RE: revisiting tunables under Safe Mode menu option

> -----Original Message-----
> From: Julian Elischer [mailto:julian_at_freebsd.org]
> Sent: Thursday, March 01, 2012 1:52 PM
> To: Devin Teske
> Cc: 'Andriy Gapon'; freebsd-current_at_freebsd.org; 'Devin Teske'; 'John Baldwin'
> Subject: Re: revisiting tunables under Safe Mode menu option
> 
> On 3/1/12 1:35 PM, Devin Teske wrote:
> > Right, making the assumption that FreeBSD's safe mode will do the same thing
> as
> > Windows' safe mode is a poor assumption.
> >
> > As you point out, all those things that Windows safe mode does, FreeBSD does
> > not.
> >
> > X11 drivers are not affected by safe mode.
> >
> > Network is not affected by safe mode.
> >
> > Services started at boot, are not affected...
> >
> > So I would welcome discussions involving development of something better
> (and am
> > willing to help).
> 
> but, with help from the rc people. it could..
> the kenv framework gives us a much more flexible way to implement the
> sysV runlevels that linux inherrited.
> 
> here's what I would envision:
> 
> a single safe mode switch
> a way to control what that does (either 'safe mode' drops you to
> another menu which includes
> "boot safe mode:" and "configure safe mode" (the second one drops you
> to yet another menu of check boxes).
> 
> the result of this is a preconfigured set of kenv entries being dumped
> into the kenv space.
> 
> The rc system can look at the kenv space for some key entries and act
> accordingly.
> it can also SAVE to /boot/safe_mode.conf the set of kenv entries
> selected when safe mode is used,
> and the forth code can load that and use it as a default on next
> 'safe' mode usage.
> 
> 
> BTW do we use the forth boot stuff on all architectures?
> what of NFS boots?

Glad you asked.

There are architectures that don't use beastie.4th at all and thus simply fall
to the autoboot sequence after handling loader.conf.

These architectures lack a menu, so it would be nice if we accommodated them
with (at least) allowing manual configuration through environment variables
(later grabbed with kenv by the rc folks).

I don't think it's beyond scope to think we couldn't cleanly implement this with
(say) a well-crafted /etc/rc.d/safemode

Not exactly sure what "service safemode start" should do (BSD doesn't have the
same concept of runlevels as Linux does; so it's not exactly intuitive to think
we could go from multi-user mode *into* safe mode).

But "service safemode status" would be interesting.

Interestingly, it would perhaps be nice if "service safemode stop" brought the
system back to fully usable without need for reboot (something Windows doesn't
offer).
-- 
Devin


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