Paul and Lurie, Many thanks to you both for the pointers. I retried the update_grub and it worked - I have a nicely-booting nv_90 update now. I have no idea why it failed silently the first time I tried it. But I also had an inexplicable panic in a mutex routine this afternoon when quitting from kmdb (quit from kmdb, panic, drop into kmdb, quit from kmdb, panic, drop into kmdb...etc.); so maybe today wasn't the day for everything working to plan.
Thanks again... Sean.
