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Re: (toplevel) introduce host subdir configuration in Makefile
- From: Thomas Dickey <dickey at herndon4 dot his dot com>
- To: Alexandre Oliva <aoliva at redhat dot com>
- Cc: Daniel Jacobowitz <drow at mvista dot com>, Nathanael Nerode <neroden at twcny dot rr dot com>, gcc-patches at gcc dot gnu dot org, gdb-patches at sources dot redhat dot com, binutils at sources dot redhat dot com, dj at redhat dot com, autoconf at gnu dot org
- Date: Mon, 2 Dec 2002 17:06:37 -0500
- Subject: Re: (toplevel) introduce host subdir configuration in Makefile
- References: <20021128221312.GA20889@doctormoo> <20021202161822.GA11078@nevyn.them.org> <oru1hwml2i.fsf@free.redhat.lsd.ic.unicamp.br>
- Reply-to: dickey at herndon4 dot his dot com
On Mon, Dec 02, 2002 at 02:39:49PM -0200, Alexandre Oliva wrote:
> On Dec 2, 2002, Daniel Jacobowitz <drow@mvista.com> wrote:
>
> > You may already know this, but just to be careful I'll mention it
> > anyway... it is not necessarily safe to configure more than one
> > subdirectory at a time. One possibly gotcha is the updating of
> > $cache_file. It isn't done atomically and so if you happen to have two
> > subdirectories with the same (essentially) configure.in, and they
> > happen to get started on an SMP system by make -j2 at (essentially) the
> > same time, you can blow out the cache file.
>
> > This isn't entirely hypothetical. A similar thing happened in
> > libiberty with two invocations of config.status.
>
> This was a bug in autoconf 2.13, that's fixed in autoconf 2.5x.
arguable (as usual). 2.13 didn't pretend to support parallel make.
2.5x pretends to, but (as you note) config.cache isn't handled.
So it appears more as a bug in 2.5x
--
Thomas E. Dickey <dickey@invisible-island.net>
http://invisible-island.net
ftp://invisible-island.net