Date: Thu, 1 Apr 2004 14:39:08 -0800
From: Joe Buck <Joe.Buck@synopsys.COM>
To: Andi Kleen <ak@suse.de>,
       Ulrich Weigand <weigand@i1.informatik.uni-erlangen.de>, gcc@gcc.gnu.org,
       linux-kernel@vger.kernel.org, schwidefsky@de.ibm.com
Subject: Re: Linux 2.6 nanosecond time stamp weirdness breaks GCC build
Message-ID: <20040401143908.B4619@synopsys.com>
References: <200404011928.VAA23657@faui1d.informatik.uni-erlangen.de> <20040401220957.5f4f9ad2.ak@suse.de> <20040401203923.GA32177@nevyn.them.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.2.5.1i
In-Reply-To: <20040401203923.GA32177@nevyn.them.org>; from dan@debian.org on Thu, Apr 01, 2004 at 03:39:23PM -0500
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 827
Lines: 20

[ Linux 2.6 losing the nanoseconds from a file timestamp ]

There are two different failure modes, but in most cases only one
results in a real problem.

Case 1: make falsely thinks that the .o is younger than the .c.  It
decides not to rebuild the .o, resulting in a bad build.

Case 2: make falsely thinks that the .c is younger than the .o.  It
recompiles the .c file, even though it didn't have to.  Harmless.

So if we can make the bad situation look like a tie, and always rebuild
in the case of a tie, we will obtain valid builds, sometimes with
an extra compilation or two.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/