linux-kernel - Re: [PATCH 05/10] drivers/char: Support compiling out /dev/zero

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Date:	Wed, 28 Jan 2015 22:52:25 +0100
From:	Pavel Machek <pavel@....cz>
To:	josh@...htriplett.org
Cc:	Tom Zanussi <tom.zanussi@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/10] drivers/char: Support compiling out /dev/zero

On Wed 2015-01-28 13:51:06, josh@...htriplett.org wrote:
> On Wed, Jan 28, 2015 at 10:07:51PM +0100, Pavel Machek wrote:
> > On Fri 2015-01-23 12:37:11, Tom Zanussi wrote:
> > > Some embedded systems with tightly controlled userspace have no use
> > > for /dev/zero, and could benefit from the size savings gained by
> > > omitting it.  Add a new EMBEDDED config option to disable it.
> > > 
> > > bloat-o-meter (based on tinyconfig):
> > > 
> > > add/remove: 0/3 grow/shrink: 0/1 up/down: 0/-391 (-391)
> > > function                                     old     new   delta
> > > chr_dev_init                                 162     147     -15
> > > mmap_zero                                     16       -     -16
> > > zero_fops                                    116       -    -116
> > > zero_bdi                                     244       -    -244
> > > 
> > > Signed-off-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
> > 
> > I'm not sure that 400 bytes are worth additional Kconfig noise. .. and
> > pretty much everyone needs /dev/zero...
> 
> Relatively few, actually, given MMAP_ANONYMOUS.  Memory isn't allocated
> via an mmap of /dev/zero.  It's useful for systems with shells that want
> to redirect from it or read from it, but less useful for environments
> with entirely compiled code.
> 
> /dev/null is much more commonly needed, though there are still systems
> that won't need it (and can just disable read/writes on an fd entirely
> rather than duping /dev/null to that fd).
> 
> That said, I'd be entirely in favor of consolidating many of these
> "miscellaneous character device" options into a couple of Kconfig
> options.  It doesn't seem critical to *individually* control each of
> these files in /dev.

Yes, grouping it would make it more acceptable.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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