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

	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("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)}
	}

	testSysStat.add(-int64(p.summaryMappedReady))

	// Free the mapped space for chunks.
	for i := range p.chunks {
		if x := p.chunks[i]; x != nil {
			p.chunks[i] = nil
			// This memory comes from sysAlloc and will always be page-aligned.
			sysFree(unsafe.Pointer(x), unsafe.Sizeof(*p.chunks[0]), testSysStat)
		}
	}
}

// BaseChunkIdx is a convenient chunkIdx value which works on both