1 README for GAS 2 3A number of things have changed since version 1 and the wonderful 4world of gas looks very different. There's still a lot of irrelevant 5garbage lying around that will be cleaned up in time. Documentation 6is scarce, as are logs of the changes made since the last gas release. 7My apologies, and I'll try to get something useful. 8 9Unpacking and Installation - Summary 10==================================== 11 12See ../binutils/README. 13 14To build just the assembler, make the target all-gas. 15 16Documentation 17============= 18 19The GAS release includes texinfo source for its manual, which can be processed 20into `info' or `dvi' forms. 21 22The DVI form is suitable for printing or displaying; the commands for doing 23this vary from system to system. On many systems, `lpr -d' will print a DVI 24file. On others, you may need to run a program such as `dvips' to convert the 25DVI file into a form your system can print. 26 27If you wish to build the DVI file, you will need to have TeX installed on your 28system. You can rebuild it by typing: 29 30 cd gas/doc 31 make as.dvi 32 33The Info form is viewable with the GNU Emacs `info' subsystem, or the 34stand-alone `info' program, available as part of the GNU Texinfo distribution. 35To build the info files, you will need the `makeinfo' program. Type: 36 37 cd gas/doc 38 make info 39 40Specifying names for hosts and targets 41====================================== 42 43 The specifications used for hosts and targets in the `configure' 44script are based on a three-part naming scheme, but some short 45predefined aliases are also supported. The full naming scheme encodes 46three 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 55facility to list all supported host and target names or aliases. 56`configure' calls the Bourne shell script `config.sub' to map 57abbreviations to full names; you can read the script, if you wish, or 58you can use it to test your guesses on abbreviations--for example: 59 60 % sh config.sub sun4 61 sparc-sun-sunos411 62 % sh config.sub sun3 63 m68k-sun-sunos411 64 % sh config.sub decstation 65 mips-dec-ultrix42 66 % sh config.sub hp300bsd 67 m68k-hp-bsd 68 % sh config.sub i386v 69 i386-unknown-sysv 70 % sh config.sub i786v 71 Invalid configuration `i786v': machine `i786v' not recognized 72 73 74`configure' options 75=================== 76 77 Here is a summary of the `configure' options and arguments that are 78most often useful for building GAS. `configure' also has several other 79options not listed here. 80 81 configure [--help] 82 [--prefix=DIR] 83 [--srcdir=PATH] 84 [--host=HOST] 85 [--target=TARGET] 86 [--with-OPTION] 87 [--enable-OPTION] 88 89You may introduce options with a single `-' rather than `--' if you 90prefer; but you may abbreviate option names if you use `--'. 91 92`--help' 93 Print a summary of the options to `configure', and exit. 94 95`-prefix=DIR' 96 Configure the source to install programs and files under directory 97 `DIR'. 98 99`--srcdir=PATH' 100 Look for the package's source code in directory DIR. Usually 101 `configure' can determine that directory automatically. 102 103`--host=HOST' 104 Configure GAS to run on the specified HOST. Normally the 105 configure script can figure this out automatically. 106 107 There is no convenient way to generate a list of all available 108 hosts. 109 110`--target=TARGET' 111 Configure GAS for cross-assembling programs for the specified 112 TARGET. Without this option, GAS is configured to assemble .o files 113 that run on the same machine (HOST) as GAS itself. 114 115 There is no convenient way to generate a list of all available 116 targets. 117 118`--enable-OPTION' 119 These flags tell the program or library being configured to 120 configure itself differently from the default for the specified 121 host/target combination. See below for a list of `--enable' 122 options recognized in the gas distribution. 123 124`configure' accepts other options, for compatibility with configuring 125other GNU tools recursively; but these are the only options that affect 126GAS or its supporting libraries. 127 128The `--enable' options recognized by software in the gas distribution are: 129 130`--enable-targets=...' 131 This causes one or more specified configurations to be added to those for 132 which BFD support is compiled. Currently gas cannot use any format other 133 than its compiled-in default, so this option is not very useful. 134 135`--enable-bfd-assembler' 136 This causes the assembler to use the new code being merged into it to use 137 BFD data structures internally, and use BFD for writing object files. 138 For most targets, this isn't supported yet. For most targets where it has 139 been done, it's already the default. So generally you won't need to use 140 this option. 141 142Supported platforms 143=================== 144 145At this point I believe gas to be ANSI only code for most target cpu's. That 146is, there should be relatively few, if any host system dependencies. So 147porting (as a cross-assembler) to hosts not yet supported should be fairly 148easy. Porting to a new target shouldn't be too tough if it's a variant of one 149already supported. 150 151Native assembling should work on: 152 153 sun3 154 sun4 155 386bsd 156 bsd/386 157 delta (m68k-sysv from Motorola) 158 delta88 (m88k-sysv from Motorola) 159 GNU/linux 160 m68k hpux 8.0 (hpux 7.0 may be a problem) 161 vax bsd, ultrix, vms 162 hp9000s300 163 decstation 164 irix 4 165 irix 5 166 miniframe (m68k-sysv from Convergent Technologies) 167 i386-aix (ps/2) 168 hppa (hpux 4.3bsd, osf1) 169 AIX 170 unixware 171 sco 3.2v4.2 172 sco openserver 5.0 (a.k.a. 3.2v5.0 ) 173 sparc solaris 174 ns32k (netbsd, lites) 175 176I believe that gas as a cross-assembler can currently be targeted for 177most of the above hosts, plus 178 179 arm 180 decstation-bsd (a.out format, to be used in BSD 4.4) 181 ebmon29k 182 go32 (DOS on i386, with DJGPP -- old a.out version) 183 H8/300, H8/500 (Hitachi) 184 i386-aix (ps/2) 185 i960-coff 186 mips ecoff (decstation-ultrix, iris, mips magnum, mips-idt-ecoff) 187 Mitsubishi d10v and d30v 188 nindy960 189 powerpc EABI 190 SH (Hitachi) 191 sco386 192 TI tic30 and tic80 193 vax bsd or ultrix? 194 vms 195 vxworks68k 196 vxworks960 197 z8000 (Zilog) 198 199MIPS ECOFF support has been added, but GAS will not run a C-style 200preprocessor. If you want that, rename your file to have a ".S" suffix, and 201run gcc on it. Or run "gcc -xassembler-with-cpp foo.s". 202 203Support for ELF should work now for sparc, hppa, i386, alpha, m68k, 204MIPS, powerpc. 205 206Support for sequent (ns32k), tahoe, i860 may be suffering from bitrot. 207 208If you try out gas on some host or target not listed above, please let me know 209the results, so I can update the list. 210 211Compiler Support Hacks 212====================== 213 214On a few targets, the assembler has been modified to support a feature 215that is potentially useful when assembling compiler output, but which 216may confuse assembly language programmers. If assembler encounters a 217.word pseudo-op of the form symbol1-symbol2 (the difference of two 218symbols), and the difference of those two symbols will not fit in 16 219bits, the assembler will create a branch around a long jump to 220symbol1, and insert this into the output directly before the next 221label: The .word will (instead of containing garbage, or giving an 222error message) contain (the address of the long jump)-symbol2. This 223allows the assembler to assemble jump tables that jump to locations 224very far away into code that works properly. If the next label is 225more than 32K away from the .word, you lose (silently); RMS claims 226this will never happen. If the -K option is given, you will get a 227warning message when this happens. 228 229 230REPORTING BUGS IN GAS 231===================== 232 233Bugs in gas should be reported to: 234 235 bug-binutils@gnu.org. 236 237They may be cross-posted to gcc-bugs@gnu.org if they affect the use of 238gas with gcc. They should not be reported just to gcc-bugs, since not 239all of the maintainers read that list. 240 241See ../binutils/README for what we need in a bug report. 242