diff --git a/exosphere/src/bootup.c b/exosphere/src/bootup.c
index 962ef8e75..4836f4610 100644
--- a/exosphere/src/bootup.c
+++ b/exosphere/src/bootup.c
@@ -31,6 +31,7 @@
 #include "configitem.h"
 #include "timers.h"
 #include "misc.h"
+#include "uart.h"
 #include "bpmp.h"
 #include "sysreg.h"
 #include "interrupt.h"
@@ -213,6 +214,13 @@ void bootup_misc_mmio(void) {
     }
 
     if (!g_has_booted_up) {
+        /* N doesn't do this, but we should for compatibility. */
+        if (configitem_is_debugmode_priv()) {
+            uart_select(UART_A);
+            clkrst_reboot(CARDEVICE_UARTA);
+            uart_init(UART_A, 115200);
+        }
+        
         intr_register_handler(INTERRUPT_ID_SECURITY_ENGINE, se_operation_completed);
         if (exosphere_get_target_firmware() >= EXOSPHERE_TARGET_FIRMWARE_400) {
             intr_register_handler(INTERRUPT_ID_ACTIVITY_MONITOR_4X, actmon_interrupt_handler);
diff --git a/exosphere/src/configitem.c b/exosphere/src/configitem.c
index a0309ec2b..cac02b835 100644
--- a/exosphere/src/configitem.c
+++ b/exosphere/src/configitem.c
@@ -72,6 +72,15 @@ bool configitem_should_profile_battery(void) {
     return g_battery_profile;
 }
 
+bool configitem_is_debugmode_priv(void) {
+    uint64_t debugmode = 0;
+    if (configitem_get(true, CONFIGITEM_ISDEBUGMODE, &debugmode) != 0) {
+        generic_panic();
+    }
+
+    return debugmode != 0;
+}
+
 uint64_t configitem_get_hardware_type(void) {
     uint64_t hardware_type;
     if (configitem_get(true, CONFIGITEM_HARDWARETYPE, &hardware_type) != 0) {
diff --git a/exosphere/src/configitem.h b/exosphere/src/configitem.h
index 8aef4e975..df54c5740 100644
--- a/exosphere/src/configitem.h
+++ b/exosphere/src/configitem.h
@@ -50,6 +50,7 @@ uint32_t configitem_get(bool privileged, ConfigItem item, uint64_t *p_outvalue);
 bool configitem_is_recovery_boot(void);
 bool configitem_is_retail(void);
 bool configitem_should_profile_battery(void);
+bool configitem_is_debugmode_priv(void);
 
 void configitem_set_debugmode_override(bool user, bool priv);
 
diff --git a/exosphere/src/lp0.c b/exosphere/src/lp0.c
index e6e19d3bf..e38693cf0 100644
--- a/exosphere/src/lp0.c
+++ b/exosphere/src/lp0.c
@@ -35,6 +35,7 @@
 #include "smc_api.h"
 #include "timers.h"
 #include "misc.h"
+#include "uart.h"
 #include "exocfg.h"
 
 #define u8 uint8_t
@@ -241,7 +242,7 @@ void save_se_and_power_down_cpu(void) {
     save_se_state();
 
     if (!configitem_is_retail()) {
-        /* TODO: uart_log("OYASUMI"); */
+        uart_send(UART_A, "OYASUMI", 8);
     }
     
     finalize_powerdown();
diff --git a/exosphere/src/warmboot_main.c b/exosphere/src/warmboot_main.c
index 8ee15c4fd..d6f66aeb3 100644
--- a/exosphere/src/warmboot_main.c
+++ b/exosphere/src/warmboot_main.c
@@ -30,6 +30,7 @@
 #include "car.h"
 #include "i2c.h"
 #include "misc.h"
+#include "uart.h"
 #include "interrupt.h"
 
 #include "pmc.h"
@@ -55,8 +56,16 @@ void __attribute__((noreturn)) warmboot_main(void) {
 
     /* On warmboot (not cpu_on) only */
     if (VIRT_MC_SECURITY_CFG3 == 0) {
+        /* N only does this on dev units, but we will do it unconditionally. */
+        {
+            uart_select(UART_A);
+            clkrst_reboot(CARDEVICE_UARTA);
+            uart_init(UART_A, 115200);
+        }
+        
         if (!configitem_is_retail()) {
-            /* TODO: uart_log("OHAYO"); */
+            uart_send(UART_A, "OHAYO", 6);
+            uart_wait_idle(UART_A, UART_VENDOR_STATE_TX_IDLE);
         }
 
         /* Sanity check the Security Engine. */