Date: Wed, 31 Jan 1996 22:18:35 -0800 From: John Polstra <jdp@polstra.com> To: nate@sri.MT.net Cc: CVS-committers@freebsd.org, cvs-lib@freebsd.org Subject: Re: cvs commit: src/lib/csu/i386 crt0.c Message-ID: <199602010618.WAA13878@austin.polstra.com> In-Reply-To: <199601301628.JAA11970@rocky.sri.MT.net>
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Nate wrote:
> > > Back out the thread_init code in order to allow -current to bootstrap
> > > from -stable, until a better solution is found.
> >
> > Umm, I think this is a bit drastic! Bootstrapping is a problem we have to
> > deal with now and again in -current and it shouldn't be a barrier to new
> > development.
>
> Agreed, but as has been hashed out, there is no way of bootstrapping
> right now inside the Makefiles. You can't do it automatically due to
> races, so until a Real (tm) solution is found where folks can
> automatically bootstrap, this is the temporary solution.
I was studying my logs from a recent make world, and also the top-level
Makefile. I was looking for something else, but in the process I came
to understand the cause of the thread_init-crt0-libc bootstrapping
problem. I think it could be solved in the top-level Makefile without
too much trouble.
The problem is in this section of code under the "libraries:" target
(note: crt0 is in lib/csu/i386):
.if exists(lib)
cd ${.CURDIR}/lib/csu/i386 && \
${MAKE} depend all install ${CLEANDIR} ${OBJDIR}
cd ${.CURDIR}/lib && \
${MAKE} depend all install ${CLEANDIR} ${OBJDIR}
.endif
The first command does this:
depend in lib/csu/i386
build in lib/csu/i386
install from lib/csu/i386
Then, the second command does this:
depend in lib/csu/i386
depend in lib/libc
depend in lib/libcompat
depend in lib/libcom_err
... the same for many more subdirectories of lib
depend in lib/msun
build in lib/csu/i386
build in lib/libc
build in lib/libcompat
build in lib/libcom_err
... the same for many more subdirectories of lib
build in lib/msun
install from lib/csu/i386
install from lib/libc
install from lib/libcompat
install from lib/libcom_err
... the same for many more subdirectories of lib
install from lib/msun
The problem is that the new crt0.o gets installed loooooong before
the new libc gets installed -- but really, they need to be installed
at almost the same time. Between the time that crt0.o is installed
and libc is installed, much work is put into building the libraries
in the other subdirectories of lib. For some of them (e.g.,
libmytinfo, where the bootstrapping problem first shows up), the
build process involves compiling some programs and executing them.
Those programs get linked with the new crt0.o (because it's already
installed) but with the old libc. That's why the undefined symbol
error is occurring.
I think this particular problem could be solved quite simply, by just
deleting the first command from the top-level Makefile:
cd ${.CURDIR}/lib/csu/i386 && \
${MAKE} depend all install ${CLEANDIR} ${OBJDIR}
That would defer the installation of crt0.o until immediately before the
installation of libc. I _believe_ there would be no negative
side-effects from this change.
Unfortunately, I can't test my proposed fix at the moment. But maybe
this explanation will help Julian or somebody else who's working on it.
If you all already knew about this, just ignore me. But I've seen
some misleading stuff go by on the mailing list, referring to
mysterious hidden dependencies from the makedepend step, and that's
just wrong. The actual explanation is much simpler.
--
John Polstra jdp@polstra.com
John D. Polstra & Co., Inc. Seattle, Washington USA
"Self-knowledge is always bad news." -- John Barth
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