X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=README;h=4423fc53821c0c62244481cd8e94d8e4c837fc4f;hp=ba9c16dbdd5f6dfb8f7b96ad719eafda11b8a02f;hb=0ecb3fde04135d76545ce55d80abea9aef465b54;hpb=02be55611d3b1c7bf4fdfcb3a9c98f621882d417

diff --git a/README b/README
index ba9c16d..4423fc5 100644
--- a/README
+++ b/README
@@ -28,6 +28,18 @@ Currently, x86 (i386, i486, i586, i686), x86 64-bit, PowerPC 32/64, S390, S390x
 and Sparcv9 32/64 are supported. Only tested on Linux so far, but should
 theoretically work on other operating systems.
 
+Alpha and ia64 architectures are supported, but depend on 4.x gcc with atomic
+builtins support.
+
+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:
+
+- gcc 3.3 and 3.4 have a bug that prevents them from generating volatile
+  accesses to offsets in a TLS structure on 32-bit x86. These versions are
+  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
+
 QUICK START GUIDE
 -----------------
 
@@ -44,19 +56,11 @@ Usage of liburcu
 
 	* #include <urcu.h>
 	* Link the application with "-lurcu".
-	* This is the preferred version of the library, both in terms of speed
-	  and flexibility. Requires a signal, typically SIGUSR1. Can be
-	  overridden with -DSIGRCU by modifying Makefile.build.inc.
-
-Usage of liburcu-mb
-
-	* #include <urcu.h>
-	* Compile any _LGPL_SOURCE code using this library with "-DRCU_MB".
-	* Link with "-lurcu-mb".
-	* This version of the urcu library does not need to
-	  reserve a signal number. RCU_MB uses full memory barriers for
-	  readers. This eliminates the need for signals but results in slower
-	  reads.
+	* This is the preferred version of the library, in terms of
+	  grace-period detection speed, read-side speed and flexibility.
+	  Dynamically detects kernel support for sys_membarrier(). Falls back
+	  on urcu-mb scheme if support is not present, which has slower
+	  read-side.
 
 Usage of liburcu-qsbr
 
@@ -68,6 +72,23 @@ Usage of liburcu-qsbr
 	  the threads are not active. It provides the fastest read-side at the
 	  expense of more intrusiveness in the application code.
 
+Usage of liburcu-mb
+
+	* #include <urcu.h>
+	* Compile any _LGPL_SOURCE code using this library with "-DRCU_MB".
+	* Link with "-lurcu-mb".
+	* This version of the urcu library uses memory barriers on the writer
+	  and reader sides. This results in faster grace-period detection, but
+	  results in slower reads.
+
+Usage of liburcu-signal
+
+	* #include <urcu.h>
+	* Compile any _LGPL_SOURCE code using this library with "-DRCU_SIGNAL".
+	* Link the application with "-lurcu-signal".
+	* Version of the library that requires a signal, typically SIGUSR1. Can
+	  be overridden with -DSIGRCU by modifying Makefile.build.inc.
+
 Usage of liburcu-bp
 
 	* #include <urcu-bp.h>
@@ -138,6 +159,14 @@ Being careful with signals
 	rcu_quiescent_state() calls, when threads are put offline and around
 	calls to synchronize_rcu(). Even then, we do not recommend it.
 
+Interaction with mutexes
+
+	One must be careful to do not cause deadlocks due to interaction of
+	synchronize_rcu() and RCU read-side with mutexes. If synchronize_rcu()
+	is called with a mutex held, this mutex (or any mutex which has this
+	mutex in its dependency chain) should not be acquired from within a RCU
+	read-side critical section.
+
 Usage of DEBUG_RCU
 
 	DEBUG_RCU is used to add internal debugging self-checks to the