projects / deliverable / binutils-gdb.git / blame
| Commit | Line | Data |
|---|---|---|
| 5f9a2245 DM |
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>" |