Function: scroll-all-mode

Toggle shared scrolling in same-frame windows (Scroll-All mode).
With a prefix argument ARG, enable Scroll-All mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.

When Scroll-All mode is enabled, scrolling commands invoked in
one window apply to all visible windows in the same frame. (fn &optional ARG)

Variable: scroll-all-mode

Non-nil if Scroll-All mode is enabled.
See the command `scroll-all-mode' for a description of this minor mode.
Setting this variable directly does not take effect;
either customize it (see the info node `Easy Customization')
or call the function `scroll-all-mode'.