drop you into a shell after the installation finished, where you can upgrade the systemd package(s).
Is there a process described anywhere for doing this? I pulled the latest systemd-boot & -boot-efi debs from the repository, but I don't think it's as simple a matter as "dpkg -i <deb>"
Edit: I was able to chroot into a fresh install using [most of] the steps listed
here, then manually installed libsystemd-shared (dependency), systemd-boot, and systemd-boot-efi packages from the
no-sub repository, all version 252.11-pve1 (which includes the "small chunks" backport). Ran "pve-efiboot-tool refresh" afterwards, then backed-out and rebooted, but it didn't help, still getting "Bad Buffer Size" error on boot.
Is there a step I may have missed?
Edit 2: In the interest of trying everything, I booted up the PVE8 install media, dropped to shell, chrooted back into the previously mentioned install of PVE8, and after getting a rudimentary network connection up, did an "apt-get update/upgrade" against the debian bookworm & pve-no-sub repositories. After repairing the install of the systemd 252.11-pve1 debs I installed earlier (version mismatch, fixed with "apt-get --fix-broken install"), the upgrade completed without incident. (For the record, the systemd-* packages installed at this point are 252.12-pmx1). Ran "proxmox-boot-tool refresh" again, because why not. Backed-out of the chroot, rebooted, and it still doesn't work.