diff --git a/arch/x86/include/asm/bios_ebda.h b/arch/x86/include/asm/bios_ebda.h
index 2b00c77..4b7b8e7 100644
--- a/arch/x86/include/asm/bios_ebda.h
+++ b/arch/x86/include/asm/bios_ebda.h
@@ -17,7 +17,7 @@
 	return address;	/* 0 means none */
 }
 
-void reserve_ebda_region(void);
+void reserve_bios_regions(void);
 
 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
 /*
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 4dcdf74..c519c05 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -168,14 +168,14 @@
  * struct x86_legacy_features - legacy x86 features
  *
  * @rtc: this device has a CMOS real-time clock present
- * @ebda_search: it's safe to search for the EBDA signature in the hardware's
+ * @reserve_bios_regions: it's safe to search for the EBDA signature in the hardware's
  * 	low RAM
  * @devices: legacy x86 devices, refer to struct x86_legacy_devices
  * 	documentation for further details.
  */
 struct x86_legacy_features {
 	int rtc;
-	int ebda_search;
+	int reserve_bios_regions;
 	struct x86_legacy_devices devices;
 };
 
diff --git a/arch/x86/kernel/ebda.c b/arch/x86/kernel/ebda.c
index afe65df..6219eef 100644
--- a/arch/x86/kernel/ebda.c
+++ b/arch/x86/kernel/ebda.c
@@ -6,66 +6,104 @@
 #include <asm/bios_ebda.h>
 
 /*
+ * This function reserves all conventional PC system BIOS related
+ * firmware memory areas (some of which are data, some of which
+ * are code), that must not be used by the kernel as available
+ * RAM.
+ *
  * The BIOS places the EBDA/XBDA at the top of conventional
  * memory, and usually decreases the reported amount of
- * conventional memory (int 0x12) too. This also contains a
- * workaround for Dell systems that neglect to reserve EBDA.
- * The same workaround also avoids a problem with the AMD768MPX
- * chipset: reserve a page before VGA to prevent PCI prefetch
- * into it (errata #56). Usually the page is reserved anyways,
- * unless you have no PS/2 mouse plugged in.
+ * conventional memory (int 0x12) too.
  *
- * This functions is deliberately very conservative.  Losing
- * memory in the bottom megabyte is rarely a problem, as long
- * as we have enough memory to install the trampoline.  Using
- * memory that is in use by the BIOS or by some DMA device
- * the BIOS didn't shut down *is* a big problem.
+ * This means that as a first approximation on most systems we can
+ * guess the reserved BIOS area by looking at the low BIOS RAM size
+ * value and assume that everything above that value (up to 1MB) is
+ * reserved.
+ *
+ * But life in firmware country is not that simple:
+ *
+ * - This code also contains a quirk for Dell systems that neglect
+ *   to reserve the EBDA area in the 'RAM size' value ...
+ *
+ * - The same quirk also avoids a problem with the AMD768MPX
+ *   chipset: reserve a page before VGA to prevent PCI prefetch
+ *   into it (errata #56). (Usually the page is reserved anyways,
+ *   unless you have no PS/2 mouse plugged in.)
+ *
+ * - Plus paravirt systems don't have a reliable value in the
+ *   'BIOS RAM size' pointer we can rely on, so we must quirk
+ *   them too.
+ *
+ * Due to those various problems this function is deliberately
+ * very conservative and tries to err on the side of reserving
+ * too much, to not risk reserving too little.
+ *
+ * Losing a small amount of memory in the bottom megabyte is
+ * rarely a problem, as long as we have enough memory to install
+ * the SMP bootup trampoline which *must* be in this area.
+ *
+ * Using memory that is in use by the BIOS or by some DMA device
+ * the BIOS didn't shut down *is* a big problem to the kernel,
+ * obviously.
  */
 
-#define BIOS_LOWMEM_KILOBYTES	0x413
-#define LOWMEM_CAP		0x9f000U	/* Absolute maximum */
-#define INSANE_CUTOFF		0x20000U	/* Less than this = insane */
+#define BIOS_RAM_SIZE_KB_PTR	0x413
 
-void __init reserve_ebda_region(void)
+#define BIOS_START_MIN		0x20000U	/* 128K, less than this is insane */
+#define BIOS_START_MAX		0x9f000U	/* 640K, absolute maximum */
+
+void __init reserve_bios_regions(void)
 {
-	unsigned int lowmem, ebda_addr;
+	unsigned int bios_start, ebda_start;
 
 	/*
-	 * To determine the position of the EBDA and the
-	 * end of conventional memory, we need to look at
-	 * the BIOS data area. In a paravirtual environment
-	 * that area is absent. We'll just have to assume
-	 * that the paravirt case can handle memory setup
-	 * correctly, without our help.
+	 * NOTE: In a paravirtual environment the BIOS reserved
+	 * area is absent. We'll just have to assume that the
+	 * paravirt case can handle memory setup correctly,
+	 * without our help.
 	 */
-	if (!x86_platform.legacy.ebda_search)
+	if (!x86_platform.legacy.reserve_bios_regions)
 		return;
 
-	/* end of low (conventional) memory */
-	lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
-	lowmem <<= 10;
-
-	/* start of EBDA area */
-	ebda_addr = get_bios_ebda();
+	/* Get the start address of the EBDA page: */
+	ebda_start = get_bios_ebda();
 
 	/*
-	 * Note: some old Dells seem to need 4k EBDA without
-	 * reporting so, so just consider the memory above 0x9f000
-	 * to be off limits (bugzilla 2990).
+	 * Quirk: some old Dells seem to have a 4k EBDA without
+	 * reporting so in their BIOS RAM size value, so just
+	 * consider the memory above 640K to be off limits
+	 * (bugzilla 2990).
+	 *
+	 * We detect this case by filtering for nonsensical EBDA
+	 * addresses below 128K, where we can assume that they
+	 * are bogus and bump it up to a fixed 640K value:
 	 */
+	if (ebda_start < BIOS_START_MIN)
+		ebda_start = BIOS_START_MAX;
 
-	/* If the EBDA address is below 128K, assume it is bogus */
-	if (ebda_addr < INSANE_CUTOFF)
-		ebda_addr = LOWMEM_CAP;
+	/*
+	 * BIOS RAM size is encoded in kilobytes, convert it
+	 * to bytes to get a first guess at where the BIOS
+	 * firmware area starts:
+	 */
+	bios_start = *(unsigned short *)__va(BIOS_RAM_SIZE_KB_PTR);
+	bios_start <<= 10;
 
-	/* If lowmem is less than 128K, assume it is bogus */
-	if (lowmem < INSANE_CUTOFF)
-		lowmem = LOWMEM_CAP;
+	/*
+	 * If bios_start is less than 128K, assume it is bogus
+	 * and bump it up to 640K:
+	 */
+	if (bios_start < BIOS_START_MIN)
+		bios_start = BIOS_START_MAX;
 
-	/* Use the lower of the lowmem and EBDA markers as the cutoff */
-	lowmem = min(lowmem, ebda_addr);
-	lowmem = min(lowmem, LOWMEM_CAP); /* Absolute cap */
+	/*
+	 * Use the lower of the bios_start and ebda_start
+	 * as the starting point, but don't allow it to
+	 * go beyond 640K:
+	 */
+	bios_start = min(bios_start, ebda_start);
+	bios_start = min(bios_start, BIOS_START_MAX);
 
-	/* reserve all memory between lowmem and the 1MB mark */
-	memblock_reserve(lowmem, 0x100000 - lowmem);
+	/* Reserve all memory between bios_start and the 1MB mark: */
+	memblock_reserve(bios_start, 0x100000 - bios_start);
 }
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index d784bb5..2dda0bc 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -26,7 +26,7 @@
 	x86_init.resources.reserve_resources = i386_reserve_resources;
 	x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
 
-	reserve_ebda_region();
+	reserve_bios_regions();
 }
 
 asmlinkage __visible void __init i386_start_kernel(void)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index b72fb0b..99d48e7 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -183,7 +183,7 @@
 		copy_bootdata(__va(real_mode_data));
 
 	x86_early_init_platform_quirks();
-	reserve_ebda_region();
+	reserve_bios_regions();
 
 	switch (boot_params.hdr.hardware_subarch) {
 	case X86_SUBARCH_INTEL_MID:
diff --git a/arch/x86/kernel/platform-quirks.c b/arch/x86/kernel/platform-quirks.c
index b2f8a33..24a5030 100644
--- a/arch/x86/kernel/platform-quirks.c
+++ b/arch/x86/kernel/platform-quirks.c
@@ -7,12 +7,12 @@
 void __init x86_early_init_platform_quirks(void)
 {
 	x86_platform.legacy.rtc = 1;
-	x86_platform.legacy.ebda_search = 0;
+	x86_platform.legacy.reserve_bios_regions = 0;
 	x86_platform.legacy.devices.pnpbios = 1;
 
 	switch (boot_params.hdr.hardware_subarch) {
 	case X86_SUBARCH_PC:
-		x86_platform.legacy.ebda_search = 1;
+		x86_platform.legacy.reserve_bios_regions = 1;
 		break;
 	case X86_SUBARCH_XEN:
 	case X86_SUBARCH_LGUEST: