I tried to find out why wmidell doesn't attach on my R6515, and found out that while I do have WMI_DELL_GUID_DESC (8D9DDCBC-A997-11DA-B012-B622A1EF5492), I don't have WMI_DELL_GUID_EVENT (9DBB5994-A997-11DA-B012-B622A1EF5492), and wmi_dell.c will only match if the latter is present (while it seems to only use the former).