; :high-security
; :high-security-support
- ;; multiprocessing support
+ ;; low-level thread primitives support
;;
- ;; This is not maintained or tested in current SBCL. I haven't gone out
- ;; of my way to break it, but since it's derived from an old version of
- ;; CMU CL where multiprocessing was pretty shaky, it's likely to be very
- ;; flaky now.
- ;; :MP enables multiprocessing
- ;; :MP-I486 is used, only within the multiprocessing code, to control
- ;; what seems to control processor-version-specific code. It's
- ;; probably for 486 or later, i.e. could be set as long as
- ;; you know you're not running on a 386, but it doesn't seem
- ;; to be documented anywhere, so that's just a guess.
- ; :mp
- ; :mp-i486
+ ;; As of SBCL 0.8, this is only supposed to work in x86 Linux, on which
+ ;; system it's implemented using clone(2) and the %fs segment register.
+ ;; Note that no consistent effort to audit the SBCL library code for
+ ;; thread safety has been performed, so caveat executor.
+ ; :sb-thread
+ ;; Kernel support for futexes (so-called "fast userspace mutexes") is
+ ;; available in Linux 2.6 and some versions of 2.4 (Red Hat vendor
+ ;; kernels, possibly other vendors too). We can take advantage of
+ ;; these to do faster and probably more reliable mutex and condition
+ ;; variable support. An SBCL built with this feature will fall back
+ ;; to the old system if the futex() syscall is not available at
+ ;; runtime
+ ; :sb-futex
+
;; This affects the definition of a lot of things in bignum.lisp. It
;; doesn't seem to be documented anywhere what systems it might apply
;; to. It doesn't seem to be needed for X86 systems anyway.
; :32x16-divide
- ;; This is probably true for some processor types, but not X86. It
- ;; affects a lot of floating point code.
- ; :negative-zero-is-not-zero
-
;; This is set in classic CMU CL, and presumably there it means
;; that the floating point arithmetic implementation
;; conforms to IEEE's standard. Here it definitely means that the
;; in the *FEATURES* list
;;
+ ;; Any target feature which affects binary compatibility of fasl files
+ ;; needs to be recorded in *FEATURES-POTENTIALLY-AFFECTING-FASL-FORMAT*
+ ;; (elsewhere).
+
;; notes on the :NIL and :IGNORE features:
;;
;; #+NIL is used to comment out forms. Occasionally #+IGNORE is used
;; any Sun UltraSPARC (possibly also non-Ultras -- currently untested)
;; :ppc
;; any PowerPC CPU
- ;;
- ;; (No other CPUs are supported by SBCL as of 0.7.5, but MIPS or HPPA
- ;; support could be ported from CMU CL if anyone is sufficiently
- ;; motivated to do so, or if you're *really* motivated, you could
- ;; write a port from scratch for a new CPU architecture.)
- ;;
+ ;; :hppa
+ ;; any PA-RISC CPU
+ ;; :mips
+ ;; any MIPS CPU (in little-endian mode with :little-endian -- currently
+ ;; untested)
+ ;;
;; (CMU CL also had a :pentium feature, which affected the definition
;; of some floating point vops. It was present but not enabled or
;; documented in the CMU CL code that SBCL is derived from, and has
;; with the SunOS kernel.
;; :osf1 = We're intended to run under Tru64 (aka Digital Unix
;; aka OSF/1).
- ;; (No others are supported by SBCL as of 0.7.5, but :hpux or
- ;; :irix support could be ported from CMU CL if anyone is
- ;; sufficiently motivated to do so, and it'd even be possible,
- ;; though harder, to port the system to Microsoft Windows.)
+ ;; (No others are supported by SBCL as of 0.7.5, but :hpux or :irix
+ ;; support could be ported from CMU CL if anyone is sufficiently
+ ;; motivated to do so, and it'd even be possible, though harder, to
+ ;; port the system to Microsoft Windows or MacOS X.)
)