Date: Mon, 13 Oct 2014 19:40:14 -0700 From: Tim Kientzle <tim@kientzle.com> To: Matthias Apitz <guru@unixarea.de> Cc: freebsd-hackers@freebsd.org Subject: Re: gmake && file time precision of 1 second Message-ID: <E930C1E7-E5C9-42C4-A9C4-D30281607370@kientzle.com> In-Reply-To: <20141013092018.GA2737@unixarea.DDR.dd> References: <20141013092018.GA2737@unixarea.DDR.dd>
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On Oct 13, 2014, at 2:20 AM, Matthias Apitz <guru@unixarea.de> wrote: > > Hello, > > I have a large project where a shell script fires up > gmake runs in subdirs as: > > for dir in src norm print ....; do > cd $dir > gmake > cd .. > done > > in each subdir *.c are compiled to *.o and the resulting *.o are ar'ed > into all the same lib.a; based on normal Makefile rules like: > > SRCS = f1.c f2.c > OBJS = $(SRCS:.c=.o) > > .c.o: > $(CC) -c ... $*.c > > lib.a:: $(OBJS) > $(AR) $@ $(OBJS) > > > after moving to a faster server it turned out that gmake sometimes forget > to ar the *.o into the lib; I investigated it and it turned out that the > *.o files have the same modification time (in seconds) as the target > lib.a (which was produced/updated in the last directory worked on) and > gmake thinks that the lib.a is uptodate. > > Any idea how to address this in the Makefiles? Instead of updating the same lib.a from every makefile, instead consider creating a separate lib.a in each directory and then combining them at the end. Combining .a libraries is a little tricky: Try creating a dir, extracting each lib.a into that same directory, then creating a new lib.a. It might be possible to combine them directly using tar —format=ar but I’ve not tried it. Cheers, Tim
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