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| -rw-r--r-- | HOWTO/INSTALL.md | 25 |
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diff --git a/HOWTO/INSTALL.md b/HOWTO/INSTALL.md index 7a7e63164c..53b1b8cd8a 100644 --- a/HOWTO/INSTALL.md +++ b/HOWTO/INSTALL.md @@ -409,6 +409,30 @@ 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 on 32-bit +and 64-bit x86, 32-bit and 64-bit SPARC V9, and 32-bit PowerPC. When compiling +with a `gcc` compatible compiler on other architectures, the VM may be able to +make use of native atomic operations using the `__sync_*` primitives, but this +should only be used as a last resort since this wont give you optimal +performance. When compiling on Windows using a MicroSoft Visual C++ compiler +native atomic memory operations are provided by Windows APIs. + +You are recommended to use the native atomic implementation provided by +Erlang/OTP, or the API provided by Windows. If these do not provide native +atomics on your platform, 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 platforms 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. ### Building ### @@ -862,3 +886,4 @@ 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/ |