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Text File | 1993-05-30 | 15.9 KB | 429 lines

-*- text -*- README for GAS 2.0 release [cribbed largely from GDB's README file] This is version 2.0 of the GNU assembler. A number of things have changed and the wonderful world of gas looks very different. There's still a lot of irrelevant garbage lying around that will be cleaned up in time. Documentation is scarce, as are logs of the changes made since the last gas release. My apologies, and I'll try to get something useful. Unpacking and Installation - Summary ==================================== In this release, the GNU assembler ("gas") sources, the generic GNU include files, the BFD ("binary file description") library, and other libraries all have directories of their own underneath the gas-2.0 directory. The idea is that a variety of GNU tools can share a common copy of these things. Configuration scripts and makefiles exist to cruise up and down this directory tree and automatically build all the pieces in the right order. When you unpack the gas-2.0.tar.z file, you'll find a directory called `gas-2.0'. To build GAS, you can just do: cd gas-2.0 ./configure make cp gas/as.new /usr/local/bin/as (or whereever) This will configure and build all the libraries as well as GAS. If `configure' can't determine your system type, specify one as its argument, e.g., sun4 or decstation. If you get compiler warnings during this stage, see the `Reporting Bugs' section below; there are a few known problems. GAS can be used as a cross-assembler, running on a machine of one type while producing object files for a machine of another type. See below. Documentation ============= The GAS release includes texinfo source for its manual, which can be processed into `info' or `dvi' forms. The DVI form is suitable for printing or displaying; the commands for doing this vary from system to system. On many systems, `lpr -d' will print a DVI file. On others, you may need to run a program such as `dvips' to convert the DVI file into a form your system can print. If you wish to build the DVI file, you will need to have TeX installed on your system. You can rebuild it by typing: cd gas-2.0/gas/doc make as.dvi The Info form is viewable with the GNU Emacs `info' subsystem, or the standalone `info' program, available as part of the GNU Texinfo distribution. To build the info files, you will need the `makeinfo' program. Type: cd gas-2.0/gas/doc make info Installing GAS ============== GAS comes with a `configure' script that automates the process of preparing GAS for installation; you can then use `make' to build the program. The GAS distribution includes all the source code you need for GAS in a single directory, the name of which is usually composed by appending the version number to `gas'. The simplest way to configure and build GAS is to run `configure' from the `gas-VERSION-NUMBER' source directory, which in this example is the `gas-2.0' directory. First switch to the `gas-VERSION-NUMBER' source directory if you are not already in it; then run `configure'. Pass the identifier for the platform on which GAS will run as an argument. For example: cd gas-2.0 ./configure HOST make where HOST is an identifier such as `sun4' or `decstation', that identifies the platform where GAS will run. Running `configure HOST' followed by `make' builds the `bfd', `opcode', and `libiberty' libraries, then `gas' itself. (Exception: For VMS, the `bfd' library is not used.) The configured source files, and the binaries, are left in the corresponding source directories. The `configure' program is a Bourne-shell (`/bin/sh') script; if your system does not recognize this automatically when you run a different shell, you may need to run `sh' on it explicitly: sh configure HOST If you run `configure' from a directory that contains source directories for multiple libraries or programs, such as the `gas-2.0' source directory for version 2.0, `configure' creates configuration files for every directory level underneath (unless you tell it not to, with the `--norecursion' option). You can run the `configure' script from any of the subordinate directories in the GAS distribution, if you only want to configure that subdirectory; but be sure to specify a path to it. For example, with version 2.0, type the following to configure only the `bfd' subdirectory: cd gas-2.0/bfd ../configure HOST Compiling GAS in another directory ================================== If you want to run GAS versions for several host or target machines, you need a different `gas' compiled for each combination of host and target. `configure' is designed to make this easy by allowing you to generate each configuration in a separate subdirectory, rather than in the source directory. If your `make' program handles the `VPATH' feature (GNU `make' does), running `make' in each of these directories builds the `gas' program specified there. To build `gas in a separate directory, run `configure' with the `--srcdir' option to specify where to find the source. (You also need to specify a path to find `configure' itself from your working directory. If the path to `configure' would be the same as the argument to `--srcdir', you can leave out the `--srcdir' option; it will be assumed.) For example, with version 2.0, you can build GAS in a separate directory for a Sun 4 like this: cd gas-2.0 mkdir ../gas-sun4 cd ../gas-sun4 ../gas-2.0/configure sun4 make When `configure' builds a configuration using a remote source directory, it creates a tree for the binaries with the same structure (and using the same names) as the tree under the source directory. In the example, you'd find the Sun 4 library `libiberty.a' in the directory `gas-sun4/libiberty', and GAS itself in `gas-sun4/gas'. One popular reason to build several GAS configurations in separate directories is to configure GAS for cross-compiling (where GAS runs on one machine--the host--while debugging programs that run on another machine--the target). You specify a cross-debugging target by giving the `--target=TARGET' option to `configure'. When you run `make' to build a program or library, you must run it in a configured directory--whatever directory you were in when you called `configure' (or one of its subdirectories). The `Makefile' that `configure' generates in each source directory also runs recursively. If you type `make' in a source directory such as `gas-2.0' (or in a separate configured directory configured with `--srcdir=PATH/gas-2.0'), you will build all the required libraries, and then build GAS. When you have multiple hosts or targets configured in separate directories, you can run `make' on them in parallel (for example, if they are NFS-mounted on each of the hosts); they will not interfere with each other. Specifying names for hosts and targets ====================================== The specifications used for hosts and targets in the `configure' script are based on a three-part naming scheme, but some short predefined aliases are also supported. The full naming scheme encodes three pieces of information in the following pattern: ARCHITECTURE-VENDOR-OS For example, you can use the alias `sun4' as a HOST argument or in a `--target=TARGET' option. The equivalent full name is `sparc-sun-sunos4'. The `configure' script accompanying GAS does not provide any query facility to list all supported host and target names or aliases. `configure' calls the Bourne shell script `config.sub' to map abbreviations to full names; you can read the script, if you wish, or you can use it to test your guesses on abbreviations--for example: % sh config.sub sun4 sparc-sun-sunos411 % sh config.sub sun3 m68k-sun-sunos411 % sh config.sub decstation mips-dec-ultrix42 % sh config.sub hp300bsd m68k-hp-bsd % sh config.sub i386v i386-unknown-sysv % sh config.sub i786v Invalid configuration `i786v': machine `i786v' not recognized `config.sub' is also distributed in the GAS source directory (`gas-2.0', for version 2.0). `configure' options =================== Here is a summary of the `configure' options and arguments that are most often useful for building GAS. `configure' also has several other options not listed here. configure [--help] [--prefix=DIR] [--srcdir=PATH] [--norecursion] [--rm] [--target=TARGET] HOST [--with-OPTION] You may introduce options with a single `-' rather than `--' if you prefer; but you may abbreviate option names if you use `--'. `--help' Display a quick summary of how to invoke `configure'. `-prefix=DIR' Configure the source to install programs and files under directory `DIR'. `--srcdir=PATH' *Warning: using this option requires GNU `make', or another `make' that implements the `VPATH' feature.* Use this option to make configurations in directories separate from the GAS source directories. Among other things, you can use this to build (or maintain) several configurations simultaneously, in separate directories. `configure' writes configuration specific files in the current directory, but arranges for them to use the source in the directory PATH. `configure' will create directories under the working directory in parallel to the source directories below PATH. `--norecursion' Configure only the directory level where `configure' is executed; do not propagate configuration to subdirectories. `--rm' Remove the configuration that the other arguments specify. `--target=TARGET' Configure GAS for cross-assembling programs for the specified TARGET. Without this option, GAS is configured to assemble .o files that run on the same machine (HOST) as GAS itself. There is no convenient way to generate a list of all available targets. `--with-OPTION' These flags tell the program or library being configured to assume the use of certain programs, or to otherwise configure themselves differently from the default for the specified host/target combination. See below for a list of `--with' options recognized in the gas-2.0 distribution. `HOST ...' Configure GAS to run on the specified HOST. There is no convenient way to generate a list of all available hosts. `configure' accepts other options, for compatibility with configuring other GNU tools recursively; but these are the only options that affect GAS or its supporting libraries. The `--with' options recognized by software in the gas-2.0 distribution are: `--with-minimal-bfd' This causes the BFD library, if it is used by the assembler, to only link in support for the specified target; by default, support for all targets known to BFD is linked in, even though the assembler generally won't be able to use them. This will probably be made a default, or replaced by a better mechanism, for gas-2.1. `--with-bfd-assembler' This causes the assembler to use the new code being merged into it to use BFD data structures internally, and use BFD for writing object files. For most targets, this isn't supported yet. See `BFD CONVERSION' in the file `gas/NOTES'. Supported platforms =================== At this point I believe gas to be ansi only code for most target cpu's. That is, there should be relatively few, if any host system dependencies. So porting (as a cross-assembler) to hosts not yet supported should be fairly easy. Porting to a new target shouldn't be too tough if it's a variant of one already supported. Native assembling should work on: sun3 sun4 386bsd bsd/386? linux m68k hpux 8.0 (hpux 7.0 may be a problem) vax bsd, ultrix, vms hp9000s300 decstation iris miniframe (m68k-sysv from Convergent Technologies) i386-aix (ps/2) For cross-assemblers, I believe hosting to work on any of the machines listed above, plus: rs6000 sun386i at least some flavors of hpux (hpux 7.0 may be a problem) most flavors of sysV I believe that gas as a cross-assembler can currently be targetted for: 386bsd bsd/386? decstation-bsd (a.out format, to be used in BSD 4.4) ebmon29k go32 (DOS on i386, with DJGPP) h8/300, h8/500 (Hitachi) hp9000/300 i386-aix (ps/2) i960-coff linux mips ecoff (decstation-ultrix, iris, mips magnum) nindy960 sco386 sun3 sun4 vax bsd or ultrix? vms vxworks68k vxworks960 z8000 (Zilog) MIPS ECOFF support has been added, but GAS will not run a C-style preprocessor. If you want that, rename your file to have a ".S" suffix, and run gcc on it. Support for ns32k, tahoe, i860, m88k may be suffering from bitrot. Support for ELF is being worked on. It should be available in version 2.2. This version does not support the IBM RS/6000. I am not aware of any work being done to support it. If you are interested in working on it, please contact me. This version does not support the HP PA/RISC running HP/UX. A modified version of gas 1.36 which does (well enough for gcc) is available by ftp from jaguar.cs.utah.edu. If you try out gas on some host or target not listed above, please let me know the results, so I can update the list. Compiler Support Hacks ====================== The assembler has been modified to support a feature that is potentially useful when assembling compiler output, but which may confuse assembly language programmers. If assembler encounters a .word pseudo-op of the form symbol1-symbol2 (the difference of two symbols), and the difference of those two symbols will not fit in 16 bits, the assembler will create a branch around a long jump to symbol1, and insert this into the output directly before the next label: The .word will (instead of containing garbage, or giving an error message) contain (the address of the long jump)-symbol2. This allows the assembler to assemble jump tables that jump to locations very far away into code that works properly. If the next label is more than 32K away from the .word, you lose (silently); RMS claims this will never happen. If the -K option is given, you will get a warning message when this happens. REPORTING BUGS IN GAS ===================== Bugs in gas should be reported to bug-gnu-utils@prep.ai.mit.edu. They may be cross-posted to bug-gcc if they affect the use of gas with gcc. They should not be reported just to bug-gcc, since I don't read that list, and therefore wouldn't see them. If you report a bug in GAS, please remember to include: A description of exactly what went wrong, and exactly what should have happened instead. The type of machine (VAX, 68020, etc) and operating system (BSD, SunOS, DYNIX, VMS, etc) GAS was running on. The configuration name(s) given to the "configure" script. The "config.status" file should have this information. The options given to GAS at run time. The actual input file that caused the problem. It is silly to report a bug in GAS without including an input file for GAS. Don't ask us to generate the file just because you made it from files you think we have access to. 1. You might be mistaken. 2. It might take us a lot of time to install things to regenerate that file. 3. We might get a different file from the one you got, and might not see any bug. To save us these delays and uncertainties, always send the input file for the program that failed. A smaller test case that demonstrates the problem is of course preferable, but be sure it is a complete input file, and that it really does demonstrate the problem; but if paring it down would cause large delays in filing the bug report, don't bother. If the input file is very large, and you are on the internet, you may want to make it avaliable for anonymous FTP instead of mailing it. If you do, include instructions for FTP'ing it in your bug report. If you expect to be contributing a large number of test cases, it would be helpful if you would look at the test suite included in the release (based on the Deja Gnu testing framework, available from the usual ftp sites) and write test cases to fit into that framework. This is certainly not required.