Comment 15 for bug 1815002

I'm not convinced the keypress is 100% reliable. It does get better all the time, but there are still systems on which it's just not possible to get it working reliably, and sometimes not at all - you'll press consistantly "too late" or "to early" and GRUB won't notice, so you won't get the menu.

AIUI, the issue came from EFI timers being odd, but I can't qualify that: TSC calibration isn't done using the EFI timer first -- we first look at pmtimer and PIT before we use the EFI timers.

As for / on btrfs, I agree it's a side-effect of the check_writable() call, but it does seem to still be "up to date" at first glance: it's *supposed* to be affected the same way: if you're on a system on which the keypress doesn't get you the menu (this is system-specific), *and* you're set up with /boot on btrfs (which doesn't have write support as far as I can tell), then a failing boot won't get you the menu automatically. So... three machines is good, but if they're all the same kind (all Dell, all AMI, etc.) then it might not be a good sample.

I think the point is that we need a better idea of exactly which systems are affected, to try and tell how many people it really affects. Let's try to get that now.

Steve, do we have a good list of exactly which systems we've seen the LVM issues on?