On Wed, 1 Oct 2014, Rich Felker wrote:

> On Tue, Sep 30, 2014 at 10:52:22PM +0000, Joseph S. Myers wrote:
> > On Tue, 30 Sep 2014, Rich Felker wrote:
> > 
> > > > At least, it's good to have a confirmation that linking against
> > > > libgcc_eh is not the right solution. It confirms that the two stage gcc
> > > > build process we use in Buildroot is not at fault.
> > > 
> > > I'm skeptical of this. If the first gcc is built with
> > > --disable-shared, even plain libgcc.a (without the _eh, needed for
> > > certain math operations) is not suitable for inclusion into libc.so.
> > > The issue is that libgcc.a built this way does not have the right
> > > symbol visibility and creates ABI issues for any shared library it
> > > gets linked into. I can dig up an email thread link with more details
> > > if you're interested.
> > 
> > I fixed symbol visibility in --disable-shared libgcc over two years ago, 
> > and verified that (stripped) glibc built with such a --disable-shared GCC 
> > was byte-identical to the glibc you got after a further bootstrap stage of 
> > rebuilding GCC and glibc.
> 
> Good to know. Do you know what the first release was with this fixed?
> A lot of my experience is with people using pre-C++ or even pre-GPLv3
> versions so I'd like to be able to give them accurate information.

This was fixed (at least to the extent needed to get byte-identical glibc 
as described with glibc >= 2.17; there were also fixes in glibc 2.17 to 
support building with such a bootstrap GCC) in GCC 4.8 (with 
--with-glibc-version added in 4.9 to avoid needing to set 
gcc_cv_libc_provides_ssp=yes when configuring the first GCC on some 
architectures).

-- 
Joseph S. Myers
[email protected]
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