+<!--
+SPDX-FileCopyrightText: 2023 EfficiOS Inc.
+
+SPDX-License-Identifier: CC-BY-4.0
+-->
+
Userspace RCU Implementation
============================
- hppa/PA-RISC
- m68k
- RISC-V
+ - LoongArch
Tested on:
- Linux all architectures
- - FreeBSD 8.2/8.3/9.0/9.1/10.0 i386/amd64
+ - FreeBSD 13 i386/amd64
- Cygwin i386/amd64
- MacOS amd64/arm64
(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 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.
-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:
+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
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
- `memb`,
- `qsbr`,
- `mb`,
- - `signal`,
- `bp`.
The API members start with the prefix `urcu_<flavor>_`, where
results in slower reads.
-### Usage of `liburcu-signal`
-
- 1. `#include <urcu/urcu-signal.h>`
- 2. 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`
1. `#include <urcu/urcu-bp.h>`
### Usage of `liburcu-defer`
- Follow instructions for either `liburcu-memb`, `liburcu-qsbr`,
- `liburcu-mb`, `liburcu-signal`, or `liburcu-bp` above.
+ `liburcu-mb`, or `liburcu-bp` above.
The `liburcu-defer` functionality is pulled into each of
those library modules.
- Provides `urcu_<flavor>_defer_rcu()` primitive to enqueue delayed
### Usage of `urcu-call-rcu`
- Follow instructions for either `liburcu-memb`, `liburcu-qsbr`,
- `liburcu-mb`, `liburcu-signal`, or `liburcu-bp` above.
+ `liburcu-mb`, or `liburcu-bp` above.
The `urcu-call-rcu` functionality is pulled into each of
those library modules.
- Provides the `urcu_<flavor>_call_rcu()` primitive to enqueue delayed
### Being careful with signals
-The `liburcu-signal` library uses signals internally. The signal handler is
-registered with the `SA_RESTART` flag. However, these signals may cause
-some non-restartable system calls to fail with `errno = EINTR`. Care
-should be taken to restart system calls manually if they fail with this
-error. A list of non-restartable system calls may be found in
-`signal(7)`.
-
Read-side critical sections are allowed in a signal handler,
except those setup with `sigaltstack(2)`, with `liburcu-memb` and
`liburcu-mb`. Be careful, however, to disable these signals
This option alters the rculfhash ABI. Make sure to compile both library
and application with matching configuration.
+### Usage of `--enable-compiler-atomic-builtins`
+
+Building liburcu with `--enable-compiler-atomic-builtins` implements the uatomic
+API with the compiler atomic builtins if supported.
Make targets
------------