diff --git a/common/console.c b/common/console.c
index 8c67ed33..05aa898b 100644
--- a/common/console.c
+++ b/common/console.c
@@ -105,7 +105,19 @@ void fb_console_write(void *fb_memory, const char *buf, size_t len) {
     fb_write(fb_memory, buf, len, FB_WHITE);
 }
 
+static inline bool is_console_callback_registered(console_callback_t cb, void *arg) {
+    for (unsigned int i = 0; i < num_console_callbacks; i++) {
+        if (console_callbacks[i].cb == cb && console_callbacks[i].arg == arg)
+            return true;
+    }
+
+    return false;
+}
+
 void register_console_callback(console_callback_t cb, void *arg) {
+    if (is_console_callback_registered(cb, arg))
+        return;
+
     console_callbacks[num_console_callbacks].cb = cb;
     console_callbacks[num_console_callbacks++].arg = arg;
 }
diff --git a/common/setup.c b/common/setup.c
index 97645fea..cdf4afe9 100644
--- a/common/setup.c
+++ b/common/setup.c
@@ -68,27 +68,45 @@ unsigned long cpu_frequency;
 
 #define QEMU_CONSOLE_PORT 0x0e9
 
-static void __text_init init_console(void) {
-    uart_config_t cfg = {0};
-
-    if (!parse_com_port(COM1, &cfg)) {
-        /* Use first COM port indicated by BIOS (if none, use COM1) */
-        cfg.port = get_first_com_port();
-        cfg.baud = DEFAULT_BAUD_SPEED;
-        cfg.frame_size = COM_FRAME_SIZE_8_BITS;
-        cfg.parity = COM_NO_PARITY;
-        cfg.stop_bit = COM_STOP_BIT_1;
-    }
-    init_uart(&cfg);
-    register_console_callback(serial_console_write, _ptr(cfg.port));
+static inline int __text_init init_uart_console(com_idx_t com, const uart_config_t *cfg) {
+    int rc = init_uart(com, cfg);
+
+    if (rc != 0)
+        return rc;
+
+    register_console_callback(serial_console_write, _ptr(cfg->port));
+    printk("Serial console at: ");
+    display_uart_config(com, cfg);
+
+    return rc;
+}
+
+static void __text_init init_early_console(void) {
+    uart_config_t cfg;
+
+    /* Use first COM port indicated by BIOS (if none, use COM1) */
+    cfg.port = get_first_com_port();
+    cfg.baud = DEFAULT_BAUD_SPEED;
+    cfg.frame_size = COM_FRAME_SIZE_8_BITS;
+    cfg.parity = COM_NO_PARITY;
+    cfg.stop_bit = COM_STOP_BIT_1;
+
+    init_uart_console(COM1, &cfg);
 
     if (opt_qemu_console) {
         register_console_callback(qemu_console_write, _ptr(QEMU_CONSOLE_PORT));
         printk("Initialized QEMU console at port 0x%x", QEMU_CONSOLE_PORT);
     }
+}
 
-    printk("Serial console at: ");
-    display_uart_config(&cfg);
+static void __text_init init_serial_consoles(void) {
+    uart_config_t cfg;
+
+    for (com_idx_t com = COM1; com < MAX_COM; com++) {
+        memset(&cfg, 0, sizeof(cfg));
+        if (parse_com_port(com, &cfg))
+            init_uart_console(com, &cfg);
+    }
 }
 
 static __always_inline void zero_bss(void) {
@@ -166,7 +184,7 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic, unsigned long
     zero_bss();
 
     /* Initialize console early */
-    init_console();
+    init_early_console();
 
     if (multiboot_magic == MULTIBOOT2_BOOTLOADER_MAGIC) {
         /* Indentity mapping is still on, so fill in multiboot structures */
@@ -178,6 +196,8 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic, unsigned long
     if (!string_empty(kernel_cmdline))
         printk("Command line: %s\n", kernel_cmdline);
 
+    init_serial_consoles();
+
     init_boot_traps();
 
     init_real_mode();
diff --git a/drivers/serial.c b/drivers/serial.c
index 31cf0f28..2e87077a 100644
--- a/drivers/serial.c
+++ b/drivers/serial.c
@@ -23,6 +23,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include <apic.h>
+#include <errno.h>
 #include <ioapic.h>
 #include <ktf.h>
 #include <lib.h>
@@ -39,15 +40,15 @@ static struct {
 
 io_port_t __data_rmode com_ports[4];
 
-static inline const char *com_port_name(com_port_t port) {
-    switch (port) {
-    case COM1_PORT:
+static inline const char *com_name(com_idx_t com) {
+    switch (com) {
+    case COM1:
         return "COM1";
-    case COM2_PORT:
+    case COM2:
         return "COM2";
-    case COM3_PORT:
+    case COM3:
         return "COM3";
-    case COM4_PORT:
+    case COM4:
         return "COM4";
     default:
         BUG();
@@ -68,8 +69,8 @@ static const char com_parity_names[] = {
 
 #define COM_STOP_BIT_VALUE(cfg) ((cfg)->stop_bit + 1)
 
-void display_uart_config(const uart_config_t *cfg) {
-    printk("[%s] 0x%x %u,%u%c%u\n", com_port_name(cfg->port), cfg->port, cfg->baud,
+void display_uart_config(com_idx_t com, const uart_config_t *cfg) {
+    printk("[%s] 0x%x %u,%u%c%u\n", com_name(com), cfg->port, cfg->baud,
            com_frame_size_values[cfg->frame_size], com_parity_names[cfg->parity],
            COM_STOP_BIT_VALUE(cfg));
 }
@@ -94,7 +95,7 @@ static inline void set_dlab(io_port_t port, bool dlab) {
     outb(port + UART_LCR_REG_OFFSET, lcr.reg);
 }
 
-static inline void set_port_mode(uart_config_t *cfg) {
+static inline void set_port_mode(const uart_config_t *cfg) {
     lcr_t lcr = {0};
 
     /* Set baud speed by applying divisor to DLL+DLH */
@@ -124,7 +125,20 @@ static inline bool receiver_ready(io_port_t port) {
     return msr.dsr && msr.cts;
 }
 
-void __text_init init_uart(uart_config_t *cfg) {
+#define PORT_TIMEOUT 100 /* ~100ms */
+static inline int uart_port_ready(io_port_t port) {
+    unsigned retries = PORT_TIMEOUT;
+
+    do {
+        if (receiver_ready(port))
+            return 0;
+        io_delay();
+    } while (retries--);
+
+    return -ENODEV;
+}
+
+int __text_init init_uart(com_idx_t com, const uart_config_t *cfg) {
     mcr_t mcr = {0};
     fcr_t fcr = {0};
     ier_t ier = {0};
@@ -151,8 +165,9 @@ void __text_init init_uart(uart_config_t *cfg) {
     mcr.aux = 2;
     outb(cfg->port + UART_MCR_REG_OFFSET, mcr.reg);
 
-    if (com_ports[0] == NO_COM_PORT)
-        com_ports[0] = cfg->port;
+    com_ports[com] = cfg->port;
+
+    return uart_port_ready(cfg->port);
 }
 
 void __text_init init_uart_input(const cpu_t *cpu) {
@@ -168,11 +183,11 @@ void __text_init init_uart_input(const cpu_t *cpu) {
 
 static inline int uart_port_status(io_port_t port) {
     if (!receiver_ready(port))
-        return -1; /* ENODEV */
+        return -ENODEV;
 
     if (!thr_empty(port)) {
         io_delay();
-        return 1; /* EAGAIN */
+        return -EAGAIN;
     }
 
     return 0;
@@ -203,8 +218,7 @@ int serial_putchar(io_port_t port, char c) {
 
     do {
         rc = uart_putc(port, c);
-        BUG_ON(rc < 0);
-    } while (rc > 0 && retries--);
+    } while (rc == -EAGAIN && retries--);
 
     return rc;
 }
@@ -215,8 +229,7 @@ int serial_write(io_port_t port, const char *buf, size_t len) {
 
     do {
         rc = uart_puts(port, buf, len);
-        BUG_ON(rc < 0);
-    } while (rc > 0 && retries--);
+    } while (rc == -EAGAIN && retries--);
 
     return rc;
 }
diff --git a/include/drivers/serial.h b/include/drivers/serial.h
index f631e07d..326ea8fa 100644
--- a/include/drivers/serial.h
+++ b/include/drivers/serial.h
@@ -34,6 +34,7 @@ enum com_idx {
     COM2 = 1,
     COM3 = 2,
     COM4 = 3,
+    MAX_COM,
 };
 typedef enum com_idx com_idx_t;
 
@@ -199,12 +200,12 @@ typedef enum com_irq com_irq_t;
 extern io_port_t com_ports[4];
 
 extern io_port_t get_first_com_port(void);
-extern void init_uart(uart_config_t *cfg);
+extern int init_uart(com_idx_t com, const uart_config_t *cfg);
 extern void init_uart_input(const cpu_t *cpu);
 extern void uart_interrupt_handler(void);
 extern int serial_putchar(io_port_t port, char c);
 extern int serial_write(io_port_t port, const char *buf, size_t len);
 
-extern void display_uart_config(const uart_config_t *cfg);
+extern void display_uart_config(com_idx_t com, const uart_config_t *cfg);
 
 #endif /* KTF_DRV_SERIAL_H */