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a2c5833233
The result of running etc/update-copyright.py --this-year, fixing all the files whose mode is changed by the script, plus a build with --enable-maintainer-mode --enable-cgen-maint=yes, then checking out */po/*.pot which we don't update frequently. The copy of cgen was with commit d1dd5fcc38ead reverted as that commit breaks building of bfp opcodes files.
90 lines
3.0 KiB
Plaintext
90 lines
3.0 KiB
Plaintext
Preliminary Notes on Porting BFD
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--------------------------------
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The 'host' is the system a tool runs *on*.
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The 'target' is the system a tool runs *for*, i.e.
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a tool can read/write the binaries of the target.
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Porting to a new host
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---------------------
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Pick a name for your host. Call that <host>.
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(<host> might be sun4, ...)
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Create a file hosts/<host>.mh.
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Porting to a new target
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-----------------------
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Pick a name for your target. Call that <target>.
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Call the name for your CPU architecture <cpu>.
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You need to create <target>.c and config/<target>.mt,
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and add a case for it to a case statements in bfd/configure.host and
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bfd/config.bfd, which associates each canonical host type with a BFD
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host type (used as the base of the makefile fragment names), and to the
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table in bfd/configure.ac which associates each target vector with
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the .o files it uses.
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config/<target>.mt is a Makefile fragment.
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The following is usually enough:
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DEFAULT_VECTOR=<target>_vec
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SELECT_ARCHITECTURES=bfd_<cpu>_arch
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See the list of cpu types in archures.c, or "ls cpu-*.c".
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If your architecture is new, you need to add it to the tables
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in bfd/archures.c, opcodes/configure.ac, and binutils/objdump.c.
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For more information about .mt and .mh files, see config/README.
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The file <target>.c is the hard part. It implements the
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bfd_target <target>_vec, which includes pointers to
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functions that do the actual <target>-specific methods.
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Porting to a <target> that uses the a.out binary format
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-------------------------------------------------------
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In this case, the include file aout-target.h probaby does most
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of what you need. The program gen-aout generates <target>.c for
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you automatically for many a.out systems. Do:
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make gen-aout
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./gen-aout <target> > <target>.c
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(This only works if you are building on the target ("native").
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If you must make a cross-port from scratch, copy the most
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similar existing file that includes aout-target.h, and fix what is wrong.)
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Check the parameters in <target>.c, and fix anything that is wrong.
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(Also let us know about it; perhaps we can improve gen-aout.c.)
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TARGET_IS_BIG_ENDIAN_P
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Should be defined if <target> is big-endian.
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N_HEADER_IN_TEXT(x)
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See discussion in ../include/aout/aout64.h.
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BYTES_IN_WORD
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Number of bytes per word. (Usually 4 but can be 8.)
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ARCH
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Number of bits per word. (Usually 32, but can be 64.)
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ENTRY_CAN_BE_ZERO
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Define if the extry point (start address of an
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executable program) can be 0x0.
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TEXT_START_ADDR
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The address of the start of the text segemnt in
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virtual memory. Normally, the same as the entry point.
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TARGET_PAGE_SIZE
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SEGMENT_SIZE
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Usually, the same as the TARGET_PAGE_SIZE.
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Alignment needed for the data segment.
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TARGETNAME
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The name of the target, for run-time lookups.
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Usually "a.out-<target>"
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Copyright (C) 2012-2022 Free Software Foundation, Inc.
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Copying and distribution of this file, with or without modification,
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are permitted in any medium without royalty provided the copyright
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notice and this notice are preserved.
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