On Wednesday, 14 June 2023 01:21:53 BST Philip Webb wrote:
> My new machine has no problem with graphics using System Rescue etc
> nor using 'startx' as root with Gentoo, but it refuses to start as user.
> 
> I've had a series of errors :
> 
>   parse_vt_settings : can't open /dev/tty0 (permission denied)
> 
> after adding my user to 'tty input' in 'group' :
> 
>   can't open virtual console 7 : permission denied

Not sure if this is necessary:

$ grep 'tty|input' /etc/group
tty:x:5:
input:x:97:


> after adding 'elogind' to 'default' runlevel & starting it :
> 
>   xf86EnableIO : failed to enable I/O ports 0000-03ff
>    (operation not permitted)

The elogind service ought to be in boot runlevel according to the wiki:

https://wiki.gentoo.org/wiki/Elogind#Configuration


> yes, my user is in the 'video' group & 'xorg-server' has  USE="elogind" .
> 
> In my current machine, there is a  /dev/fb0  with permission  660 .
> but there is no such device in the new machine.

Have you followed this wiki page to configure your kernel, include the 
appropriate firmware for your card(s), set up INPUT_DEVICES & VIDEO_CARDS in 
make.conf, emerge associated x11-base/xorg-drivers and the x11-base/xorg-
server packages before a reboot?

https://wiki.gentoo.org/wiki/Xorg/Guide

There should be a fb0 device listed:

$ ls -l /dev/fb*
crw-rw---- 1 root video 29, 0 Jun 14 08:52 /dev/fb0

You'll also need to have emerged a Desktop Environment, or at least a window 
manager:

https://wiki.gentoo.org/wiki/Window_manager

Check the above wiki pages and post back with any queries and accompanying 
logs if things do not work as expected.