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Date: Tue, 14 Jan 2014 11:21:19 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v15 6/9] module: implement module loading
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Michael Tokarev <mjt@tls.msk.ru>, QEMU Developers <qemu-devel@nongnu.org>, Alex Bligh <alex@alex.org.uk>, Paolo Bonzini <pbonzini@redhat.com>, Miroslav Rezanina <mrezanin@redhat.com>, =?iso-8859-1?Q?Llu=EDs?= Vilanova <vilanova@ac.upc.edu>, Richard Henderson <rth@twiddle.net>

On Mon, 01/13 22:05, Peter Maydell wrote:
> On 13 January 2014 16:59, Paolo Bonzini <pbonzini@redhat.com> wrote:
> > From: Fam Zheng <famz@redhat.com>
> >
> > This patch adds loading, stamp checking and initialization of modules.
> >
> > The init function of dynamic module is no longer directly called as
> > __attribute__((constructor)) in static linked version, it is called
> > only after passed the checking of presense of stamp symbol:
> >
> >     qemu_stamp_$(date +%s$$$RANDOM)
> >
> 
> > +echo "CONFIG_STAMP=`date +%s`_$$_$RANDOM" >> $config_host_mak
> 
> This is not really a good idea because $RANDOM is a bashism
> and our configure script is a generic POSIX shell script. In
> particular if you configure on Ubuntu you're likely to find that /bin/sh
> is dash and $RANDOM silently expands to the empty string.
> 
> (One day I will clean up the tempfile generation stuff to fix
> its misuse of $RANDOM...)
> 

So what's the best way to generate random number here?

> > +void DSO_STAMP_FUN(void);
> > +/* For error message, this function is an identification of qemu module */
> 
> What is this comment trying to say?

Existence of this symbol indicates it *is* a qemu module. Where we continue to
check for existence of DSO_STAMP_FUN, and report it's only the wrong version.

Thanks,
Fam