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Date: Fri, 6 Nov 2009 02:16:45 +0000
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] [PATCH 0/4] net-bridge: rootless bridge support for
	qemu
Message-ID: <20091106021645.GK21630@shareable.org>
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To: Avi Kivity <avi@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, Arnd Bergmann <arndbergmann@googlemail.com>, Scott Tsai <scottt.tw@gmail.com>, Dustin Kirkland <kirkland@canonical.com>, Juan Quintela <quintela@redhat.com>, qemu-devel@nongnu.org, Michael Tsirkin <mst@redhat.com>

Avi Kivity wrote:
> On 11/05/2009 07:16 PM, Scott Tsai wrote:
> >On Fri, Nov 6, 2009 at 12:50 AM, Anthony Liguori<aliguori@us.ibm.com>  
> >wrote:
> >   
> >>It's just a bit annoying to create an entire new
> >>project for a few hundred line helper.
> >>     
> >This new project would also be a better place for 'tunctl' and other
> >projects such as user mode linux might want to use your new helper
> >program.
> >   
> 
> Seems like a library implemented as executables instead of a shared object.

Yes.  It's an executable because it needs setuid to do privileged things...

It could be provided as a shared object (which calls an executable if
it needs setuiding), but then for some things you'd have to provide an
option like -net helper=/path/to/my/helper.so, and you might not want
the implied fixed ABI, and it'd be harder to use scripts.

After all we don't have -net
script=/path/to/my/upscript.so,downscript=/path/to/my/downscript.so do
we? ;-)

Spawning an executable is really fast in Linux.  For something which
is only called a few times at most when the program starts or is
rarely reconfigured, I don't see any reason not to call an executable.

-- Jamie