There are three mechanisms for allocating unmanaged memory:

* sysAlloc obtains memory directly from the OS. This comes in whole
  multiples of the system page size, but it can be freed with sysFree.

* persistentalloc combines multiple smaller allocations into a single
  sysAlloc to avoid fragmentation. However, there is no way to free
  persistentalloced objects (hence the name).

			hintList = &h.arenaHints
		}
		v, size := h.sysAlloc(userArenaChunkBytes, hintList, false)
		if size%userArenaChunkBytes != 0 {
			throw("sysAlloc size is not divisible by userArenaChunkBytes")
		}
		if size > userArenaChunkBytes {
			// We got more than we asked for. This can happen if
			// heapArenaSize > userArenaChunkSize, or if sysAlloc just returns

		throw("newosproc")
	}
}

// Version of newosproc that doesn't require a valid G.
//
//go:nosplit
func newosproc0(stacksize uintptr, fn unsafe.Pointer) {
	stack := sysAlloc(stacksize, &memstats.stacks_sys)
	if stack == nil {
		writeErrStr(failallocatestack)
		exit(1)
	}
	// This code "knows" it's being called once from the library

		t.FailNow()
	}
}

type acLink struct {
	x [1 << 20]byte
}

var arenaCollisionSink []*acLink

func TestArenaCollision(t *testing.T) {
	testenv.MustHaveExec(t)

	// Test that mheap.sysAlloc handles collisions with other
	// memory mappings.
	if os.Getenv("TEST_ARENA_COLLISION") != "1" {
		cmd := testenv.CleanCmdEnv(exec.Command(os.Args[0], "-test.run=^TestArenaCollision$", "-test.v"))

		n := 64 * 1024 / goarch.PtrSize
		if n < cap(h.allspans)*3/2 {
			n = cap(h.allspans) * 3 / 2
		}
		var new []*mspan
		sp := (*slice)(unsafe.Pointer(&new))
		sp.array = sysAlloc(uintptr(n)*goarch.PtrSize, &memstats.other_sys)
		if sp.array == nil {
			throw("runtime: cannot allocate memory")
		}
		sp.len = len(h.allspans)
		sp.cap = n
		if len(h.allspans) > 0 {

	nptr := size / goarch.PtrSize
	if uintptr(len(tmpbuf)) < nptr/8+1 {
		if tmpbuf != nil {
			sysFree(unsafe.Pointer(&tmpbuf[0]), uintptr(len(tmpbuf)), &memstats.other_sys)
		}
		n := nptr/8 + 1
		p := sysAlloc(n, &memstats.other_sys)
		if p == nil {
			throw("heapdump: out of memory")
		}
		tmpbuf = (*[1 << 30]byte)(p)[:n]
	}
	// Convert heap bitmap to pointer bitmap.
	clear(tmpbuf[:nptr/8+1])
	s := spanOf(p)

	}
	return
}
func osinit_hack_trampoline()

// mmap is used to do low-level memory allocation via mmap. Don't allow stack
// splits, since this function (used by sysAlloc) is called in a lot of low-level
// parts of the runtime and callers often assume it won't acquire any locks.
//
//go:nosplit

		}
		throw("newosproc")
	}
}

// Version of newosproc that doesn't require a valid G.
//
//go:nosplit
func newosproc0(stacksize uintptr, fn unsafe.Pointer) {
	stack := sysAlloc(stacksize, &memstats.stacks_sys)
	if stack == nil {
		writeErrStr(failallocatestack)
		exit(1)
	}
	ret := clone(cloneFlags, unsafe.Pointer(uintptr(stack)+stacksize), nil, nil, fn)
	if ret < 0 {

		throw("stack size not a power of 2")
	}
	if stackDebug >= 1 {
		print("stackalloc ", n, "\n")
	}

	if debug.efence != 0 || stackFromSystem != 0 {
		n = uint32(alignUp(uintptr(n), physPageSize))
		v := sysAlloc(uintptr(n), &memstats.stacks_sys)
		if v == nil {
			throw("out of memory (stackalloc)")
		}
		return stack{uintptr(v), uintptr(v) + uintptr(n)}
	}

	for c := chunkIndex(base); c < chunkIndex(limit); c++ {
		if p.chunks[c.l1()] == nil {
			// Create the necessary l2 entry.
			const l2Size = unsafe.Sizeof(*p.chunks[0])
			r := sysAlloc(l2Size, p.sysStat)
			if r == nil {
				throw("pageAlloc: out of memory")
			}
			if !p.test {
				// Make the chunk mapping eligible or ineligible
				// for huge pages, depending on what our current