| 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) 2012-2018 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. |