diff --git a/golang.spec b/golang.spec
index 35b1d60..28a159a 100644
--- a/golang.spec
+++ b/golang.spec
@@ -86,7 +86,7 @@
 
 Name:           golang
 Version:        1.6.3
-Release:        2%{?dist}
+Release:        3%{?dist}
 Summary:        The Go Programming Language
 # source tree includes several copies of Mark.Twain-Tom.Sawyer.txt under Public Domain
 License:        BSD and Public Domain
@@ -128,6 +128,9 @@ Patch213:       go1.5beta1-disable-TestGdbPython.patch
 # later run `go test -a std`. This makes it only use the zoneinfo.zip where needed in tests.
 Patch215:       ./go1.5-zoneinfo_testing_only.patch
 
+# Backport of https://go-review.googlesource.com/#/c/20471/
+Patch216:       runtime-use-entire-address-space-on-32-bit.patch
+
 # Having documentation separate was broken
 Obsoletes:      %{name}-docs < 1.1-4
 
@@ -253,6 +256,8 @@ Summary:        Golang shared object libraries
 
 %patch215 -p1
 
+%patch216 -p1
+
 %build
 # print out system information
 uname -a
@@ -457,6 +462,9 @@ fi
 %endif
 
 %changelog
+* Tue Sep 27 2016 Jakub Čajka <jcajka@redhat.com> - 1.6.3-3
+- Resolves: BZ#1378960 - make possible to use whole address space on 32bit
+
 * Mon Aug 08 2016 Jakub Čajka <jcajka@redhat.com> - 1.6.3-2
 - Obsolete golang-vet and golang-cover from golang-googlecode-tools package
   vet/cover binaries are provided by golang-bin rpm(thanks to jchaloup)
diff --git a/runtime-use-entire-address-space-on-32-bit.patch b/runtime-use-entire-address-space-on-32-bit.patch
new file mode 100644
index 0000000..d27ef51
--- /dev/null
+++ b/runtime-use-entire-address-space-on-32-bit.patch
@@ -0,0 +1,234 @@
+diff --git a/src/runtime/cgocall.go b/src/runtime/cgocall.go
+index fef8add..30c3a67 100644
+--- a/src/runtime/cgocall.go
++++ b/src/runtime/cgocall.go
+@@ -568,7 +568,7 @@ func cgoIsGoPointer(p unsafe.Pointer) bool {
+ 		return false
+ 	}
+ 
+-	if cgoInRange(p, mheap_.arena_start, mheap_.arena_used) {
++	if inHeapOrStack(uintptr(p)) {
+ 		return true
+ 	}
+ 
+diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
+index b520c68..2055da5 100644
+--- a/src/runtime/malloc.go
++++ b/src/runtime/malloc.go
+@@ -173,7 +173,7 @@ const (
+ // Page number (address>>pageShift)
+ type pageID uintptr
+ 
+-const _MaxArena32 = 2 << 30
++const _MaxArena32 = 1<<32 - 1
+ 
+ // OS-defined helpers:
+ //
+@@ -230,7 +230,7 @@ func mallocinit() {
+ 
+ 	// Set up the allocation arena, a contiguous area of memory where
+ 	// allocated data will be found.  The arena begins with a bitmap large
+-	// enough to hold 4 bits per allocated word.
++	// enough to hold 2 bits per allocated word.
+ 	if sys.PtrSize == 8 && (limit == 0 || limit > 1<<30) {
+ 		// On a 64-bit machine, allocate from a single contiguous reservation.
+ 		// 512 GB (MaxMem) should be big enough for now.
+@@ -262,7 +262,7 @@ func mallocinit() {
+ 		// translation buffers, the user address space is limited to 39 bits
+ 		// On darwin/arm64, the address space is even smaller.
+ 		arenaSize := round(_MaxMem, _PageSize)
+-		bitmapSize = arenaSize / (sys.PtrSize * 8 / 4)
++		bitmapSize = arenaSize / (sys.PtrSize * 8 / 2)
+ 		spansSize = arenaSize / _PageSize * sys.PtrSize
+ 		spansSize = round(spansSize, _PageSize)
+ 		for i := 0; i <= 0x7f; i++ {
+@@ -287,7 +287,7 @@ func mallocinit() {
+ 		// with a giant virtual address space reservation.
+ 		// Instead we map the memory information bitmap
+ 		// immediately after the data segment, large enough
+-		// to handle another 2GB of mappings (256 MB),
++		// to handle the entire 4GB of mappings (256 MB),
+ 		// along with a reservation for an initial arena.
+ 		// When that gets used up, we'll start asking the kernel
+ 		// for any memory anywhere and hope it's in the 2GB
+@@ -304,15 +304,18 @@ func mallocinit() {
+ 		// If we fail to allocate, try again with a smaller arena.
+ 		// This is necessary on Android L where we share a process
+ 		// with ART, which reserves virtual memory aggressively.
++		// In the worst case, fall back to a 0-sized initial arena,
++		// in the hope that subsequent reservations will succeed.
+ 		arenaSizes := []uintptr{
+ 			512 << 20,
+ 			256 << 20,
+ 			128 << 20,
++			0,
+ 		}
+ 
+ 		for _, arenaSize := range arenaSizes {
+-			bitmapSize = _MaxArena32 / (sys.PtrSize * 8 / 4)
+-			spansSize = _MaxArena32 / _PageSize * sys.PtrSize
++			bitmapSize = (_MaxArena32 + 1) / (sys.PtrSize * 8 / 2)
++			spansSize = (_MaxArena32 + 1) / _PageSize * sys.PtrSize
+ 			if limit > 0 && arenaSize+bitmapSize+spansSize > limit {
+ 				bitmapSize = (limit / 9) &^ ((1 << _PageShift) - 1)
+ 				arenaSize = bitmapSize * 8
+@@ -347,10 +350,16 @@ func mallocinit() {
+ 	p1 := round(p, _PageSize)
+ 
+ 	mheap_.spans = (**mspan)(unsafe.Pointer(p1))
+-	mheap_.bitmap = p1 + spansSize
+-	mheap_.arena_start = p1 + (spansSize + bitmapSize)
+-	mheap_.arena_used = mheap_.arena_start
++	mheap_.bitmap = p1 + spansSize + bitmapSize
++	if sys.PtrSize == 4 {
++		// Set arena_start such that we can accept memory
++		// reservations located anywhere in the 4GB virtual space.
++		mheap_.arena_start = 0
++	} else {
++		mheap_.arena_start = p1 + (spansSize + bitmapSize)
++	}
+ 	mheap_.arena_end = p + pSize
++	mheap_.arena_used = p1 + (spansSize + bitmapSize)
+ 	mheap_.arena_reserved = reserved
+ 
+ 	if mheap_.arena_start&(_PageSize-1) != 0 {
+@@ -364,36 +373,13 @@ func mallocinit() {
+ 	_g_.m.mcache = allocmcache()
+ }
+ 
+-// sysReserveHigh reserves space somewhere high in the address space.
+-// sysReserve doesn't actually reserve the full amount requested on
+-// 64-bit systems, because of problems with ulimit. Instead it checks
+-// that it can get the first 64 kB and assumes it can grab the rest as
+-// needed. This doesn't work well with the "let the kernel pick an address"
+-// mode, so don't do that. Pick a high address instead.
+-func sysReserveHigh(n uintptr, reserved *bool) unsafe.Pointer {
+-	if sys.PtrSize == 4 {
+-		return sysReserve(nil, n, reserved)
+-	}
+-
+-	for i := 0; i <= 0x7f; i++ {
+-		p := uintptr(i)<<40 | uintptrMask&(0x00c0<<32)
+-		*reserved = false
+-		p = uintptr(sysReserve(unsafe.Pointer(p), n, reserved))
+-		if p != 0 {
+-			return unsafe.Pointer(p)
+-		}
+-	}
+-
+-	return sysReserve(nil, n, reserved)
+-}
+-
+ func (h *mheap) sysAlloc(n uintptr) unsafe.Pointer {
+ 	if n > h.arena_end-h.arena_used {
+ 		// We are in 32-bit mode, maybe we didn't use all possible address space yet.
+ 		// Reserve some more space.
+ 		p_size := round(n+_PageSize, 256<<20)
+ 		new_end := h.arena_end + p_size // Careful: can overflow
+-		if h.arena_end <= new_end && new_end <= h.arena_start+_MaxArena32 {
++		if h.arena_end <= new_end && new_end-h.arena_start-1 <= _MaxArena32 {
+ 			// TODO: It would be bad if part of the arena
+ 			// is reserved and part is not.
+ 			var reserved bool
+@@ -404,7 +390,7 @@ func (h *mheap) sysAlloc(n uintptr) unsafe.Pointer {
+ 			if p == h.arena_end {
+ 				h.arena_end = new_end
+ 				h.arena_reserved = reserved
+-			} else if h.arena_start <= p && p+p_size <= h.arena_start+_MaxArena32 {
++			} else if h.arena_start <= p && p+p_size-h.arena_start-1 <= _MaxArena32 {
+ 				// Keep everything page-aligned.
+ 				// Our pages are bigger than hardware pages.
+ 				h.arena_end = p + p_size
+@@ -441,23 +427,24 @@ func (h *mheap) sysAlloc(n uintptr) unsafe.Pointer {
+ 	}
+ 
+ 	// If using 64-bit, our reservation is all we have.
+-	if h.arena_end-h.arena_start >= _MaxArena32 {
++	if h.arena_end-h.arena_start > _MaxArena32 {
+ 		return nil
+ 	}
+ 
+ 	// On 32-bit, once the reservation is gone we can
+ 	// try to get memory at a location chosen by the OS
+ 	// and hope that it is in the range we allocated bitmap for.
++	// try to get memory at a location chosen by the OS.
+ 	p_size := round(n, _PageSize) + _PageSize
+ 	p := uintptr(sysAlloc(p_size, &memstats.heap_sys))
+ 	if p == 0 {
+ 		return nil
+ 	}
+ 
+-	if p < h.arena_start || uintptr(p)+p_size-h.arena_start >= _MaxArena32 {
++	if p < h.arena_start || p+p_size-h.arena_start > _MaxArena32 {
+ 		top := ^uintptr(0)
+-		if top-h.arena_start > _MaxArena32 {
+-			top = h.arena_start + _MaxArena32
++		if top-h.arena_start-1 > _MaxArena32 {
++			top = h.arena_start + _MaxArena32 + 1
+ 		}
+ 		print("runtime: memory allocated by OS (", hex(p), ") not in usable range [", hex(h.arena_start), ",", hex(top), ")\n")
+ 		sysFree(unsafe.Pointer(p), p_size, &memstats.heap_sys)
+diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
+index 336d4d8..9a5d83b 100644
+--- a/src/runtime/mbitmap.go
++++ b/src/runtime/mbitmap.go
+@@ -145,7 +145,7 @@ func (h *mheap) mapBits(arena_used uintptr) {
+ 		return
+ 	}
+ 
+-	sysMap(unsafe.Pointer(h.arena_start-n), n-h.bitmap_mapped, h.arena_reserved, &memstats.gc_sys)
++	sysMap(unsafe.Pointer(h.bitmap-n), n-h.bitmap_mapped, h.arena_reserved, &memstats.gc_sys)
+ 	h.bitmap_mapped = n
+ }
+ 
+@@ -166,7 +166,7 @@ type heapBits struct {
+ func heapBitsForAddr(addr uintptr) heapBits {
+ 	// 2 bits per work, 4 pairs per byte, and a mask is hard coded.
+ 	off := (addr - mheap_.arena_start) / sys.PtrSize
+-	return heapBits{(*uint8)(unsafe.Pointer(mheap_.arena_start - off/4 - 1)), uint32(off & 3)}
++	return heapBits{(*uint8)(unsafe.Pointer(mheap_.bitmap - off/4 - 1)), uint32(off & 3)}
+ }
+ 
+ // heapBitsForSpan returns the heapBits for the span base address base.
+diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
+index a153df0..1db6a49 100644
+--- a/src/runtime/mheap.go
++++ b/src/runtime/mheap.go
+@@ -46,7 +46,7 @@ type mheap struct {
+ 	nsmallfree [_NumSizeClasses]uint64 // number of frees for small objects (<=maxsmallsize)
+ 
+ 	// range of addresses we might see in the heap
+-	bitmap         uintptr
++	bitmap         uintptr // Points to one byte past the end of the bitmap
+ 	bitmap_mapped  uintptr
+ 	arena_start    uintptr
+ 	arena_used     uintptr // always mHeap_Map{Bits,Spans} before updating
+@@ -217,6 +217,28 @@ func inheap(b uintptr) bool {
+ 	return true
+ }
+ 
++// inHeapOrStack is a variant of inheap that returns true for pointers into stack spans.
++//go:nowritebarrier
++//go:nosplit
++func inHeapOrStack(b uintptr) bool {
++	if b == 0 || b < mheap_.arena_start || b >= mheap_.arena_used {
++		return false
++	}
++	// Not a beginning of a block, consult span table to find the block beginning.
++	s := h_spans[(b-mheap_.arena_start)>>_PageShift]
++	if s == nil || b < s.base() {
++		return false
++	}
++	switch s.state {
++	case mSpanInUse:
++		return b < s.limit
++	case _MSpanStack:
++		return b < s.base()+s.npages<<_PageShift
++	default:
++		return false
++	}
++}
++
+ // TODO: spanOf and spanOfUnchecked are open-coded in a lot of places.
+ // Use the functions instead.
+