Use of --enable-threads=posix in chapter 5

Greg Schafer gschafer at zip.com.au
Sat Sep 14 18:20:02 PDT 2002


On Sat, Sep 14, 2002 at 09:51:58AM -0700, Jesse Tie-Ten-Quee wrote:
> Yo,
> 
> On Sat, Sep 14, 2002 at 05:11:43PM +0100, Mark Hymers wrote:
> > Ah.  In that case the only thing I can say is: Greg? :-)
> 
> http://linuxfromscratch.org/view/cvs/chapter05/gcc.html
> 
> "--enable-threads=posix: This enables C++ exception handling for
> multithreaded code."
> 
> Greg feel free to elaborate, but that kinda spells it out for me, so ;)

Yep. I believe Zack is correct. It's prolly a leftover from when we were
building C and C++ in Ch 5.

I just did some extensive grepping and feel certain that it could be
dropped from Ch 5.  The only concern is that there is one makefile
variable (GCC_THREAD_FILE) in the main gcc dir that gets set, but it
appears to be unused.  I hear you asking "what if the GCC guys decide
to use it in the future?". Well sure, its possible, but it looks to me
as if it was phased out and is a leftover in the gcc sources..

As an aside, I see on the C++ ABI page:-

http://gcc.gnu.org/gcc-3.2/c++-abi.html

that    --enable-threads=posix   is supposed to be selected by default.
In other words, one doesn't need to specify it on the command line as
configure will select the right one by default. I was dubious about this
and did some testing a while back. My testing was inconclusive but I was
fairly certain that --enable-threads=posix WAS required.

Now that I've revisited the issue, I see this in the changlog that went in
between gcc-3.1.1 and gcc-3.2 ie: after I first looked at it:-

2002-08-06  Jakub Jelinek  <jakub at redhat.com>

        * config.gcc (*-*-linux*): Default to --enable-threads=posix if no
        --{enable,disable}-threads is given to configure.
        (alpha*-*-linux*, hppa*-*-linux*, i[34567]86-*-linux*,
        x86_64-*-linux*, ia64*-*-linux*, m68k-*-linux*, mips*-*-linux*,
        powerpc-*-linux-gnualtivec*, powerpc-*-linux*, s390-*-linux*,
        s390x-*-linux*, sh-*-linux*, sparc-*-linux*, sparc64-*-linux*):
        Remove thread_file setting here.

So in theory, we could drop --enable-threads=posix from Ch 6 as well.

NOTE - I haven't tested it yet, just putting it on the record. Safer to
leave it in for now.

Greg
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