diff --git a/sys/amd64/include/minidump.h b/sys/amd64/include/minidump.h
index 1ea92b7..2ac529c 100644
--- a/sys/amd64/include/minidump.h
+++ b/sys/amd64/include/minidump.h
@@ -30,14 +30,14 @@
 #define	_MACHINE_MINIDUMP_H_ 1
 
 #define	MINIDUMP_MAGIC		"minidump FreeBSD/amd64"
-#define	MINIDUMP_VERSION	1
+#define	MINIDUMP_VERSION	2
 
 struct minidumphdr {
 	char magic[24];
 	uint32_t version;
 	uint32_t msgbufsize;
 	uint32_t bitmapsize;
-	uint32_t ptesize;
+	uint32_t pmapsize;
 	uint64_t kernbase;
 	uint64_t dmapbase;
 	uint64_t dmapend;
diff --git a/sys/amd64/amd64/minidump_machdep.c b/sys/amd64/amd64/minidump_machdep.c
index a9af809..a77bc12 100644
--- a/sys/amd64/amd64/minidump_machdep.c
+++ b/sys/amd64/amd64/minidump_machdep.c
@@ -167,63 +167,89 @@ blk_write(struct dumperinfo *di, char *ptr, vm_paddr_t pa, size_t sz)
 }
 
 /* A fake page table page, to avoid having to handle both 4K and 2M pages */
-static pt_entry_t fakept[NPTEPG];
+static pd_entry_t fakepd[NPDEPG];
 
 void
 minidumpsys(struct dumperinfo *di)
 {
 	uint64_t dumpsize;
-	uint32_t ptesize;
+	uint32_t pmapsize;
 	vm_offset_t va;
 	int error;
 	uint64_t bits;
 	uint64_t *pdp, *pd, *pt, pa;
-	int i, j, k, bit;
+	int i, j, k, n, bit;
+	int retry_count;
 	struct minidumphdr mdhdr;
 
+	retry_count = 0;
+ retry:
+	retry_count++;
 	counter = 0;
 	/* Walk page table pages, set bits in vm_page_dump */
-	ptesize = 0;
+	pmapsize = 0;
 	pdp = (uint64_t *)PHYS_TO_DMAP(KPDPphys);
 	for (va = VM_MIN_KERNEL_ADDRESS; va < MAX(KERNBASE + NKPT * NBPDR,
-	    kernel_vm_end); va += NBPDR) {
+	    kernel_vm_end); ) {
 		i = (va >> PDPSHIFT) & ((1ul << NPDPEPGSHIFT) - 1);
+
 		/*
 		 * We always write a page, even if it is zero. Each
-		 * page written corresponds to 2MB of space
+		 * page written corresponds to 1GB of space
 		 */
-		ptesize += PAGE_SIZE;
-		if ((pdp[i] & PG_V) == 0)
+		pmapsize += PAGE_SIZE;
+		if ((pdp[i] & PG_V) == 0) {
+			va += NBPDP;
 			continue;
-		pd = (uint64_t *)PHYS_TO_DMAP(pdp[i] & PG_FRAME);
-		j = ((va >> PDRSHIFT) & ((1ul << NPDEPGSHIFT) - 1));
-		if ((pd[j] & (PG_PS | PG_V)) == (PG_PS | PG_V))  {
-			/* This is an entire 2M page. */
-			pa = pd[j] & PG_PS_FRAME;
-			for (k = 0; k < NPTEPG; k++) {
+		}
+
+		/*
+		 * 1GB page is represented as 512 2MB pages in a dump.
+		 */
+		if ((pdp[i] & PG_PS) != 0) {
+			va += NBPDP;
+			pa = pdp[i] & PG_PS_FRAME;
+			for (n = 0; n < NPDEPG * NPTEPG; n++) {
 				if (is_dumpable(pa))
 					dump_add_page(pa);
 				pa += PAGE_SIZE;
 			}
 			continue;
 		}
-		if ((pd[j] & PG_V) == PG_V) {
-			/* set bit for each valid page in this 2MB block */
-			pt = (uint64_t *)PHYS_TO_DMAP(pd[j] & PG_FRAME);
-			for (k = 0; k < NPTEPG; k++) {
-				if ((pt[k] & PG_V) == PG_V) {
-					pa = pt[k] & PG_FRAME;
+
+		pd = (uint64_t *)PHYS_TO_DMAP(pdp[i] & PG_FRAME);
+		for (n = 0; n < NPDEPG; n++, va += NBPDR) {
+			j = ((va >> PDRSHIFT) & ((1ul << NPDEPGSHIFT) - 1));
+			if ((pd[j] & (PG_PS | PG_V)) == (PG_PS | PG_V))  {
+				/* This is an entire 2M page. */
+				pa = pd[j] & PG_PS_FRAME;
+				for (k = 0; k < NPTEPG; k++) {
 					if (is_dumpable(pa))
 						dump_add_page(pa);
+					pa += PAGE_SIZE;
+				}
+				continue;
+			}
+			if ((pd[j] & PG_V) == PG_V) {
+				pa = pd[j] & PG_FRAME;
+				/* set bit for this PTE page */
+				if (is_dumpable(pa))
+					dump_add_page(pa);
+				/* and for each valid page in this 2MB block */
+				pt = (uint64_t *)PHYS_TO_DMAP(pd[j] & PG_FRAME);
+				for (k = 0; k < NPTEPG; k++) {
+					if ((pt[k] & PG_V) == PG_V) {
+						pa = pt[k] & PG_FRAME;
+						if (is_dumpable(pa))
+							dump_add_page(pa);
+					}
 				}
 			}
-		} else {
-			/* nothing, we're going to dump a null page */
 		}
 	}
 
 	/* Calculate dump size. */
-	dumpsize = ptesize;
+	dumpsize = pmapsize;
 	dumpsize += round_page(msgbufp->msg_size);
 	dumpsize += round_page(vm_page_dump_size);
 	for (i = 0; i < vm_page_dump_size / sizeof(*vm_page_dump); i++) {
@@ -244,7 +270,7 @@ minidumpsys(struct dumperinfo *di)
 
 	/* Determine dump offset on device. */
 	if (di->mediasize < SIZEOF_METADATA + dumpsize + sizeof(kdh) * 2) {
-		error = ENOSPC;
+		error = E2BIG;
 		goto fail;
 	}
 	dumplo = di->mediaoffset + di->mediasize - dumpsize;
@@ -257,7 +283,7 @@ minidumpsys(struct dumperinfo *di)
 	mdhdr.version = MINIDUMP_VERSION;
 	mdhdr.msgbufsize = msgbufp->msg_size;
 	mdhdr.bitmapsize = vm_page_dump_size;
-	mdhdr.ptesize = ptesize;
+	mdhdr.pmapsize = pmapsize;
 	mdhdr.kernbase = VM_MIN_KERNEL_ADDRESS;
 	mdhdr.dmapbase = DMAP_MIN_ADDRESS;
 	mdhdr.dmapend = DMAP_MAX_ADDRESS;
@@ -274,9 +300,9 @@ minidumpsys(struct dumperinfo *di)
 	dumplo += sizeof(kdh);
 
 	/* Dump my header */
-	bzero(&fakept, sizeof(fakept));
-	bcopy(&mdhdr, &fakept, sizeof(mdhdr));
-	error = blk_write(di, (char *)&fakept, 0, PAGE_SIZE);
+	bzero(&fakepd, sizeof(fakepd));
+	bcopy(&mdhdr, &fakepd, sizeof(mdhdr));
+	error = blk_write(di, (char *)&fakepd, 0, PAGE_SIZE);
 	if (error)
 		goto fail;
 
@@ -290,55 +316,47 @@ minidumpsys(struct dumperinfo *di)
 	if (error)
 		goto fail;
 
-	/* Dump kernel page table pages */
+	/* Dump kernel page directory pages */
+	bzero(fakepd, sizeof(fakepd));
 	pdp = (uint64_t *)PHYS_TO_DMAP(KPDPphys);
 	for (va = VM_MIN_KERNEL_ADDRESS; va < MAX(KERNBASE + NKPT * NBPDR,
-	    kernel_vm_end); va += NBPDR) {
+	    kernel_vm_end); va += NBPDP) {
 		i = (va >> PDPSHIFT) & ((1ul << NPDPEPGSHIFT) - 1);
 		/* We always write a page, even if it is zero */
 		if ((pdp[i] & PG_V) == 0) {
-			bzero(fakept, sizeof(fakept));
-			error = blk_write(di, (char *)&fakept, 0, PAGE_SIZE);
+			error = blk_write(di, (char *)&fakepd, 0, PAGE_SIZE);
 			if (error)
 				goto fail;
-			/* flush, in case we reuse fakept in the same block */
+			/* flush, in case we reuse fakepd in the same block */
 			error = blk_flush(di);
 			if (error)
 				goto fail;
 			continue;
 		}
-		pd = (uint64_t *)PHYS_TO_DMAP(pdp[i] & PG_FRAME);
-		j = ((va >> PDRSHIFT) & ((1ul << NPDEPGSHIFT) - 1));
-		if ((pd[j] & (PG_PS | PG_V)) == (PG_PS | PG_V))  {
-			/* This is a single 2M block. Generate a fake PTP */
-			pa = pd[j] & PG_PS_FRAME;
-			for (k = 0; k < NPTEPG; k++) {
-				fakept[k] = (pa + (k * PAGE_SIZE)) | PG_V | PG_RW | PG_A | PG_M;
-			}
-			error = blk_write(di, (char *)&fakept, 0, PAGE_SIZE);
+		/* 1GB page is represented as 512 2MB pages in a dump */
+		if ((pdp[i] & PG_PS) != 0) {
+			va += NBPDP;
+			pa = pdp[i] & PG_PS_FRAME;
+			for (j = 0; j < NPDEPG; j++)
+				fakepd[j] = (pa + (j  << PDRSHIFT)) | PG_V | PG_PS | PG_RW | PG_A | PG_M;
+			error = blk_write(di, (char *)&fakepd, 0, PAGE_SIZE);
 			if (error)
 				goto fail;
-			/* flush, in case we reuse fakept in the same block */
+			/* flush, in case we reuse fakepd in the same block */
 			error = blk_flush(di);
 			if (error)
 				goto fail;
+			bzero(fakepd, sizeof(fakepd));
 			continue;
 		}
-		if ((pd[j] & PG_V) == PG_V) {
-			pt = (uint64_t *)PHYS_TO_DMAP(pd[j] & PG_FRAME);
-			error = blk_write(di, (char *)pt, 0, PAGE_SIZE);
-			if (error)
-				goto fail;
-		} else {
-			bzero(fakept, sizeof(fakept));
-			error = blk_write(di, (char *)&fakept, 0, PAGE_SIZE);
-			if (error)
-				goto fail;
-			/* flush, in case we reuse fakept in the same block */
-			error = blk_flush(di);
-			if (error)
-				goto fail;
-		}
+
+		pd = (uint64_t *)PHYS_TO_DMAP(pdp[i] & PG_FRAME);
+		error = blk_write(di, (char *)pd, 0, PAGE_SIZE);
+		if (error)
+			goto fail;
+		error = blk_flush(di);
+		if (error)
+			goto fail;
 	}
 
 	/* Dump memory chunks */
@@ -374,12 +392,21 @@ minidumpsys(struct dumperinfo *di)
 	if (error < 0)
 		error = -error;
 
-	if (error == ECANCELED)
-		printf("\nDump aborted\n");
-	else if (error == ENOSPC)
-		printf("\nDump failed. Partition too small.\n");
+	printf("\n");
+	if (error == ENOSPC) {
+		printf("Dump map grown while dumping. ");
+		if (retry_count < 5) {
+			printf("Retrying...\n");
+			goto retry;
+		}
+		printf("Dump failed.\n");
+	}
+	else if (error == ECANCELED)
+		printf("Dump aborted\n");
+	else if (error == E2BIG)
+		printf("Dump failed. Partition too small.\n");
 	else
-		printf("\n** DUMP FAILED (ERROR %d) **\n", error);
+		printf("** DUMP FAILED (ERROR %d) **\n", error);
 }
 
 void
diff --git a/lib/libkvm/kvm_minidump_amd64.c b/lib/libkvm/kvm_minidump_amd64.c
index 8f48f98..15630b1 100644
--- a/lib/libkvm/kvm_minidump_amd64.c
+++ b/lib/libkvm/kvm_minidump_amd64.c
@@ -67,7 +67,7 @@ struct vmstate {
 	struct minidumphdr hdr;
 	void *hpt_head[HPT_SIZE];
 	uint64_t *bitmap;
-	uint64_t *ptemap;
+	uint64_t *page_map;
 };
 
 static void
@@ -127,8 +127,8 @@ _kvm_minidump_freevtop(kvm_t *kd)
 
 	if (vm->bitmap)
 		free(vm->bitmap);
-	if (vm->ptemap)
-		free(vm->ptemap);
+	if (vm->page_map)
+		free(vm->page_map);
 	free(vm);
 	kd->vmst = NULL;
 }
@@ -156,7 +156,12 @@ _kvm_minidump_initvtop(kvm_t *kd)
 		_kvm_err(kd, kd->program, "not a minidump for this platform");
 		return (-1);
 	}
-	if (vmst->hdr.version != MINIDUMP_VERSION) {
+
+	/*
+	 * NB: amd64 minidump header is binary compatible between version 1
+	 * and version 2; this may not be the case for the future versions.
+	 */
+	if (vmst->hdr.version != MINIDUMP_VERSION && vmst->hdr.version != 1) {
 		_kvm_err(kd, kd->program, "wrong minidump version. expected %d got %d",
 		    MINIDUMP_VERSION, vmst->hdr.version);
 		return (-1);
@@ -177,17 +182,17 @@ _kvm_minidump_initvtop(kvm_t *kd)
 	}
 	off += round_page(vmst->hdr.bitmapsize);
 
-	vmst->ptemap = _kvm_malloc(kd, vmst->hdr.ptesize);
-	if (vmst->ptemap == NULL) {
-		_kvm_err(kd, kd->program, "cannot allocate %d bytes for ptemap", vmst->hdr.ptesize);
+	vmst->page_map = _kvm_malloc(kd, vmst->hdr.pmapsize);
+	if (vmst->page_map == NULL) {
+		_kvm_err(kd, kd->program, "cannot allocate %d bytes for page_map", vmst->hdr.pmapsize);
 		return (-1);
 	}
-	if (pread(kd->pmfd, vmst->ptemap, vmst->hdr.ptesize, off) !=
-	    vmst->hdr.ptesize) {
-		_kvm_err(kd, kd->program, "cannot read %d bytes for ptemap", vmst->hdr.ptesize);
+	if (pread(kd->pmfd, vmst->page_map, vmst->hdr.pmapsize, off) !=
+	    vmst->hdr.pmapsize) {
+		_kvm_err(kd, kd->program, "cannot read %d bytes for page_map", vmst->hdr.pmapsize);
 		return (-1);
 	}
-	off += vmst->hdr.ptesize;
+	off += vmst->hdr.pmapsize;
 
 	/* build physical address hash table for sparse pages */
 	inithash(kd, vmst->bitmap, vmst->hdr.bitmapsize, off);
@@ -196,7 +201,7 @@ _kvm_minidump_initvtop(kvm_t *kd)
 }
 
 static int
-_kvm_minidump_vatop(kvm_t *kd, u_long va, off_t *pa)
+_kvm_minidump_vatop_v1(kvm_t *kd, u_long va, off_t *pa)
 {
 	struct vmstate *vm;
 	u_long offset;
@@ -211,7 +216,7 @@ _kvm_minidump_vatop(kvm_t *kd, u_long va, off_t *pa)
 
 	if (va >= vm->hdr.kernbase) {
 		pteindex = (va - vm->hdr.kernbase) >> PAGE_SHIFT;
-		pte = vm->ptemap[pteindex];
+		pte = vm->page_map[pteindex];
 		if (((u_long)pte & PG_V) == 0) {
 			_kvm_err(kd, kd->program, "_kvm_vatop: pte not valid");
 			goto invalid;
@@ -243,6 +248,78 @@ invalid:
 	return (0);
 }
 
+static int
+_kvm_minidump_vatop(kvm_t *kd, u_long va, off_t *pa)
+{
+	pt_entry_t pt[NPTEPG];
+	struct vmstate *vm;
+	u_long offset;
+	pd_entry_t pde;
+	pd_entry_t pte;
+	u_long pteindex;
+	u_long pdeindex;
+	int i;
+	u_long a;
+	off_t ofs;
+
+	vm = kd->vmst;
+	offset = va & PAGE_MASK;
+
+	if (va >= vm->hdr.kernbase) {
+		pdeindex = (va - vm->hdr.kernbase) >> PDRSHIFT;
+		pde = vm->page_map[pdeindex];
+		if (((u_long)pde & PG_V) == 0) {
+			_kvm_err(kd, kd->program, "_kvm_vatop: pde not valid");
+			goto invalid;
+		}
+		if ((pde & PG_PS) == 0) {
+			a = pde & PG_FRAME;
+			ofs = hpt_find(kd, a);
+			if (ofs == -1) {
+				_kvm_err(kd, kd->program, "_kvm_vatop: pt physical address 0x%lx not in minidump", a);
+				goto invalid;
+			}
+			if (pread(kd->pmfd, &pt, PAGE_SIZE, ofs) != PAGE_SIZE) {
+				_kvm_err(kd, kd->program, "cannot read %d bytes for pt", PAGE_SIZE);
+				return (-1);
+			}
+			pteindex = (va >> PAGE_SHIFT) & ((1ul << NPTEPGSHIFT) - 1);
+			pte = pt[pteindex];
+			if (((u_long)pte & PG_V) == 0) {
+				_kvm_err(kd, kd->program, "_kvm_vatop: pte not valid");
+				goto invalid;
+			}
+			a = pte & PG_FRAME;
+		} else {
+			a = pde & PG_PS_FRAME;
+			a += (va & PDRMASK) ^ offset;
+		}
+		ofs = hpt_find(kd, a);
+		if (ofs == -1) {
+			_kvm_err(kd, kd->program, "_kvm_vatop: physical address 0x%lx not in minidump", a);
+			goto invalid;
+		}
+		*pa = ofs + offset;
+		return (PAGE_SIZE - offset);
+	} else if (va >= vm->hdr.dmapbase && va < vm->hdr.dmapend) {
+		a = (va - vm->hdr.dmapbase) & ~PAGE_MASK;
+		ofs = hpt_find(kd, a);
+		if (ofs == -1) {
+			_kvm_err(kd, kd->program, "_kvm_vatop: direct map address 0x%lx not in minidump", va);
+			goto invalid;
+		}
+		*pa = ofs + offset;
+		return (PAGE_SIZE - offset);
+	} else {
+		_kvm_err(kd, kd->program, "_kvm_vatop: virtual address 0x%lx not minidumped", va);
+		goto invalid;
+	}
+
+invalid:
+	_kvm_err(kd, 0, "invalid address (0x%lx)", va);
+	return (0);
+}
+
 int
 _kvm_minidump_kvatop(kvm_t *kd, u_long va, off_t *pa)
 {
@@ -251,5 +328,8 @@ _kvm_minidump_kvatop(kvm_t *kd, u_long va, off_t *pa)
 		_kvm_err(kd, 0, "kvm_kvatop called in live kernel!");
 		return (0);
 	}
-	return (_kvm_minidump_vatop(kd, va, pa));
+	if (((struct vmstate *)kd->vmst)->hdr.version == 1)
+		return (_kvm_minidump_vatop_v1(kd, va, pa));
+	else
+		return (_kvm_minidump_vatop(kd, va, pa));
 }