Build system: use SPDX identifiers

[userspace-rcu.git] / README.md

diff --git a/README.md b/README.md
index 38a76c29740a8286eabc92edb29b5eadc520b0a4..a9f1688f5d2e1bcbd1dd577bc83f14261bc1c45f 100644 (file)
--- a/README.md
+++ b/README.md
@@ -1,3 +1,9 @@
+<!--
+SPDX-FileCopyrightText: 2023 EfficiOS Inc.
+
+SPDX-License-Identifier: CC-BY-4.0
+-->
+
 Userspace RCU Implementation
 ============================
 
@@ -55,8 +61,7 @@ Currently, the following architectures are supported:
 Tested on:
 
   - Linux all architectures
-  - FreeBSD 8.2/8.3/9.0/9.1/10.0 i386/amd64
-  - Solaris 10/11 i386
+  - FreeBSD 13 i386/amd64
   - Cygwin i386/amd64
   - MacOS amd64/arm64
 
@@ -65,18 +70,19 @@ Should also work on:
   - Android
   - NetBSD 5
   - OpenBSD
-  - Darwin
+  - Solaris
 
 (more testing needed before claiming support for these OS).
 
-Linux ARM depends on running a Linux kernel 2.6.15 or better, GCC 4.4 or
-better.
 
-The C compiler used needs to support at least C99. The C++ compiler used
-needs to support at least C++11.
+Toolchain 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:
+The C compiler used needs to support at least C99. The C++ compiler used needs
+to support at least C++11. The oldest GCC version officialy supported and
+tested is 4.8.
+
+Older GCC versions might still work 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
@@ -97,6 +103,10 @@ Clang version 3.0 (based on LLVM 3.0) is supported.
 Glibc >= 2.4 should work but the older version we test against is
 currently 2.17.
 
+
+Build system
+------------
+
 For developers using the Git tree:
 
 This source tree is based on the autotools suite from GNU to simplify
@@ -176,7 +186,7 @@ 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. Use the --disable-sys-membarrier-fallback configure option
+read-side. Use the `--disable-sys-membarrier-fallback` configure option
 to disable the fall back, thus requiring `sys_membarrier()` to be
 available. This gives a small speedup when `sys_membarrier()` is
 supported by the kernel, and aborts in the library constructor if not
@@ -251,6 +261,14 @@ protected pointer.
 After, `urcu_<flavor>_synchronize_rcu()` must be called. When it
 returns, the old values are not in usage anymore.
 
+As an alternative to `urcu_<flavor>_synchronize_rcu()`,
+it is also possible to use the urcu polling mechanism to wait for a
+grace period to elapse. This can be done by using
+`urcu_<flavor>_start_poll_synchronize_rcu()`
+to start the grace period polling, and then invoke
+`urcu_<flavor>_poll_state_synchronize_rcu()`, which returns true if
+the grace period has completed, false otherwise.
+
 
 ### Usage of `liburcu-defer`
 
@@ -382,7 +400,8 @@ By default the library is configured with internal debugging
 self-checks disabled.
 
 For always-on debugging self-checks:
-       ./configure --enable-rcu-debug
+
+    ./configure --enable-rcu-debug
 
 For fine grained enabling of debugging self-checks, build
 userspace-rcu with `DEBUG_RCU` defined and compile dependent
@@ -413,7 +432,7 @@ theoretically yielding slightly better performance.
 By default the library is configured with extra debugging checks for
 lock-free hash table iterator traversal disabled.
 
-Building liburcu with --enable-cds-lfht-iter-debug and rebuilding
+Building liburcu with `--enable-cds-lfht-iter-debug` and rebuilding
 application to match the ABI change allows finding cases where the hash
 table iterator is re-purposed to be used on a different hash table while
 still being used to iterate on a hash table.
@@ -447,7 +466,7 @@ follows:
 
   - An application executable is built with `_LGPL_SOURCE` defined, includes
     any of the Userspace RCU 0.10 urcu flavor headers, and is built
-    without the -fpic compiler option.
+    without the `-fpic` compiler option.
 
   - The Userspace RCU 0.10 library shared objects are updated to 0.11
     or 0.12 without rebuilding the application.
@@ -459,7 +478,7 @@ Some possible work-arounds for this are:
 
   - Rebuild the application against Userspace RCU 0.11+.
 
-  - Rebuild the application with -fpic.
+  - Rebuild the application with `-fpic`.
 
   - Upgrade Userspace RCU to 0.13+ without installing 0.11 nor 0.12.