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Diffstat (limited to 'HOWTO/INSTALL.md')
| -rw-r--r-- | HOWTO/INSTALL.md | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/HOWTO/INSTALL.md b/HOWTO/INSTALL.md index 5b3a09df2b..7efea77d4c 100644 --- a/HOWTO/INSTALL.md +++ b/HOWTO/INSTALL.md @@ -385,7 +385,7 @@ Some of the available `configure` options are: * `--enable-static-{nifs,drivers}` - To allow usage of nifs and drivers on OSs that do not support dynamic linking of libraries it is possible to statically link nifs and drivers with the main Erlang VM binary. This is done by passing - a comma seperated list to the archives that you want to statically link. e.g. + a comma separated list to the archives that you want to statically link. e.g. `--enable-static-nifs=/home/$USER/my_nif.a`. The path has to be absolute and the name of the archive has to be the same as the module, i.e. `my_nif` in the example above. This is also true for drivers, but then it is the driver name @@ -409,6 +409,41 @@ Some of the available `configure` options are: If you or your system has special requirements please read the `Makefile` for additional configuration information. +#### Atomic Memory Operations and the VM #### + +The VM with SMP support makes quite a heavy use of atomic memory operations. +An implementation providing native atomic memory operations is therefore very +important when building Erlang/OTP. By default the VM will refuse to build +if native atomic memory operations are not available. + +Erlang/OTP itself provides implementations of native atomic memory operations +that can be used when compiling with a `gcc` compatible compiler for 32/64-bit +x86, 32/64-bit SPARC V9, 32-bit PowerPC, or 32-bit Tile. When compiling with +a `gcc` compatible compiler for other architectures, the VM may be able to make +use of native atomic operations using the `__atomic_*` builtins (may be +available when using a `gcc` of at least version 4.7) and/or using the +`__sync_*` builtins (may be available when using a `gcc` of at least version +4.1). If only the `gcc`'s `__sync_*` builtins are available, the performance +will suffer. Such a configuration should only be used as a last resort. When +compiling on Windows using a MicroSoft Visual C++ compiler native atomic +memory operations are provided by Windows APIs. + +Native atomic implementation in the order preferred: +1. The implementation provided by Erlang/OTP. +2. The API provided by Windows. +3. The implementation based on the `gcc` `__atomic_*` builtins. +4. If none of the above are available for your architecture/compiler, you + are recommended to build and install [libatomic_ops][] before building + Erlang/OTP. The `libatomic_ops` library provides native atomic memory + operations for a variety of architectures and compilers. When building + Erlang/OTP you need to inform the build system of where the + `libatomic_ops` library is installed using the + `--with-libatomic_ops=PATH` `configure` switch. +5. As a last resort, the implementation solely based on the `gcc` + `__sync_*` builtins. This will however cause lots of expensive and + unnecessary memory barrier instructions to be issued. That is, + performance will suffer. The `configure` script will warn at the end + of its execution if it cannot find any other alternative than this. ### Building ### @@ -825,7 +860,7 @@ Copyright and License %CopyrightBegin% -Copyright Ericsson AB 1998-2014. All Rights Reserved. +Copyright Ericsson AB 1998-2015. All Rights Reserved. The contents of this file are subject to the Erlang Public License, Version 1.1, (the "License"); you may not use this file except in @@ -862,3 +897,4 @@ under the License. [Optional Utilities]: #Optional-Utilities [Building on a Mac]: #Advanced-configuration-and-build-of-ErlangOTP_Building_OS-X-Darwin [Building with wxErlang]: #Advanced-configuration-and-build-of-ErlangOTP_Building_Building-with-wxErlang + [libatomic_ops]: https://github.com/ivmai/libatomic_ops/ |