linux-kernel - Re: should CONFIG_TMPFS_POSIX_ACL be so easily deselectable?

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Date:	Fri, 17 Jun 2011 17:28:15 -0700 (PDT)
From:	Hugh Dickins <hughd@...gle.com>
To:	"Robert P. J. Day" <rpjday@...shcourse.ca>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: should CONFIG_TMPFS_POSIX_ACL be so easily deselectable?

On Fri, 17 Jun 2011, Robert P. J. Day wrote:
> On Fri, 17 Jun 2011, Hugh Dickins wrote:
> > On Fri, 17 Jun 2011, Robert P. J. Day wrote:
> > >
> > > p.s.  i do notice a fairly recent change to that config file related
> > > to this:
> >
> > Yes, we were originally losing the oldconfig value of
> > TMPFS_POSIX_ACL.
> >
> > It would be easy to ack a patch from you which changes that wording
> > "If you don't know what Access Control Lists are, say N" to
> > something more informative about what the sound userspace wants.
> 
>   agreed -- something as simple as "if you don't know, say Y"?  :-)
> or would it be better to actually take a line or two to explain the
> consequences of that option?

I think both.  I've often thought "default N", "if unsure say Y"
Kconfig options contradictory, but I can see the point in this case.
Example or examples of the pain of saying N can be helpful.

> (by the way, this option affects more than just sound.)

Of course.

> 
> > It would be harder to justify having SOUND select TMPFS, or changing
> > the TMPFS_POSIX_ACL default to Y.  It's been N forever, and that is
> > how we prefer to add features.
> 
>   normally, i'd agree with you, except for the observation that, by
> far, the default config files across all architectures select that
> option.  there are 48 config files that select it, and only 3 that
> don't.  sometimes, that's a compelling argument that maybe it *should*
> be default yes.  but for now, i'll just whip up a more informative
> help sentence or two.

I don't think architecture defconfig files necessarily correlate with
Kconfig defaults.  You could argue that they should do so (so far as
arch-independent options are concerned), but I think the reality is
that arch defconfigs are produced separately, at the whim of various
people with different agendas.  I may be wrong (if unsure, say Y!).

> 
> rday
> 
> p.s.  as i mentioned, that option would appear to affect more than
> just sound.  as in:
> 
> $ getfacl /dev/kvm
> getfacl: Removing leading '/' from absolute path names
> # file: dev/kvm
> # owner: root
> # group: kvm
> user::rw-
> user:rpjday:rw-
> group::rw-
> mask::rw-
> other::---
> 
> so wouldn't KVM suddenly start behaving badly as well?

Dunno.  But certainly TMPFS_POSIX_ACLs are for whatever uses
tmpfs POSIX ACLs are being put to, not specific to sound - but
sound happens to be the case that wasted your time and Linus's.

Hugh
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