--- scheme-scheduling.texi.~1.14.~	2003-07-24 10:12:43.000000000 +1000
+++ scheme-scheduling.texi	2003-12-05 09:24:37.000000000 +1000
@@ -280,21 +280,12 @@
 @section Threads
 @cindex threads
 @cindex Guile threads
address@hidden POSIX threads
 
address@hidden: this chapter was written for Cygnus Guile and has not yet
-been updated for the Guile 1.x release.]}
-
-Here is a the reference for Guile's threads.  In this chapter I simply
-quote verbatim Tom Lord's description of the low-level primitives
-written in C (basically an interface to the POSIX threads library) and
-Anthony Green's description of the higher-level thread procedures
-written in scheme.
address@hidden posix threads
address@hidden Lord, Tom
address@hidden Green, Anthony
-
-When using Guile threads, keep in mind that each guile thread is
-executed in a new dynamic root.
+Guile threads are implemented using POSIX threads, they run
+pre-emptively and concurrently through both Scheme code and system
+calls.  The only exception is for garbage collection, where all
+threads must rendezvous.
 
 @menu
 * Low level thread primitives::  
@@ -450,6 +441,43 @@
 higher level threads.  By reimplementing them, you can adapt Guile to
 different low-level thread implementations.
 
+C code in a thread must call a libguile function periodically.  When
+one thread finds garbage collection is required, it waits for all
+threads to rendezvous before doing that gc.  Such a rendezvous is
+checked within libguile functions.  If C code wants to sleep or block
+in a thread it should use one of the libguile functions provided.
+
+Only threads created by Guile can use the libguile functions.  Threads
+created directly with say @code{pthread_create} are unknown to Guile
+and they cannot call libguile.  The stack in such foreign threads is
+not scanned during GC, so @code{SCM} values generally cannot be held
+there.
+
address@hidden  FIXME:
address@hidden
address@hidden  Describe SCM_TICK which can be called if no other libguile
address@hidden  function is being used by a C function.
address@hidden
address@hidden  Describe "Guile mode", which a thread can enter and exit.  There
address@hidden  are no functions for doing this yet.
address@hidden
address@hidden  When in guile mode a thread can call libguile, is subject to the
address@hidden  tick rule, and its stack is scanned.  When not in guile mode it
address@hidden  cannot call libguile, it doesn't have to tick, and its stack is
address@hidden  not scanned.  The strange guile control flow things like
address@hidden  exceptions, continuations and asyncs only occur when in guile
address@hidden  mode.
address@hidden
address@hidden  When guile mode is exited, the portion of the stack allocated
address@hidden  while it was in guile mode is still scanned.  This portion may not
address@hidden  be modified when outside guile mode.  The stack ends up
address@hidden  partitioned into alternating guile and non-guile regions.
address@hidden
address@hidden  Leaving guile mode is convenient when running an extended
address@hidden  calculation not involving guile, since one doesn't need to worry
address@hidden  about SCM_TICK calls.
+
+
 @deftp {C Data Type} scm_t_thread
 This data type represents a thread, to be used with scm_thread_create,
 etc.