Document potential build issues on RPM

README.rst

@@ -126,6 +126,56 @@ path either.  The following recipe should work::
 
   sudo PATH="/usr/pgsql-9.0/bin:$PATH" make USE_PGXS=1 install
 
+Issues with 32 and 64 bit RPMs
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If when building, you receive a series of errors of this form::
+
+  /usr/bin/ld: skipping incompatible /usr/pgsql-9.0/lib/libpq.so when searching for -lpq
+
+This is likely because you have both the 32 and 64 bit versions of the
+``postgresql90-devel`` package installed.  You can check that like this::
+
+  rpm -qa --queryformat '%{NAME}\t%{ARCH}\n'  | grep postgresql90-devel
+
+And if two packages appear, one for i386 and one for x86_64, that's not supposed
+to be allowed.
+
+This can happen when using the PGDG repo to install that package;
+here is an example sessions demonstrating the problem case appearing::
+
+  # yum install postgresql-devel
+  ..
+  Setting up Install Process
+  Resolving Dependencies
+  --> Running transaction check
+  ---> Package postgresql90-devel.i386 0:9.0.2-2PGDG.rhel5 set to be updated
+  ---> Package postgresql90-devel.x86_64 0:9.0.2-2PGDG.rhel5 set to be updated
+  --> Finished Dependency Resolution
+  
+  Dependencies Resolved
+
+  =========================================================================
+   Package               Arch      Version              Repository    Size
+  =========================================================================
+  Installing:
+   postgresql90-devel    i386      9.0.2-2PGDG.rhel5    pgdg90        1.5 M
+   postgresql90-devel    x86_64    9.0.2-2PGDG.rhel5    pgdg90        1.6 M
+
+Note how both the i386 and x86_64 platform architectures are selected for
+installation.  Your main PostgreSQL package will only be compatible with one of
+those, and if the repmgr build finds the wrong postgresql90-devel these
+"skipping incompatible" messages appear.
+
+In this case, you can temporarily remove both packages, then just install the
+correct one for your architecture.  Example::
+
+  rpm -e postgresql90-devel --allmatches
+  yum install postgresql90-devel-9.0.2-2PGDG.rhel5.x86_64
+
+Instead just deleting the package from the wrong platform might not leave behind
+the correct files, due to the way in which these accidentally happen to interact.
+
 Confirm software was built correctly
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~