X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=README;h=81afe0e2757c8bceabef7c50ff4102d0600aa8d3;hp=44a4bf574876ec222d00f7fa6123ccd88f3086d0;hb=edac6b69ad8b690437c4624cebb7eef465a09a7e;hpb=e197ac6f111ac509f2bd0fef16c041254494a0de

diff --git a/README b/README
index 44a4bf5..81afe0e 100644
--- a/README
+++ b/README
@@ -22,14 +22,17 @@ BUILDING
 		Forcing a 32-bit build for Sparcv9 (typical for Sparc v9)
 		* CFLAGS="-m32 -Wa,-Av9a -g -O2" ./configure
 
+
 ARCHITECTURES SUPPORTED
 -----------------------
 
-Currently, x86 (i386, i486, i586, i686), x86 64-bit, PowerPC 32/64, S390, S390x,
-ARM, Alpha, ia64 and Sparcv9 32/64 are supported. Only tested on Linux so
-far, but should theoretically work on other operating systems.
+Currently, Linux x86 (i386, i486, i586, i686), x86 64-bit, PowerPC 32/64,
+S390, S390x, ARM, Alpha, ia64 and Sparcv9 32/64 are supported. Tested on
+Linux, FreeBSD 8.2/9.0, and Cygwin. Should also work on: Android, NetBSD 5,
+OpenBSD, Darwin (more testing needed before claiming support for these OS).
 
-ARM depends on running a Linux kernel 2.6.15 or better.
+Linux ARM depends on running a Linux kernel 2.6.15 or better, GCC 4.4 or
+better.
 
 The gcc compiler versions 3.3, 3.4, 4.0, 4.1, 4.2, 4.3, 4.4 and 4.5 are
 supported, with the following exceptions:
@@ -39,8 +42,42 @@ supported, with the following exceptions:
   therefore not compatible with liburcu on x86 32-bit (i386, i486, i586, i686).
   The problem has been reported to the gcc community:
     http://www.mail-archive.com/gcc-bugs@gcc.gnu.org/msg281255.html
-- Alpha, ia64 and ARM architectures depend on 4.x gcc with atomic builtins
-  support.
+- gcc 3.3 cannot match the "xchg" instruction on 32-bit x86 build.
+  See: http://kerneltrap.org/node/7507
+- Alpha, ia64 and ARM architectures depend on gcc 4.x with atomic builtins
+  support. For ARM this was introduced with gcc 4.4:
+    http://gcc.gnu.org/gcc-4.4/changes.html
+
+For developers using the git tree:
+
+This source tree is based on the autotools suite from GNU to simplify
+portability. Here are some things you should have on your system in order to
+compile the git repository tree :
+
+- GNU autotools (automake >=1.10, autoconf >=2.50, autoheader >=2.50)
+  (make sure your system wide "automake" points to a recent version!)
+- GNU Libtool >=2.2
+  (for more information, go to http://www.gnu.org/software/autoconf/)
+
+If you get the tree from the repository, you will need to use the "bootstrap"
+script in the root of the tree. It calls all the GNU tools needed to prepare the
+tree configuration.
+
+Test scripts provided in the tests/ directory of the source tree depend
+on "bash" and the "seq" program.
+
+
+API
+---
+
+See the relevant API documentation files in doc/. The APIs provided by
+Userspace RCU are, by prefix:
+
+- rcu_ : Read-Copy Update
+- cmm_ : Concurrent Memory Model
+- caa_ : Concurrent Architecture Abstraction
+- cds_ : Concurrent Data Structures
+- uatomic_: Userspace Atomic
 
 
 QUICK START GUIDE
@@ -154,7 +191,7 @@ Usage of urcu-call-rcu
 	  grace periods.  A number of additional functions are provided
 	  to manage the helper threads used by call_rcu(), but reasonable
 	  defaults are used if these additional functions are not invoked.
-	  See API.txt for more details.
+	  See rcu-api.txt in userspace-rcu documentation for more details.
 
 Being careful with signals
 
@@ -166,11 +203,12 @@ Being careful with signals
 	signal(7). The liburcu-mb and liburcu-qsbr versions of the Userspace RCU
 	library do not require any signal.
 
-	Read-side critical sections are allowed in a signal handler with
-	liburcu and liburcu-mb. Be careful, however, to disable these signals
+	Read-side critical sections are allowed in a signal handler,
+	except those setup with sigaltstack(2), with liburcu and
+	liburcu-mb. Be careful, however, to disable these signals
 	between thread creation and calls to rcu_register_thread(), because a
-	signal handler nesting on an unregistered thread would not be allowed to
-	call rcu_read_lock().
+	signal handler nesting on an unregistered thread would not be
+	allowed to call rcu_read_lock().
 
 	Read-side critical sections are _not_ allowed in a signal handler with
 	liburcu-qsbr, unless signals are disabled explicitly around each
@@ -185,6 +223,15 @@ Interaction with mutexes
 	mutex in its dependency chain) should not be acquired from within a RCU
 	read-side critical section.
 
+	This is especially important to understand in the context of the
+	QSBR flavor: a registered reader thread being "online" by
+	default should be considered as within a RCU read-side critical
+	section unless explicitly put "offline". Therefore, if
+	synchronize_rcu() is called with a mutex held, this mutex, as
+	well as any mutex which has this mutex in its dependency chain
+	should only be taken when the RCU reader thread is "offline"
+	(this can be performed by calling rcu_thread_offline()).
+
 Usage of DEBUG_RCU
 
 	DEBUG_RCU is used to add internal debugging self-checks to the