Hi 白い熊,

白い熊 写道：
> file root to specify this config in an (extra-special-file 
> statement,
> so that it'd be picked up on login and GDM would be properly 
> rotated?

*Must* it use extra-special-file?  If so, why?  You can try it 
 (untested):

  (extra-special-file "/etc/X11/xorg.conf.d/01-monitor.conf"
                      "Section \"Monitor\" blah blah blah")

and see if Guix's Xorg looks in /etc/X11/xorg.conf.d at all.

Instead, what I'd use is (untested):

(services […]
          (set-xorg-configuration
            (xorg-configuration
              ;; You might have a keyboard-layout
              ;; here already, for example.
              […]
              (extra-config "
Section \"Monitor\"
    Identifier \"DSI-1\"
    Option \"Rotate\" \"right\"
EndSection")))
          …)

> As a side note - and might be associated with this - can a small
> resolution be specified for just the GDM login screen - because 
> on
> this computer the screen is tiny, the resolution big and thus 
> the GDM
> login screen is with super tiny font everywhere.

That I don't know, but it's a similar ‘just create a file in 
/usr!’ mess, according to several pages like 
<https://misperious.wordpress.com/2019/11/23/gdm-hidpi-scaling/>.

I don't know how to Guixify *that*.

Kind regards,

T G-R