Re: [gentoo-user] Upgrade + gcc dilemma

[Richard Fish]

On 1/8/06, Bob Sanders <rmsand@××××××××××.net> wrote:
> Simply put you can't.  The base system - emerge -e system, has to be done once and that
> gets everything in the system profile built with gcc 3.4.  However, both gcc and glibc need to
> be rebuilt again after the first pass, and anything using glibc needs to be rebuilt after glibc
> has been recompiled, thus the - emerge -e world.
>
> Think about it this way - things like binutils and linux-headers are used with gcc-3.4 and the old
> glibc to rebuild glibc.  But the new glibc is different than the old glibc, thus bin-utils is working
> with  pointers to places in glibc that may not exist any more.

This is false, you do not understand how shared libraries and the
dynamic linker work.  There is no advantage at all to rebuilding
everything due to a minor change in glibc versions, or even if you
rebuild glibc with a different version of the toolchain.

Gcc upgrades are bit more tricky, only because the ABI might change. 
Thus it is _sometimes_ necessary to carefully rebuild everything to
keep your system working.

For this gcc upgrade, rebuilding all of world or system is not
necessary.  It is only necessary to rebuild C++ applications and
libraries because the C++ ABI and libstdc++ library versions
havechanged.  You might _want_ to rebuild everything to take advantage
of any new optimizations that are available, but the revdep-rebuild
method is all that is needed to keep your system working.

So my suggested order for this would be:

# emerge -uav gcc
# gcc-config i686-pc-linux-gnu-3.4.4
# source /etc/profile
# emerge --oneshot -av libtool
# revdep-rebuild --library libstdc++.so.5
# emerge -Duv world

Watch out for a portage or python update though...and don't forget the
python-updater if there is a python update in there.

-Richard

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