diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index 5bbed3a36a..39ad935266 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -354,6 +354,8 @@ static struct page_info * __init alloc_chunk(struct domain *d,
     return page;
 }
 
+extern void serial_debug(void);
+
 int __init dom0_construct_pv(struct domain *d,
                              const module_t *image,
                              unsigned long image_headroom,
@@ -412,6 +414,7 @@ int __init dom0_construct_pv(struct domain *d,
     /* Machine address of next candidate page-table page. */
     paddr_t mpt_alloc;
 
+    serial_debug();
     printk(XENLOG_INFO "*** Building a PV Dom%d ***\n", d->domain_id);
 
     d->max_pages = ~0U;
diff --git a/xen/drivers/char/serial.c b/xen/drivers/char/serial.c
index 324024c29a..d6a4d62a07 100644
--- a/xen/drivers/char/serial.c
+++ b/xen/drivers/char/serial.c
@@ -71,6 +71,80 @@ void serial_rx_interrupt(struct serial_port *port, struct cpu_user_regs *regs)
         (*fn)(c & 0x7f, regs);
 }
 
+#include <xen/console.h>
+#include <xen/init.h>
+#include <xen/irq.h>
+#include <xen/param.h>
+#include <xen/sched.h>
+#include <xen/timer.h>
+#include <xen/serial.h>
+#include <xen/iocap.h>
+#ifdef NS16550_PCI
+#include <xen/pci.h>
+#include <xen/pci_regs.h>
+#include <xen/pci_ids.h>
+#endif
+#include <xen/8250-uart.h>
+#include <xen/vmap.h>
+#include <asm/io.h>
+#ifdef CONFIG_HAS_DEVICE_TREE
+#include <asm/device.h>
+#endif
+#ifdef CONFIG_X86
+#include <asm/fixmap.h>
+#endif
+
+#define NS16550_PCI
+
+struct ns16550 {
+    int baud, clock_hz, data_bits, parity, stop_bits, fifo_size, irq;
+    u64 io_base;   /* I/O port or memory-mapped I/O address. */
+    u64 io_size;
+    int reg_shift; /* Bits to shift register offset by */
+    int reg_width; /* Size of access to use, the registers
+                    * themselves are still bytes */
+    char __iomem *remapped_io_base;  /* Remapped virtual address of MMIO. */
+    /* UART with IRQ line: interrupt-driven I/O. */
+    struct irqaction irqaction;
+    u8 lsr_mask;
+#ifdef CONFIG_ARM
+    struct vuart_info vuart;
+#endif
+    /* UART with no IRQ line: periodically-polled I/O. */
+    struct timer timer;
+    struct timer resume_timer;
+    unsigned int timeout_ms;
+    bool intr_works;
+    bool dw_usr_bsy;
+#ifdef NS16550_PCI
+    /* PCI card parameters. */
+    bool pb_bdf_enable;     /* if =1, pb-bdf effective, port behind bridge */
+    bool ps_bdf_enable;     /* if =1, ps_bdf effective, port on pci card */
+    unsigned int pb_bdf[3]; /* pci bridge BDF */
+    unsigned int ps_bdf[3]; /* pci serial port BDF */
+    u32 bar;
+    u32 bar64;
+    u16 cr;
+    u8 bar_idx;
+    bool msi;
+    const struct ns16550_config_param *param; /* Points into .init.*! */
+#endif
+};
+
+int skipped_interrupts = 0;
+
+void serial_debug(void)
+{
+    struct serial_port *port = &com[SERHND_COM1];
+    struct ns16550 *uart = port->uart;
+    printk("SERIAL DEBUG: txbufc: %#x, txbufp: %#x, uart intr_works: %d, serial_txbufsz: %#x, tx_ready: %d, "
+            "lsr_mask: %#x, msi: %d, io_size: %ld, skipped_interrupts: %d\n",
+            port->txbufc, port->txbufp, uart->intr_works,
+            serial_txbufsz,
+            port->driver->tx_ready(port),
+            uart->lsr_mask, uart->msi, uart->io_size, skipped_interrupts);
+}
+
 void serial_tx_interrupt(struct serial_port *port, struct cpu_user_regs *regs)
 {
     int i, n;
@@ -85,8 +159,10 @@ void serial_tx_interrupt(struct serial_port *port, struct cpu_user_regs *regs)
      */
     while ( !spin_trylock(&port->tx_lock) )
     {
-        if ( port->driver->tx_ready(port) <= 0 )
+        if ( port->driver->tx_ready(port) <= 0 ) {
+            skipped_interrupts++;
             goto out;
+        }
         cpu_relax();
     }