revisiting tunables under Safe Mode menu option

Devin Teske devin.teske at
Thu Mar 1 16:52:42 UTC 2012

> -----Original Message-----
> From: Andriy Gapon [mailto:avg at]
> Sent: Thursday, March 01, 2012 12:39 AM
> To: Devin Teske
> Cc: John Baldwin; freebsd-current at; Scott Long; Devin Teske
> Subject: Re: revisiting tunables under Safe Mode menu option
> on 01/03/2012 03:34 Devin Teske said the following:
> >
> > +1 on keeping the menu items loosely entwined (ACPI stands alone, but Safe
> > Mode knows about ACPI but only acts on it when being enabled).
> Can you explain why?
> +1 for having both menu items and each doing its own thing without any
> entanglement :-)

First, I realize that this may sound entirely *dumb*, but here-goes:

In transitioning from an old release (sans-menu; 4.11 for example) to a newer
release (with menu; 6.x for example), one of the first thing that is noticed is
"Safe Mode".

I know that when I first saw this, I scratched my head and wondered what it did
and what it might be useful for. To this day, I still have never used it.

When I created the new menu for 9.x/higher, I had to rewrite that portion of the
code and eventually learned what Safe Mode does when used. Still can't say that
I've ever used it, however, at the point that I saw that it disabled ACPI among
other things, that it is more of a blanket option for anything and everything
that might be useful if/when you're having problems (*cough* still can't say
that I've ever used it, as when I have problems I'm usually slogging through the
kernel code, not relying on safe mode to fix some problem).

That being said, I felt that it was a huge improvement to the UI to have the
Safe Mode option divulge a little bit of its secret by visibly diddling the ACPI
menu item (giving a clue to people that *haven't* read the code that this option
is indeed not independent but instead conglomerate in-nature).

Indeed, I've watched field engineers when exploring the menu options and their
eyes light-up when they see that "Safe Mode" toggles ACPI off when enabled.
Extrapolating on their surprise, they appear to have an "Aha!"-moment as
previously... this field engineer had no idea what on God's green Earth what
"Safe Mode" did (or didn't) as he didn't know about "kenv" and certainly
couldn't read "Forth". At that point, he may not have had a full understanding
of all the options that Safe Mode  diddled, but at that point he at least knew
that Safe Mode is a multi-option that does many things -- which is more than
6.x, 7.x, or 8.x ever offered which simply boots immediately the Safe Mode
option is selected and does nothing to explain what it is that Safe Mode is
doing (which would in-turn properly calibrate the user's expectations).

Making the menu items completely independent would be take away the (however
slight) above value-add that was brought in by entwining these two menu-items.
I'm not saying that this would be a grave travesty, but would in-fact be a

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