Features:
+* support uefi/http boots with sd-boot: instead of looking for dropin files in
+ /loader/entries/ dir, look for a file /loader/entries/SHA256SUMS and use that
+ as directory manifest. The file would be a standard directory listing as
+ generated by GNU sha256sums.
+
* initialize machine ID from systemd credential picked up from the ESP via
sd-stub, so that machine ID is stable even on systems where unified kernels
are used, and hence kernel cmdline cannot be modified locally