As explained on the site, yes, but if you are running an older kernel you need to use the individual flags instead, and since the kernel safely ignores any flag

As explained on the site, yes, but if you are running an older kernel you need to use the individual flags instead, and since the kernel safely ignores any flags it doesn't recognize, the full string works for everyone and doesn't do any harm. (Other than turning mitigations off, ofc...)