topo: permit unused links

Author: riptl

src/disco/topo/fd_topo.h

@@ -73,6 +73,8 @@ typedef struct {
     fd_frag_meta_t * mcache; /* The mcache of this link. */
     void *           dcache; /* The dcache of this link, if it has one. */
   };
+
+  uint permit_unused : 1;  /* Permit a topology where this link has no consumers */
 } fd_topo_link_t;
 
 /* A tile is a unique process that is spawned by Firedancer to represent
@@ -883,12 +885,6 @@ fd_topo_huge_page_cnt( fd_topo_t const * topo,
                        ulong             numa_idx,
                        int               include_anonymous );
 
-/* Check all invariants of the given topology to make sure it is valid.
-   An invalid topology will cause the program to abort with an error
-   message. */
-void
-fd_topo_validate( fd_topo_t const * topo );
-
 /* Prints a message describing the topology to an output stream.  If
    stdout is true, will be written to stdout, otherwise will be written
    as a NOTICE log message to the log file. */

src/disco/topo/fd_topob.c

@@ -323,8 +323,9 @@ validate( fd_topo_t const * topo ) {
   /* Each link has at least one consumer */
   for( ulong i=0UL; i<topo->link_cnt; i++ ) {
     ulong cnt = fd_topo_link_consumer_cnt( topo, &topo->links[ i ] );
-    if( FD_UNLIKELY( cnt < 1 ) )
+    if( FD_UNLIKELY( cnt < 1 && !topo->links[ i ].permit_unused ) ) {
       FD_LOG_ERR(( "link %lu (%s:%lu) has 0 consumers", i, topo->links[ i ].name, topo->links[ i ].kind_id ));
+    }
   }
 }