diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index fa885174fd7588031142b80cbb1f4d41b5bf0d62..bebebe4fd469a26a6c275072eb43099cf93fe9c8 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -816,6 +816,11 @@ and is between 256 and 4096 characters. It is defined in the file
 	lasi=		[HW,SCSI] PARISC LASI driver for the 53c700 chip
 			Format: addr:<io>,irq:<irq>
 
+	legacy_serial.force [HW,IA-32,X86-64]
+			Probe for COM ports at legacy addresses even
+			if PNPBIOS or ACPI should describe them.  This
+			is for working around firmware defects.
+
 	llsc*=		[IA64] See function print_params() in
 			arch/ia64/sn/kernel/llsc4.c.
 
diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index 4f98516b9f945f208d40600dc3016b82362a8d56..91cff8dc9e1afa4018234d5aed33f122a5cd4193 100644
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -34,6 +34,7 @@ obj-y				+= sysenter.o vsyscall.o
 obj-$(CONFIG_ACPI_SRAT) 	+= srat.o
 obj-$(CONFIG_EFI) 		+= efi.o efi_stub.o
 obj-$(CONFIG_DOUBLEFAULT) 	+= doublefault.o
+obj-$(CONFIG_SERIAL_8250)	+= legacy_serial.o
 obj-$(CONFIG_VM86)		+= vm86.o
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_HPET_TIMER) 	+= hpet.o
diff --git a/arch/i386/kernel/legacy_serial.c b/arch/i386/kernel/legacy_serial.c
new file mode 100644
index 0000000000000000000000000000000000000000..21510118544e10b10b403335f644b9756d8d54f7
--- /dev/null
+++ b/arch/i386/kernel/legacy_serial.c
@@ -0,0 +1,67 @@
+/*
+ * Legacy COM port devices for x86 platforms without PNPBIOS or ACPI.
+ * Data taken from include/asm-i386/serial.h.
+ *
+ * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
+ *	Bjorn Helgaas <bjorn.helgaas@hp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/pnp.h>
+#include <linux/serial_8250.h>
+
+/* Standard COM flags (except for COM4, because of the 8514 problem) */
+#ifdef CONFIG_SERIAL_DETECT_IRQ
+#define COM_FLAGS (UPF_BOOT_AUTOCONF | UPF_SKIP_TEST | UPF_AUTO_IRQ)
+#define COM4_FLAGS (UPF_BOOT_AUTOCONF | UPF_AUTO_IRQ)
+#else
+#define COM_FLAGS (UPF_BOOT_AUTOCONF | UPF_SKIP_TEST)
+#define COM4_FLAGS UPF_BOOT_AUTOCONF
+#endif
+
+#define PORT(_base,_irq,_flags)				\
+	{						\
+		.iobase		= _base,		\
+		.irq		= _irq,			\
+		.uartclk	= 1843200,		\
+		.iotype		= UPIO_PORT,		\
+		.flags		= _flags,		\
+	}
+
+static struct plat_serial8250_port x86_com_data[] = {
+	PORT(0x3F8, 4, COM_FLAGS),
+	PORT(0x2F8, 3, COM_FLAGS),
+	PORT(0x3E8, 4, COM_FLAGS),
+	PORT(0x2E8, 3, COM4_FLAGS),
+	{ },
+};
+
+static struct platform_device x86_com_device = {
+	.name			= "serial8250",
+	.id			= PLAT8250_DEV_PLATFORM,
+	.dev			= {
+		.platform_data	= x86_com_data,
+	},
+};
+
+static int force_legacy_probe;
+module_param_named(force, force_legacy_probe, bool, 0);
+MODULE_PARM_DESC(force, "Force legacy serial port probe");
+
+static int __init serial8250_x86_com_init(void)
+{
+	if (pnp_platform_devices && !force_legacy_probe)
+		return -ENODEV;
+
+	return platform_device_register(&x86_com_device);
+}
+
+module_init(serial8250_x86_com_init);
+
+MODULE_AUTHOR("Bjorn Helgaas");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Generic 8250/16x50 legacy probe module");
diff --git a/arch/x86_64/kernel/Makefile b/arch/x86_64/kernel/Makefile
index 4d94c51803d8051e6c3db0dc790ee51957b1f62c..de1de8a2fd84669e4643585e5119fa7d2e2db594 100644
--- a/arch/x86_64/kernel/Makefile
+++ b/arch/x86_64/kernel/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_IOMMU)		+= pci-gart.o aperture.o
 obj-$(CONFIG_CALGARY_IOMMU)	+= pci-calgary.o tce.o
 obj-$(CONFIG_SWIOTLB)		+= pci-swiotlb.o
+obj-$(CONFIG_SERIAL_8250)	+= legacy_serial.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_X86_PM_TIMER)	+= pmtimer.o
 obj-$(CONFIG_X86_VSMP)		+= vsmp.o
@@ -49,6 +50,7 @@ CFLAGS_vsyscall.o		:= $(PROFILING) -g0
 
 therm_throt-y                   += ../../i386/kernel/cpu/mcheck/therm_throt.o
 bootflag-y			+= ../../i386/kernel/bootflag.o
+legacy_serial-y			+= ../../i386/kernel/legacy_serial.o
 cpuid-$(subst m,y,$(CONFIG_X86_CPUID))  += ../../i386/kernel/cpuid.o
 topology-y                     += ../../i386/kernel/topology.o
 microcode-$(subst m,y,$(CONFIG_MICROCODE))  += ../../i386/kernel/microcode.o
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 924e9bd757f0fe486e71f11796567c3cbf542d6d..e8efe938c4e740a64da3bc68627cb9ad8ae2ecaf 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -73,17 +73,21 @@ config SERIAL_8250_PCI
 	depends on SERIAL_8250 && PCI
 	default SERIAL_8250
 	help
-	  This builds standard PCI serial support. You may be able to
-	  disable this feature if you only need legacy serial support.
-	  Saves about 9K.
+	  Say Y here if you have PCI serial ports.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called 8250_pci.
 
 config SERIAL_8250_PNP
 	tristate "8250/16550 PNP device support" if EMBEDDED
 	depends on SERIAL_8250 && PNP
 	default SERIAL_8250
 	help
-	  This builds standard PNP serial support. You may be able to
-	  disable this feature if you only need legacy serial support.
+	  Say Y here if you have serial ports described by PNPBIOS or ACPI.
+	  These are typically ports built into the system board.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called 8250_pnp.
 
 config SERIAL_8250_HP300
 	tristate
diff --git a/include/asm-i386/serial.h b/include/asm-i386/serial.h
index bd67480ca1094f9896aacdf5395d0b541552fb75..57a4306cdf63e33f7a5eea692be606d90bc6cfee 100644
--- a/include/asm-i386/serial.h
+++ b/include/asm-i386/serial.h
@@ -11,19 +11,3 @@
  * megabits/second; but this requires the faster clock.
  */
 #define BASE_BAUD ( 1843200 / 16 )
-
-/* Standard COM flags (except for COM4, because of the 8514 problem) */
-#ifdef CONFIG_SERIAL_DETECT_IRQ
-#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ)
-#define STD_COM4_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_AUTO_IRQ)
-#else
-#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)
-#define STD_COM4_FLAGS ASYNC_BOOT_AUTOCONF
-#endif
-
-#define SERIAL_PORT_DFNS			\
-	/* UART CLK   PORT IRQ     FLAGS        */			\
-	{ 0, BASE_BAUD, 0x3F8, 4, STD_COM_FLAGS },	/* ttyS0 */	\
-	{ 0, BASE_BAUD, 0x2F8, 3, STD_COM_FLAGS },	/* ttyS1 */	\
-	{ 0, BASE_BAUD, 0x3E8, 4, STD_COM_FLAGS },	/* ttyS2 */	\
-	{ 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS },	/* ttyS3 */
diff --git a/include/asm-x86_64/serial.h b/include/asm-x86_64/serial.h
index b0496e0d72a68669cf5a5c1204af07bc1bcee334..8ebd765c674a2564cc5dde497a3e60e482ff3427 100644
--- a/include/asm-x86_64/serial.h
+++ b/include/asm-x86_64/serial.h
@@ -11,19 +11,3 @@
  * megabits/second; but this requires the faster clock.
  */
 #define BASE_BAUD ( 1843200 / 16 )
-
-/* Standard COM flags (except for COM4, because of the 8514 problem) */
-#ifdef CONFIG_SERIAL_DETECT_IRQ
-#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ)
-#define STD_COM4_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_AUTO_IRQ)
-#else
-#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)
-#define STD_COM4_FLAGS ASYNC_BOOT_AUTOCONF
-#endif
-
-#define SERIAL_PORT_DFNS			\
-	/* UART CLK   PORT IRQ     FLAGS        */			\
-	{ 0, BASE_BAUD, 0x3F8, 4, STD_COM_FLAGS },	/* ttyS0 */	\
-	{ 0, BASE_BAUD, 0x2F8, 3, STD_COM_FLAGS },	/* ttyS1 */	\
-	{ 0, BASE_BAUD, 0x3E8, 4, STD_COM_FLAGS },	/* ttyS2 */	\
-	{ 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS },	/* ttyS3 */