# 5.7.2. Installation options

The following are general installation command line options that can be used with `configure`:

- `--prefix=DIR`: Install PMIx into the base directory named `DIR`. Hence, PMIx will place its executables in `DIR/bin`, its header files in `DIR/include`, its libraries in `DIR/lib`, etc.

  Note

  Also see the section on installation location for more information on the installation prefix.

- `--disable-shared`: By default, PMIx builds a shared library, and all components are included as part of those shared library. This switch disables this default; it is really only useful when used with `--enable-static`. Specifically, this option does not imply `--enable-static`; enabling static libraries and disabling shared libraries are two independent options.

  Tip

  See this section for advice to packagers about this CLI option.

- `--enable-static`: Build PMIx as a static library, and statically link in all components. Note that this option does not imply `--disable-shared`; enabling static libraries and disabling shared libraries are two independent options.

  Tip

  See this section for advice to packagers about this CLI option.

- `--disable-wrapper-runpath` / `--disable-wrapper-rpath`: By default, the wrapper compiler (`pmixcc`) will explicitly add “runpath” and “rpath” linker flags when linking user executables on systems that support them. That is, the created executables will include a filesystem path reference to the location of PMIx’s libraries in the application executable itself. This means that the user does not have to set `LD_LIBRARY_PATH` to find PMIx’s libraries, which can be helpful if they are installed in a location that the run-time linker does not search by default.

  Using the `--disable-wrapper-r*path` options will prevent the wrappers from explicitly adding one or both of these linker flags.

  Note

  By default, the wrapper compiler prefers “runpath” behavior over “rpath” behavior.

  - Using `--disable-wrapper-runpath` alters this preference: explicit “runpath” linker flags will not be added by the wrapper. However, “rpath” flags may still be added, if the platform supports them.

  - Using both `--disable-wrapper-runpath` and `--disable-wrapper-rpath` will prevent the wrapper from explicitly adding “runpath” and “rpath” linker flags.

  Caution

  Even if the wrapper compiler does not explicitly add “runpath” or “rpath” linker flags, the local compiler, linker, and/or operating system may implicitly enable either “runpath” or “rpath” behavior when linking.

  Important

  The `--disable-wrapper-runpath` and `--disable-wrapper-rpath` CLI options only affect the flags that the wrapper compiler uses when building PMIx-based applications. These options do not affect how PMIx is built (to include the wrapper compiler itself).

  See the Linker “rpath” and “runpath” functionality section for details on how “rpath” and “runpath” affect the building and linking of PMIx itself.

  When either of “runpath” or “rpath” behaviors are enabled, the applications will have the filesystem path location of the PMIx library hard-coded into a PMIx-based application. The most notable differences between “runpath” and “rpath” behavior are:

  - runpath

    > 1. The run-time linker first searches the paths in the `LD_LIBRARY_PATH` environment variable for the relevant PMIx library.

    > 2. If not found there, the run-time linker falls back to checking the hard-coded location for the relevant PMIx library.

  - rpath

    > 1. The run-time linker first checks the hard-coded location for the relevant PMIx library.

    > 2. If not found there, the run-time linker falls back to searching the paths in the `LD_LIBRARY_PATH` environment variable for the relevant PMIx library.

  Warning

  There are other, subtle differences between “runpath” and “rpath” which are out of scope for this documentation. You may wish to consult other sources for more information.

  For example, a decent set of explanations can be found in the slides for a Linux course entitled “Building and Using Shared Libraries on Linux // Shared Libraries: The Dynamic Linker”.

  For example, consider that you install PMIx vA.B.0 and compile/link your PMIx-based application against it. Later, you install PMIx vA.B.1 to a different installation prefix (e.g., `/opt/pmix/A.B.1` vs. `/opt/pmix/A.B.0`), and you leave the old installation intact.

  In the runpath case, you can set the `LD_LIBRARY_PATH` environment variable to point to the A.B.1 installation, and then your application will use those libraries, since the runtime will search the paths in `LD_LIBRARY_PATH` first.

  In the rpath case, since the run-time linker searches the `/opt/pmix/A.B.0` location that is hard-coded in your application first, your application will use the libraries from your A.B.0 installation (regardless of the value of the `LD_LIBRARY_PATH` environment variable).

  Note that in both cases, however, if you remove the original A.B.0 installation and set `LD_LIBRARY_PATH` to point to the A.B.1 installation, your application will use the A.B.1 libraries.

  As noted above, both runpath/rpath behaviors can be disabled via `--disable-wrapper-rpath`.

  Note

  You can also customize the compiler/linker flags that are used by the wrapper compilers to build PMIx-based applications.

- `--enable-dlopen`: Enable PMIx to load components as standalone Dynamic Shared Objects (DSOs) at run-time. This option is enabled by default.

  The opposite of this option, `--disable-dlopen`, causes the following:

  1. PMIx will not attempt to open any DSOs at run-time.

  2. configure behaves as if the `--enable-mca-static` argument was set.

  3. configure will ignore the `--enable-mca-dso` argument.

  See the description of `--enable-mca-static` / `--enable-mca-dso` for more information.

  Note

  This option does not change how PMIx’s libraries (`libpmix`, for example) will be built. You can change whether PMIx builds static or dynamic libraries via the `--enable|disable-static` and `--enable|disable-shared` arguments.

- `--enable-mca-dso[=LIST]` and `--enable-mca-static[=LIST]` These two options, along with `--enable-mca-no-build`, govern the behavior of how PMIx’s frameworks and components are built.

  The `--enable-mca-dso` option specifies which frameworks and/or components are built as Dynamic Shared Objects (DSOs). Specifically, DSOs are built as “plugins” outside of the core PMIx library, and are loaded by PMIx at run time.

  The `--enable-mca-static` option specifies which frameworks and/or components are built as part of the core PMIx library (i.e., they are not built as DSOs, and therefore do not need to be separately discovered and opened at run time).

  Both options can be used one of two ways:

  1. `--enable-mca-OPTION` (with no value)

  2. `--enable-mca-OPTION=LIST`

  `--enable-mca-OPTION=no` or `--disable-mca-OPTION` are both legal options, but have no impact on the selection logic described below. Only affirmative options change the selection process.

  `LIST` is a comma-delimited list of PMIx frameworks and/or framework+component tuples. Examples:

  - `ptl` specifies the entire PTL framework

  - `ptl-client` specifies just the CLIENT component in the PTL framework

  - `plog,ptl-client` specifies the entire PLOG framework and the CLIENT

      component in the PTL framework

  PMIx’s `configure` script uses the values of these two options when evaluating each component to determine how it should be built by evaluating these conditions in order:

  1. If an individual component’s build behavior has been specified via these two options, `configure` uses that behavior.

  2. Otherwise, if the component is in a framework whose build behavior has been specified via these two options, `configure` uses that behavior.

  3. Otherwise, `configure` uses the global default build behavior.

  At each level of the selection process, if the component is specified to be built as both a static and dso component, the static option will win.

  Note

  As of PMIx v4.2.3, `configure`’s global default is to build all components as static (i.e., part of the PMIx core library, not as DSOs). Prior to PMIx 4.2.3, the global default behavior was to build most components as DSOs.

  Important

  If the `--disable-dlopen` option is specified, then PMIx will not be able to search for DSOs at run time, and the value of the `--enable-mca-dso` option will be silently ignored.

  Some examples:

  1. Default to building all components as static (i.e., as part of the PMIx core libraries – no DSOs):

         shell$ ./configure

  2. Build all components as static, except the CLIENT PTL, which will be built as a DSO:

         shell$ ./configure --enable-mca-dso=ptl-client

  3. Build all components as static, except all PTL components, which will be built as DSOs:

         shell$ ./configure --enable-mca-dso=ptl

  4. Build all components as static, except all PLOG components and the CLIENT PTL component, which will be built as DSOs:

         shell$ ./configure --enable-mca-dso=plog,ptl-client

  5. Build all PTLs as static, except the CLIENT PTL, as the `<framework-component>` option is more specific than the `<framework>` option:

         shell$ ./configure --enable-mca-dso=ptl --enable-mca-static=ptl-client

  6. Build the CLIENT PTL as static, because the static option at the same level always wins:

         shell$ ./configure --enable-mca-dso=ptl-client --enable-mca-static=ptl-client

  Tip

  See this section for advice to packagers about this CLI option.

- `--enable-mca-no-build=LIST`: Comma-separated list of `<framework>-<component>` pairs that will not be built. For example, `--enable-mca-no-build=plog-syslog,psensor-file` will disable building both the `syslog` PLOG component and the `file` PSENSOR component.

  Note

  This option is typically only useful for components that would otherwise be built. For example, if you are on a machine without OmniPath support, it is not necessary to specify:

      shell$ ./configure --enable-mca-no-build=pnet-opa

  because the `configure` script will naturally see that you do not have support for OmniPath and will automatically skip the `opa` PNET component.

- `--disable-show-load-errors-by-default`: Set the default value of the `mca_base_component_show_load_errors` MCA variable: the `--enable` form of this option sets the MCA variable to true, the `--disable` form sets the MCA variable to false. The MCA `mca_base_component_show_load_errors` variable can still be overridden at run time via the usual MCA-variable-setting mechanisms; this configure option simply sets the default value.

  The `--disable` form of this option is intended for PMIx packagers who tend to enable support for many different types of networks and systems in their packages. For example, consider a packager who includes support for both the FOO and BAR networks in their PMIx package, both of which require support libraries (`libFOO.so` and `libBAR.so`). If an end user only has BAR hardware, they likely only have `libBAR.so` available on their systems – not `libFOO.so`. Disabling load errors by default will prevent the user from seeing potentially confusing warnings about the FOO components failing to load because `libFOO.so` is not available on their systems.

  Conversely, system administrators tend to build an PMIx that is targeted at their specific environment, and contains few (if any) components that are not needed. In such cases, they might want their users to be warned that the FOO network components failed to load (e.g., if `libFOO.so` was mistakenly unavailable), because PMIx may otherwise silently fail to provide support for that network.

- `--with-platform=FILE`: Load configure options for the build from `FILE`. Options on the command line that are not in `FILE` are also used. Options on the command line and in `FILE` are replaced by what is in `FILE`.

- `--with-libpmix-name=STRING`: Replace `libpmix.*` with `libSTRING.*`. This is provided as a convenience mechanism for third-party packagers of PMIx that might want to rename these libraries for their own purposes. This option is not intended for typical users of PMIx.