When netbooting, as soon as we've figured out which interface we booted

from, store its name in a kenv variable.

sys/nfsclient/bootp_subr.c

@@ -1773,6 +1773,8 @@ bootpc_init(void)
 
 	if (gctx->gotrootpath != 0) {
 
+		setenv("boot.netif.name", ifctx->ifp->if_xname);
+
 		error = md_mount(&nd->root_saddr, nd->root_hostnam,
 				 nd->root_fh, &nd->root_fhsize,
 				 &nd->root_args, td);

sys/nfsclient/nfs_diskless.c

@@ -123,6 +123,7 @@ nfs_setup_diskless(void)
 	printf("nfs_diskless: no interface\n");
 	return;	/* no matching interface */
 match_done:
+	setenv("boot.netif.name", ifp->if_xname);
 	strlcpy(nd->myif.ifra_name, ifp->if_xname, sizeof(nd->myif.ifra_name));
 	
 	/* set up gateway */