Finally i succeeded in installing a devuan ascii into qemu (running on
an archlinux openrc system).
And here too, i noticed that the debian installer is somehow "extreme"
in using ressources. Note this is *NOT* an amd graphics based machine
but a sony_vaio with nvidia graphics. (On another laptop, a samsung
with amd processor and graphics, i could not get installed devuan until
i did not put the machine on top of an icepack!!!).
But nevertheless, installing devuan also this vaio heats up to
something like 85° - but it has a stronger fan than, so the
process went through.
I'm wondering why this problems do not happen with installers of other
distros. If this is repeatable for others too, may be, if some one is
able and prepared to do that, it might be good to check, if there is a
reason why (?)