runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setKeepAliveInterval(fd *netFD, d time.Duration) error {
	if !unix.SupportTCPKeepAliveIdleIntvlCNT() {
		return syscall.EPROTOTYPE
	}

	if d == 0 {
		d = defaultTCPKeepAliveInterval
	} else if d < 0 {
		return nil
	}
	// The kernel expects seconds so round to next highest second.
	secs := int(roundDurationUp(d, time.Second))

	EOVERFLOW       = syscall.Errno(0x4b)
	EOWNERDEAD      = syscall.Errno(0x82)
	EPFNOSUPPORT    = syscall.Errno(0x60)
	EPROTO          = syscall.Errno(0x47)
	EPROTONOSUPPORT = syscall.Errno(0x5d)
	EPROTOTYPE      = syscall.Errno(0x5b)
	EREMCHG         = syscall.Errno(0x4e)
	EREMOTE         = syscall.Errno(0x42)
	EREMOTEIO       = syscall.Errno(0x79)
	ERESTART        = syscall.Errno(0x55)

	EOVERFLOW       = syscall.Errno(0x4b)
	EOWNERDEAD      = syscall.Errno(0x82)
	EPFNOSUPPORT    = syscall.Errno(0x60)
	EPROTO          = syscall.Errno(0x47)
	EPROTONOSUPPORT = syscall.Errno(0x5d)
	EPROTOTYPE      = syscall.Errno(0x5b)
	EREMCHG         = syscall.Errno(0x4e)
	EREMOTE         = syscall.Errno(0x42)
	EREMOTEIO       = syscall.Errno(0x79)
	ERESTART        = syscall.Errno(0x55)

	EOVERFLOW       = syscall.Errno(0x4b)
	EOWNERDEAD      = syscall.Errno(0x82)
	EPFNOSUPPORT    = syscall.Errno(0x60)
	EPROTO          = syscall.Errno(0x47)
	EPROTONOSUPPORT = syscall.Errno(0x5d)
	EPROTOTYPE      = syscall.Errno(0x5b)
	EREMCHG         = syscall.Errno(0x4e)
	EREMOTE         = syscall.Errno(0x42)
	EREMOTEIO       = syscall.Errno(0x79)
	ERESTART        = syscall.Errno(0x55)

	EWOULDBLOCK        = Errno(1102)
	EINPROGRESS        = Errno(1103)
	EALREADY           = Errno(1104)
	ENOTSOCK           = Errno(1105)
	EDESTADDRREQ       = Errno(1106)
	EMSGSIZE           = Errno(1107)
	EPROTOTYPE         = Errno(1108)
	ENOPROTOOPT        = Errno(1109)
	EPROTONOSUPPORT    = Errno(1110)
	ESOCKTNOSUPPORT    = Errno(1111)
	EOPNOTSUPP         = Errno(1112)
	EPFNOSUPPORT       = Errno(1113)

	EOWNERDEAD      = Errno(0x3a)
	EPERM           = Errno(0x1)
	EPFNOSUPPORT    = Errno(0x7b)
	EPIPE           = Errno(0x20)
	EPROTO          = Errno(0x47)
	EPROTONOSUPPORT = Errno(0x78)
	EPROTOTYPE      = Errno(0x62)
	ERANGE          = Errno(0x22)
	EREMCHG         = Errno(0x52)
	EREMOTE         = Errno(0x42)
	ERESTART        = Errno(0x5b)
	EROFS           = Errno(0x1e)
	ESHUTDOWN       = Errno(0x8f)