-Currently, x86 (only P6+), x86 64, PowerPC 32/64 and S390 are
-supported. The current use of sys_futex() makes it Linux-dependent, although
-this portability limitation might go away in a near future by using the pthread
-cond vars. Also, the restriction against i386, i486 and Pentium might go away if
-we integrate some of glibc runtime CPU-detection tests.
+Currently, x86 (i386, i486, i586, i686), x86 64-bit, PowerPC 32/64, S390, S390x
+ARMv7l, Alpha, ia64 and Sparcv9 32/64 are supported. Only tested on Linux so
+far, but should theoretically work on other operating systems.
+
+ARMv7l depends on running a Linux kernel 2.6.15 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:
+
+- 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
+- Alpha, ia64 and ARMv7l architectures depend on 4.x gcc with atomic builtins
+ support.
+