diff --git a/app/iscsi_tgt/iscsi_tgt.c b/app/iscsi_tgt/iscsi_tgt.c
index 1dbc606d7..b780a3771 100644
--- a/app/iscsi_tgt/iscsi_tgt.c
+++ b/app/iscsi_tgt/iscsi_tgt.c
@@ -63,7 +63,7 @@ iscsi_usage(void)
 }
 
 static void
-spdk_startup(void *arg1, void *arg2)
+spdk_startup(void *arg1)
 {
 	if (getenv("MEMZONE_DUMP") != NULL) {
 		spdk_memzone_dump(stdout);
diff --git a/app/nvmf_tgt/nvmf_main.c b/app/nvmf_tgt/nvmf_main.c
index da079d481..87e402149 100644
--- a/app/nvmf_tgt/nvmf_main.c
+++ b/app/nvmf_tgt/nvmf_main.c
@@ -48,7 +48,7 @@ nvmf_parse_arg(int ch, char *arg)
 }
 
 static void
-nvmf_tgt_started(void *arg1, void *arg2)
+nvmf_tgt_started(void *arg1)
 {
 	if (getenv("MEMZONE_DUMP") != NULL) {
 		spdk_memzone_dump(stdout);
diff --git a/app/spdk_tgt/spdk_tgt.c b/app/spdk_tgt/spdk_tgt.c
index b30e552c0..2dde2f47f 100644
--- a/app/spdk_tgt/spdk_tgt.c
+++ b/app/spdk_tgt/spdk_tgt.c
@@ -96,7 +96,7 @@ spdk_tgt_parse_arg(int ch, char *arg)
 }
 
 static void
-spdk_tgt_started(void *arg1, void *arg2)
+spdk_tgt_started(void *arg1)
 {
 	if (g_pid_path) {
 		spdk_tgt_save_pid(g_pid_path);
diff --git a/app/vhost/vhost.c b/app/vhost/vhost.c
index 5bae19be6..4457edd7d 100644
--- a/app/vhost/vhost.c
+++ b/app/vhost/vhost.c
@@ -79,7 +79,7 @@ vhost_parse_arg(int ch, char *arg)
 }
 
 static void
-vhost_started(void *arg1, void *arg2)
+vhost_started(void *arg1)
 {
 }
 
diff --git a/examples/bdev/hello_world/hello_bdev.c b/examples/bdev/hello_world/hello_bdev.c
index 29164dfa4..92e977ef2 100644
--- a/examples/bdev/hello_world/hello_bdev.c
+++ b/examples/bdev/hello_world/hello_bdev.c
@@ -188,7 +188,7 @@ hello_write(void *arg)
  * Our initial event that kicks off everything from main().
  */
 static void
-hello_start(void *arg1, void *arg2)
+hello_start(void *arg1)
 {
 	struct hello_context_t *hello_context = arg1;
 	uint32_t blk_size, buf_align;
diff --git a/examples/blob/cli/blobcli.c b/examples/blob/cli/blobcli.c
index 7b9948e41..e52b77561 100644
--- a/examples/blob/cli/blobcli.c
+++ b/examples/blob/cli/blobcli.c
@@ -49,7 +49,7 @@
  * include it here.
  */
 #include "../lib/blob/blobstore.h"
-static void cli_start(void *arg1, void *arg2);
+static void cli_start(void *arg1);
 
 static const char *program_name = "blobcli";
 /* default name for .conf file, any name can be used however with -c switch */
@@ -233,7 +233,7 @@ unload_complete(void *cb_arg, int bserrno)
 		/* when action is CLI_NONE, we know we need to remain in the shell */
 		cli_context->bs = NULL;
 		cli_context->action = CLI_NONE;
-		cli_start(cli_context, NULL);
+		cli_start(cli_context);
 	}
 }
 
@@ -912,7 +912,7 @@ list_bdevs(struct cli_context_t *cli_context)
 		spdk_app_stop(0);
 	} else {
 		cli_context->action = CLI_NONE;
-		cli_start(cli_context, NULL);
+		cli_start(cli_context);
 	}
 }
 
@@ -973,7 +973,7 @@ spdk_bsdump_done(void *arg, int bserrno)
 		spdk_app_stop(0);
 	} else {
 		cli_context->action = CLI_NONE;
-		cli_start(cli_context, NULL);
+		cli_start(cli_context);
 	}
 }
 
@@ -1424,7 +1424,7 @@ cli_shell(void *arg1, void *arg2)
  * called first.
  */
 static void
-cli_start(void *arg1, void *arg2)
+cli_start(void *arg1)
 {
 	struct cli_context_t *cli_context = arg1;
 
diff --git a/examples/blob/hello_world/hello_blob.c b/examples/blob/hello_world/hello_blob.c
index 9e607610f..02207678c 100644
--- a/examples/blob/hello_world/hello_blob.c
+++ b/examples/blob/hello_world/hello_blob.c
@@ -395,7 +395,7 @@ bs_init_complete(void *cb_arg, struct spdk_blob_store *bs,
  * Our initial event that kicks off everything from main().
  */
 static void
-hello_start(void *arg1, void *arg2)
+hello_start(void *arg1)
 {
 	struct hello_context_t *hello_context = arg1;
 	struct spdk_bdev *bdev = NULL;
diff --git a/examples/sock/hello_world/hello_sock.c b/examples/sock/hello_world/hello_sock.c
index 5c2a71e79..b3dc5e792 100644
--- a/examples/sock/hello_world/hello_sock.c
+++ b/examples/sock/hello_world/hello_sock.c
@@ -407,7 +407,7 @@ hello_start(void *arg1, int rc)
 }
 
 static void
-start_net_framework(void *arg1, void *arg2)
+start_net_framework(void *arg1)
 {
 	spdk_net_framework_start(hello_start, arg1);
 }
diff --git a/include/spdk/event.h b/include/spdk/event.h
index cc59c683f..0260cc215 100644
--- a/include/spdk/event.h
+++ b/include/spdk/event.h
@@ -46,6 +46,7 @@
 #include "spdk/cpuset.h"
 #include "spdk/queue.h"
 #include "spdk/log.h"
+#include "spdk/thread.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -140,21 +141,23 @@ void spdk_app_opts_init(struct spdk_app_opts *opts);
 /**
  * Start the framework.
  *
- * Before calling this function, the fields of opts must be initialized by
- * spdk_app_opts_init(). Once started, the framework will call start_fn on the
- * master core with the arguments provided. This call will block until spdk_app_stop()
- * is called, or if an error condition occurs during the intialization
- * code within spdk_app_start(), itself, before invoking the caller's
- * supplied function.
+ * Before calling this function, opts must be initialized by
+ * spdk_app_opts_init(). Once started, the framework will call start_fn on
+ * an spdk_thread running on the current system thread with the
+ * argument provided. This call will block until spdk_app_stop()
+ * is called. If an error condition occurs during the intialization
+ * code within spdk_app_start(), this function will immediately return
+ * before invoking start_fn.
  *
  * \param opts Initialization options used for this application.
- * \param start_fn Event function that is called when the framework starts.
- * \param arg1 Argument passed to function start_fn.
+ * \param start_fn Entry point that will execute on an internally created thread
+ *                 once the framework has been started.
+ * \param ctx Argument passed to function start_fn.
  *
  * \return 0 on success or non-zero on failure.
  */
-int spdk_app_start(struct spdk_app_opts *opts, spdk_event_fn start_fn,
-		   void *arg1);
+int spdk_app_start(struct spdk_app_opts *opts, spdk_msg_fn start_fn,
+		   void *ctx);
 
 /**
  * Perform final shutdown operations on an application using the event framework.
diff --git a/lib/event/app.c b/lib/event/app.c
index a10f266a2..0b17fb8ff 100644
--- a/lib/event/app.c
+++ b/lib/event/app.c
@@ -67,7 +67,7 @@ struct spdk_app {
 };
 
 static struct spdk_app g_spdk_app;
-static spdk_event_fn g_start_fn = NULL;
+static spdk_msg_fn g_start_fn = NULL;
 static void *g_start_arg = NULL;
 static struct spdk_event *g_shutdown_event = NULL;
 static uint32_t g_init_lcore;
@@ -352,7 +352,7 @@ spdk_app_start_application(void)
 
 	assert(spdk_env_get_current_core() == g_init_lcore);
 
-	g_start_fn(g_start_arg, NULL);
+	g_start_fn(g_start_arg);
 }
 
 static void
@@ -574,7 +574,7 @@ bootstrap_fn(void *arg1, void *arg2)
 }
 
 int
-spdk_app_start(struct spdk_app_opts *opts, spdk_event_fn start_fn,
+spdk_app_start(struct spdk_app_opts *opts, spdk_msg_fn start_fn,
 	       void *arg1)
 {
 	struct spdk_conf	*config = NULL;
diff --git a/lib/rocksdb/env_spdk.cc b/lib/rocksdb/env_spdk.cc
index 91d9da5ab..748e6df61 100644
--- a/lib/rocksdb/env_spdk.cc
+++ b/lib/rocksdb/env_spdk.cc
@@ -623,8 +623,7 @@ fs_load_cb(__attribute__((unused)) void *ctx,
 }
 
 static void
-spdk_rocksdb_run(__attribute__((unused)) void *arg1,
-		 __attribute__((unused)) void *arg2)
+spdk_rocksdb_run(__attribute__((unused)) void *arg1)
 {
 	struct spdk_bdev *bdev;
 
diff --git a/test/app/bdev_svc/bdev_svc.c b/test/app/bdev_svc/bdev_svc.c
index 946fa1d82..84580d3f6 100644
--- a/test/app/bdev_svc/bdev_svc.c
+++ b/test/app/bdev_svc/bdev_svc.c
@@ -51,7 +51,7 @@ bdev_svc_parse_arg(int ch, char *arg)
 }
 
 static void
-bdev_svc_start(void *arg1, void *arg2)
+bdev_svc_start(void *arg1)
 {
 	int fd;
 	int shm_id = (intptr_t)arg1;
diff --git a/test/app/stub/stub.c b/test/app/stub/stub.c
index 5defa73c4..2b525f40d 100644
--- a/test/app/stub/stub.c
+++ b/test/app/stub/stub.c
@@ -80,7 +80,7 @@ stub_sleep(void *arg)
 }
 
 static void
-stub_start(void *arg1, void *arg2)
+stub_start(void *arg1)
 {
 	int shm_id = (intptr_t)arg1;
 
diff --git a/test/bdev/bdevio/bdevio.c b/test/bdev/bdevio/bdevio.c
index ffef2c3b8..9e7b7ed47 100644
--- a/test/bdev/bdevio/bdevio.c
+++ b/test/bdev/bdevio/bdevio.c
@@ -912,7 +912,7 @@ __run_ut_thread(void *arg1, void *arg2)
 }
 
 static void
-test_main(void *arg1, void *arg2)
+test_main(void *arg1)
 {
 	struct spdk_event *event;
 
diff --git a/test/bdev/bdevperf/bdevperf.c b/test/bdev/bdevperf/bdevperf.c
index 88d6b1443..64e90ae43 100644
--- a/test/bdev/bdevperf/bdevperf.c
+++ b/test/bdev/bdevperf/bdevperf.c
@@ -862,7 +862,7 @@ ret:
 }
 
 static void
-bdevperf_run(void *arg1, void *arg2)
+bdevperf_run(void *arg1)
 {
 	uint32_t i;
 	struct io_target *target;
diff --git a/test/blobfs/fuse/fuse.c b/test/blobfs/fuse/fuse.c
index 13b956eaa..7e1ff6d24 100644
--- a/test/blobfs/fuse/fuse.c
+++ b/test/blobfs/fuse/fuse.c
@@ -298,7 +298,7 @@ init_cb(void *ctx, struct spdk_filesystem *fs, int fserrno)
 }
 
 static void
-spdk_fuse_run(void *arg1, void *arg2)
+spdk_fuse_run(void *arg1)
 {
 	construct_targets();
 	spdk_fs_load(g_bs_dev, __send_request, init_cb, NULL);
diff --git a/test/blobfs/mkfs/mkfs.c b/test/blobfs/mkfs/mkfs.c
index 8d1ee7166..7a186766a 100644
--- a/test/blobfs/mkfs/mkfs.c
+++ b/test/blobfs/mkfs/mkfs.c
@@ -69,7 +69,7 @@ init_cb(void *ctx, struct spdk_filesystem *fs, int fserrno)
 }
 
 static void
-spdk_mkfs_run(void *arg1, void *arg2)
+spdk_mkfs_run(void *arg1)
 {
 	struct spdk_bdev *bdev;
 	struct spdk_blobfs_opts blobfs_opt;
diff --git a/test/event/event_perf/event_perf.c b/test/event/event_perf/event_perf.c
index a2f61f733..fe44e604d 100644
--- a/test/event/event_perf/event_perf.c
+++ b/test/event/event_perf/event_perf.c
@@ -85,7 +85,7 @@ event_work_fn(void *arg1, void *arg2)
 }
 
 static void
-event_perf_start(void *arg1, void *arg2)
+event_perf_start(void *arg1)
 {
 	uint32_t i;
 
diff --git a/test/event/reactor/reactor.c b/test/event/reactor/reactor.c
index 97db5ef41..260ba5a02 100644
--- a/test/event/reactor/reactor.c
+++ b/test/event/reactor/reactor.c
@@ -85,7 +85,7 @@ nop(void *arg)
 }
 
 static void
-test_start(void *arg1, void *arg2)
+test_start(void *arg1)
 {
 	printf("test_start\n");
 
diff --git a/test/event/reactor_perf/reactor_perf.c b/test/event/reactor_perf/reactor_perf.c
index 0a4e1a7e5..e4287f3ed 100644
--- a/test/event/reactor_perf/reactor_perf.c
+++ b/test/event/reactor_perf/reactor_perf.c
@@ -64,7 +64,7 @@ __submit_next(void *arg1, void *arg2)
 }
 
 static void
-test_start(void *arg1, void *arg2)
+test_start(void *arg1)
 {
 	int i;