diff --git a/src/emu/bay.c b/src/emu/bay.c
index 1f5a400..3a26856 100644
--- a/src/emu/bay.c
+++ b/src/emu/bay.c
@@ -172,7 +172,7 @@ propagate_chan(struct bay_chan *bchan, enum bay_cb_type type)
 	DL_FOREACH(bchan->cb[type], cur) {
 		dbg("calling cb %p", cur->func);
 		if (cur->func(bchan->chan, cur->arg) != 0) {
-			err("callback failed");
+			err("callback failed for %s", bchan->chan->name);
 			return -1;
 		}
 	}
diff --git a/src/emu/cpu.c b/src/emu/cpu.c
index e2cab19..71c8989 100644
--- a/src/emu/cpu.c
+++ b/src/emu/cpu.c
@@ -1,6 +1,8 @@
 /* Copyright (c) 2021-2023 Barcelona Supercomputing Center (BSC)
  * SPDX-License-Identifier: GPL-3.0-or-later */
 
+//#define ENABLE_DEBUG
+
 #include "cpu.h"
 #include <stdio.h>
 #include <string.h>
@@ -248,6 +250,9 @@ cpu_update(struct cpu *cpu)
 		err("chan_set pid failed");
 		return -1;
 	}
+	char buf[128];
+	dbg("cpu%ld sets th_running to %s",
+			cpu->gindex, value_str(gid_running, buf));
 	if (chan_set(&cpu->chan[CPU_CHAN_THRUN], gid_running) != 0) {
 		err("chan_set gid_running failed");
 		return -1;
diff --git a/src/emu/thread.c b/src/emu/thread.c
index 1fdeff3..1ca5a66 100644
--- a/src/emu/thread.c
+++ b/src/emu/thread.c
@@ -1,6 +1,8 @@
 /* Copyright (c) 2021-2023 Barcelona Supercomputing Center (BSC)
  * SPDX-License-Identifier: GPL-3.0-or-later */
 
+//#define ENABLE_DEBUG
+
 #include "thread.h"
 #include <errno.h>
 #include <stdio.h>
@@ -387,6 +389,7 @@ thread_set_cpu(struct thread *th, struct cpu *cpu)
 		return -1;
 	}
 
+	dbg("thread%ld sets cpu%ld", th->gindex, cpu->gindex);
 	th->cpu = cpu;
 
 	/* Update cpu channel */
@@ -407,6 +410,7 @@ thread_unset_cpu(struct thread *th)
 		return -1;
 	}
 
+	dbg("thread%ld unsets cpu", th->gindex);
 	th->cpu = NULL;
 
 	struct chan *c = &th->chan[TH_CHAN_CPU];
@@ -426,6 +430,7 @@ thread_migrate_cpu(struct thread *th, struct cpu *cpu)
 		return -1;
 	}
 
+	dbg("thread%ld migrates to cpu%d", th->gindex, cpu->gindex);
 	th->cpu = cpu;
 
 	struct chan *c = &th->chan[TH_CHAN_CPU];