-*- Text -*- This is a first ***draft*** of a description of what symbols should be present in CL:*FEATURES* for various platforms. A possible future direction of this documentation might be a CDR document, if it turns out to be a good idea. (Making the language of this document much more precise will be necessary then.) We will start by limiting ourselves to OS, CPU and endianness features on Windows and POSIX platforms. There are various possible implementation strategies ranging from null implementations (when the host Lisp already pushes the wanted feature) to using FFI (e.g. calling uname() to grab system information. ============= Specification * ENDIANNESS Either :LITTLE-ENDIAN or :BIG-ENDIAN should present in *FEATURES*. For the time being, we will not concern ourselves with other orderings, switchable endianness, etc. * OPERATING SYSTEM On Windows, :WINDOWS should be present in *FEATURES*. On POSIX systems, the "sysname" information from uname(3) should be used to push the appropriate symbol to *FEATURES* by upcasing that string (or downcasing for the "modern" lisps) and interning it in the keyword package. Examples: :DARWIN :LINUX :NETBSD :OPENBSD :FREEBSD For convenience, :UNIX should be pushed when running on POSIX/UNIX-like operating system (that doesn't include Windows) and :BSD should be present when running on BSD-based systems (that includes Darwin) [add :MACH too?] * CPU These features should be mutually exclusive: :X86 :X86-64 :PPC :PPC64 :MIPS :ALPHA :SPARC :SPARC64 :HPPA :HPPA64 [add more ...] [note: it's debatable whether :X86 shouldn't also be exported on x86-64, and :PPC on ppc64. SCL does that, SBCL doesn't. Other ways to handle, for example, the x86/x86-64 case would be to export something like :PC386 in both cases or have an additional :X86-32. Or finally, have just :X86, :PPC, etc, and add :32-BIT-CPU and :64-BIT-CPU features.] ======================= Unreferenced References "CLHS: Variable *FEATURES*" "Maintaining Portable Lisp Programs", by Christophe Rhodes