Un-mute console on root mount failure

[ali.abdallah_suse.com]

Summary

When boot_mute is set to yes in loader.conf, any root mount failure messages are not shown. I noticed this on one of my system where zfs failed to export zroot, but since boot_mute was set to TRUE, the system just hanged without showing the messages from vfs_mountroot

I believe the console should be unmuted in other cases as well (panic during boot for example).

[emaste]

@imp this seems generally reasonable to me, although we might want a three-state setting, no mute, mute until error, mute always?

kern/kern_cons.c

573–574

Why check first?

[imp]

@imp this seems generally reasonable to me, although we might want a three-state setting, no mute, mute until error, mute always?

So we know some errors, but generally, I think this isn't quite ready. At a minimum we shouldn't necessarily unmute here, since that makes it unconditional and further kernel messages are always printed. If we want to unmute for errors, then there's a tiny number of things. that are unmute worthy. panic, password prompt and can't mount root. I can't think of any others. And the 'prompt for password' thing maybe should just unmute for that.

So I'm uneasy about this in it's current form.

kern/kern_cons.c

573–574

Yea, this should be unconditional.