Mobile site on a subdomain

#1
Hello!
By inserting a meta tag on the main version of the site
Code:
<link rel = "alternate" media = "only screen and (max-width: 640px)" href = "https://m.site.ru/">
It must necessarily be for each page its own with its address, or is it possible for several pages of one subsection to put one URL of their common page a level higher, from which links to all the others go?

thanks