objdump.c.
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| 33 |
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| 34 | For more information about .mt and .mh files, see config/README.
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| 35 |
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| 36 | The file <target>.c is the hard part. It implements the
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| 37 | bfd_target <target>_vec, which includes pointers to
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| 38 | functions that do the actual <target>-specific methods.
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| 39 |
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| 40 | Porting to a <target> that uses the a.out binary format
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| 41 | -------------------------------------------------------
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| 42 |
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| 43 | In this case, the include file aout-target.h probaby does most
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| 44 | of what you need. The program gen-aout generates <target>.c for
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| 45 | you automatically for many a.out systems. Do:
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| 46 | make gen-aout
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| 47 | ./gen-aout <target> > <target>.c
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| 48 | (This only works if you are building on the target ("native").
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| 49 | If you must make a cross-port from scratch, copy the most
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| 50 | similar existing file that includes aout-target.h, and fix what is wrong.)
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| 51 |
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| 52 | Check the parameters in <target>.c, and fix anything that is wrong.
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| 53 | (Also let us know about it; perhaps we can improve gen-aout.c.)
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| 54 |
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| 55 | TARGET_IS_BIG_ENDIAN_P
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| 56 | Should be defined if <target> is big-endian.
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| 57 |
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| 58 | N_HEADER_IN_TEXT(x)
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| 59 | See discussion in ../include/aout/aout64.h.
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| 60 |
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| 61 | BYTES_IN_WORD
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| 62 | Number of bytes per word. (Usually 4 but can be 8.)
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| 63 |
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| 64 | ARCH
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| 65 | Number of bits per word. (Usually 32, but can be 64.)
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| 66 |
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| 67 | ENTRY_CAN_BE_ZERO
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| 68 | Define if the extry point (start address of an
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| 69 | executable program) can be 0x0.
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| 70 |
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| 71 | TEXT_START_ADDR
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| 72 | The address of the start of the text segemnt in
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| 73 | virtual memory. Normally, the same as the entry point.
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| 74 |
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| 75 | TARGET_PAGE_SIZE
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| 76 |
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| 77 | SEGMENT_SIZE
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| 78 | Usually, the same as the TARGET_PAGE_SIZE.
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| 79 | Alignment needed for the data segment.
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| 80 |
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| 81 | TARGETNAME
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| 82 | The name of the target, for run-time lookups.
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| 83 | Usually "a.out-<target>"
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