build: add --enable-pmix-bootstrap support

Problem: on some platforms PMIx is the preferred mechanism
to use for bootstrapping Flux.

Prepare to add PMIx support to the Flux broker by adding
an "opt in" configure option: --enable-pmix-bootstrap.
If specified, pkg-config is used to locate a suitable pmix
package.  Configure fails if pmix is requested but not found.

Add PMIX_LIBS and PMIX_CFLAGS to the broker Makefile.am.

Co-authored-by: Jim Garlick <[email protected]>

config/x_ac_pmix.m4

@@ -0,0 +1,10 @@
+# It is fatal if --enable-pmix-bootstrap and pmix package not found.
+# (PKG_CHECK_MODULES default behavior is to fail if package not found)
+AC_DEFUN([X_AC_PMIX], [
+    AC_ARG_ENABLE([pmix-bootstrap],
+        AS_HELP_STRING([--enable-pmix-bootstrap], [Enable PMIx bootstrap]))
+    AS_IF([test "x$enable_pmix_bootstrap" = "xyes"], [
+        PKG_CHECK_MODULES([PMIX], [pmix])
+        AC_DEFINE([HAVE_LIBPMIX], [1], [Enable PMIx bootstrap])
+    ])
+])

configure.ac

@@ -385,6 +385,8 @@ AS_IF([test "x$enable_content_s3" = "xyes"], [
 
 AM_CONDITIONAL([ENABLE_CONTENT_S3], [test "x$enable_content_s3" = "xyes"])
 
+X_AC_PMIX
+
 ##
 # Check for systemd
 ##

src/broker/Makefile.am

@@ -8,6 +8,7 @@ AM_CPPFLAGS = \
 	-I$(top_srcdir) \
 	-I$(top_srcdir)/src/include \
 	-I$(top_builddir)/src/common/libflux \
+	$(PMIX_CFLAGS) \
 	$(ZMQ_CFLAGS) \
 	$(LIBUUID_CFLAGS) \
 	$(VALGRIND_CFLAGS)
@@ -64,7 +65,8 @@ flux_broker_LDADD = \
 	$(builddir)/libbroker.la \
 	$(top_builddir)/src/common/libflux-core.la \
 	$(top_builddir)/src/common/libpmi/libpmi_client.la \
-	$(top_builddir)/src/common/libflux-internal.la
+	$(top_builddir)/src/common/libflux-internal.la \
+	$(PMIX_LIBS)
 
 flux_broker_LDFLAGS =
 
@@ -82,7 +84,8 @@ test_ldadd = \
 	$(top_builddir)/src/common/libflux-core.la \
 	$(top_builddir)/src/common/libpmi/libpmi_client.la \
 	$(top_builddir)/src/common/libflux-internal.la \
-	$(top_builddir)/src/common/libtap/libtap.la
+	$(top_builddir)/src/common/libtap/libtap.la \
+	$(PMIX_LIBS)
 
 test_ldflags = \
 	-no-install