err := ctxt.Out.Mmap(uint64(filesz))
	if err != nil {
		Exitf("mapping output file failed: %v", err)
	}
}

// relocSectFn wraps the function writing relocations of a section
// for parallel execution. Returns the wrapped function and a wait
// group for which the caller should wait.
func relocSectFn(ctxt *Link, relocSect func(*Link, *OutBuf, *sym.Section, []loader.Sym)) (func(*Link, *sym.Section, []loader.Sym), *sync.WaitGroup) {

	}
}

func machoEmitReloc(ctxt *Link) {
	for ctxt.Out.Offset()&7 != 0 {
		ctxt.Out.Write8(0)
	}

	sizeExtRelocs(ctxt, thearch.MachorelocSize)
	relocSect, wg := relocSectFn(ctxt, machorelocsect)

	relocSect(ctxt, Segtext.Sections[0], ctxt.Textp)
	for _, sect := range Segtext.Sections[1:] {
		if sect.Name == ".text" {
			relocSect(ctxt, sect, ctxt.Textp)
		} else {

	}
}

func elfEmitReloc(ctxt *Link) {
	for ctxt.Out.Offset()&7 != 0 {
		ctxt.Out.Write8(0)
	}

	sizeExtRelocs(ctxt, thearch.ELF.RelocSize)
	relocSect, wg := relocSectFn(ctxt, elfrelocsect)

	for _, sect := range Segtext.Sections {
		if sect.Name == ".text" {
			relocSect(ctxt, sect, ctxt.Textp)
		} else {
			relocSect(ctxt, sect, ctxt.datap)
		}
	}