Filed both XO related issues:
Memory visibility at VM creation: https://github.com/vatesfr/xen-orchestra/issues/10225
domain_crash invisible in XO: https://github.com/vatesfr/xen-orchestra/issues/10226
Linking to this thread as promised earlier, thanks all. Hope this helps someone out.
This might have worked, at that time i've allready created new VMs from the information inside the Backup xml file. It worked out allright but building VMs this way, is quite tidious.
Maybe there could be a way to find the correct installer and patches, to get a new host in a state to restore a pool backup, would be good.
Du coup j'ai testé avec RHEL 9, ça fonctionne aussi.
Faut bien prendre l'iso "dvd", pas "boot" en revanche ! (je me suis fait avoir en téléchargeant l'image)