Re: [gentoo-user] Migration from single to dual core

[Florian Philipp]

On Thu, 2008-01-03 at 00:14 +1000, Alan E. Davis wrote:
> I have been running a machine for a long while.  I am beginning to
> think that the old saw that Gentoo isn't release oriented is hogwash:
> each installation seems to be more polished, leaving behind a windrove
> of cruft accumlating over the years.  The few times I have installed
> since my introduction two years ago have each exposed some more
> polished installation aspects/details.
>
> Be that as it may, I have now installed a new motherboard and CPU.  I
> have moved from a 64 bit AMD single core Athlon 64 to a  dual core AMD
> Athlon 64.  The install has gone well, I have had to recompile the
> kernel before migrating; however, some questions remain.
>
> So it's back to the old threads about whether 64 bits is superior to
> 32, etc.  My question now is, given that the system is working damned
> well now, what is the best way to handle this: recompile everything?
> Should I recompile gcc and the libraries and all compilers.
>
> I have to say that this system is pretty solid, but it's been hard to
> keep up with the housekeeping.  And emerge -uDav world has been next
> to impossible.
>
> So, again, what differences will there be, that will require immediate
> adjustment?  I have changed to "-j3" in make.conf.  I have so many
> packages installed it will take many days to recompile, and, again, I
> am considering a reinstallation of everything.  Gentoo has cured me of
> that weakness for constant upgrades and installs, even while
> convincing me of the excellence of compiling for the machine.

I don't think you have to recompile everything. AMD64 and AMD64 X2 share
the same -march setting. All that might need to be done is adding -msse3
to your CFLAGS, because the first generations of AMD64 didn't have that
feature and thus it's not included in -march=k8.

However, this flag should only influence multimedia apps and encoders
like mplayer, vlc or ogmtools (and their direct deps).