gas/README

   1                 README for GAS
   2
   3 A number of things have changed since version 1 and the wonderful
   4 world of gas looks very different.  There's still a lot of irrelevant
   5 garbage lying around that will be cleaned up in time.  Documentation
   6 is scarce, as are logs of the changes made since the last gas release.
   7 My apologies, and I'll try to get something useful.
   8
   9 Unpacking and Installation - Summary
  10 ====================================
  11
  12 See ../binutils/README.
  13
  14 To build just the assembler, make the target all-gas.
  15
  16 Documentation
  17 =============
  18
  19 The GAS release includes texinfo source for its manual, which can be processed
  20 into `info' or `dvi' forms.
  21
  22 The DVI form is suitable for printing or displaying; the commands for doing
  23 this vary from system to system.  On many systems, `lpr -d' will print a DVI
  24 file.  On others, you may need to run a program such as `dvips' to convert the
  25 DVI file into a form your system can print.
  26
  27 If you wish to build the DVI file, you will need to have TeX installed on your
  28 system.  You can rebuild it by typing:
  29
  30         cd gas/doc
  31         make as.dvi
  32
  33 The Info form is viewable with the GNU Emacs `info' subsystem, or the
  34 stand-alone `info' program, available as part of the GNU Texinfo distribution.
  35 To build the info files, you will need the `makeinfo' program.  Type:
  36
  37         cd gas/doc
  38         make info
  39
  40 Specifying names for hosts and targets
  41 ======================================
  42
  43    The specifications used for hosts and targets in the `configure'
  44 script are based on a three-part naming scheme, but some short
  45 predefined aliases are also supported.  The full naming scheme encodes
  46 three pieces of information in the following pattern:
  47
  48      ARCHITECTURE-VENDOR-OS
  49
  50    For example, you can use the alias `sun4' as a HOST argument or in a
  51 `--target=TARGET' option.  The equivalent full name is
  52 `sparc-sun-sunos4'.
  53
  54    The `configure' script accompanying GAS does not provide any query
  55 facility to list all supported host and target names or aliases.
  56 `configure' calls the Bourne shell script `config.sub' to map
  57 abbreviations to full names; you can read the script, if you wish, or
  58 you can use it to test your guesses on abbreviations--for example:
  59
  60      % sh config.sub i386v
  61      i386-unknown-sysv
  62      % sh config.sub i786v
  63      Invalid configuration `i786v': machine `i786v' not recognized
  64
  65
  66 `configure' options
  67 ===================
  68
  69    Here is a summary of the `configure' options and arguments that are
  70 most often useful for building GAS.  `configure' also has several other
  71 options not listed here.
  72
  73      configure [--help]
  74                [--prefix=DIR]
  75                [--srcdir=PATH]
  76                [--host=HOST]
  77                [--target=TARGET]
  78                [--with-OPTION]
  79                [--enable-OPTION]
  80
  81 You may introduce options with a single `-' rather than `--' if you
  82 prefer; but you may abbreviate option names if you use `--'.
  83
  84 `--help'
  85      Print a summary of the options to `configure', and exit.
  86
  87 `-prefix=DIR'
  88      Configure the source to install programs and files under directory
  89      `DIR'.
  90
  91 `--srcdir=PATH'
  92      Look for the package's source code in directory DIR.  Usually
  93      `configure' can determine that directory automatically.
  94
  95 `--host=HOST'
  96      Configure GAS to run on the specified HOST.  Normally the
  97      configure script can figure this out automatically.
  98
  99      There is no convenient way to generate a list of all available
 100      hosts.
 101
 102 `--target=TARGET'
 103      Configure GAS for cross-assembling programs for the specified
 104      TARGET.  Without this option, GAS is configured to assemble .o files
 105      that run on the same machine (HOST) as GAS itself.
 106
 107      There is no convenient way to generate a list of all available
 108      targets.
 109
 110 `--enable-OPTION'
 111      These flags tell the program or library being configured to
 112      configure itself differently from the default for the specified
 113      host/target combination.  See below for a list of `--enable'
 114      options recognized in the gas distribution.
 115
 116 `configure' accepts other options, for compatibility with configuring
 117 other GNU tools recursively; but these are the only options that affect
 118 GAS or its supporting libraries.
 119
 120 The `--enable' options recognized by software in the gas distribution are:
 121
 122 `--enable-targets=...'
 123      This causes one or more specified configurations to be added to those for
 124      which BFD support is compiled.  Currently gas cannot use any format other
 125      than its compiled-in default, so this option is not very useful.
 126
 127 `--enable-bfd-assembler'
 128      This causes the assembler to use the new code being merged into it to use
 129      BFD data structures internally, and use BFD for writing object files.
 130      For most targets, this isn't supported yet.  For most targets where it has
 131      been done, it's already the default.  So generally you won't need to use
 132      this option.
 133
 134 Compiler Support Hacks
 135 ======================
 136
 137 On a few targets, the assembler has been modified to support a feature
 138 that is potentially useful when assembling compiler output, but which
 139 may confuse assembly language programmers.  If assembler encounters a
 140 .word pseudo-op of the form symbol1-symbol2 (the difference of two
 141 symbols), and the difference of those two symbols will not fit in 16
 142 bits, the assembler will create a branch around a long jump to
 143 symbol1, and insert this into the output directly before the next
 144 label: The .word will (instead of containing garbage, or giving an
 145 error message) contain (the address of the long jump)-symbol2.  This
 146 allows the assembler to assemble jump tables that jump to locations
 147 very far away into code that works properly.  If the next label is
 148 more than 32K away from the .word, you lose (silently); RMS claims
 149 this will never happen.  If the -K option is given, you will get a
 150 warning message when this happens.
 151
 152
 153 REPORTING BUGS IN GAS
 154 =====================
 155
 156 Bugs in gas should be reported to:
 157
 158    bug-binutils@gnu.org.
 159
 160 They may be cross-posted to gcc-bugs@gnu.org if they affect the use of
 161 gas with gcc.  They should not be reported just to gcc-bugs, since not
 162 all of the maintainers read that list.
 163
 164 See ../binutils/README for what we need in a bug report.
 165 \f
 166 Copyright (C) 2012-2015 Free Software Foundation, Inc.
 167
 168 Copying and distribution of this file, with or without modification,
 169 are permitted in any medium without royalty provided the copyright
 170 notice and this notice are preserved.