Test fix: test_perthreadlock uninitialized mutex

[urcu.git] / README

diff --git a/README b/README
index a6e29c875de973ec9020cad76de9e28aa564fdf2..659de17d028c8e4ebbabed65b97ee1e3814cf99a 100644 (file)
--- a/README
+++ b/README
@@ -8,6 +8,7 @@ BUILDING
        ./configure
        make
        make install
+       ldconfig
 
        Hints:  Forcing 32-bit build:
                * CFLAGS="-m32 -g -O2" ./configure
@@ -28,7 +29,7 @@ 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.
 
-ARM depends on running a Linux kernel 2.6.15 or better.
+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:
@@ -38,8 +39,26 @@ 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.
 
 
 QUICK START GUIDE
@@ -153,7 +172,7 @@ 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
 
@@ -184,6 +203,15 @@ 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