Re: Current and upcoming toolchain changes for jessie
+++ Matthias Klose [2013-05-07 15:25 +0200]:
> == GCC 4.8 ==
>
> GCC versions were updated to GCC 4.7.4 and GCC 4.8.0 (both updated to
> the current branch). The default compilers were not yet changed in
> unstable. It is planned to make GCC 4.8 the default on the x86
> architectures after the 4.8.1 release (expected later this month), and
> after 4.8 does migrate to testing. Suggesting that boost transitions
> from 1.49 to 1.5x at about the same time.
>
> The decision when to make GCC 4.8 the default for other architectures
> is left to the Debian port maintainers.
>
> It is planned to only keep GCC 4.8 and the upcoming GCC 4.9, and to
> remove 4.4, 4.6 and 4.7 from jessie.
In general I think moving to gcc 4.8 is a good thing for the arm
ports. New development and support appears there, and if we want to
get rid of 4.7 (and 4.4 and 4.6) for jessie then the earlier we start
the earlier it'll all be fixed.
4.8 is particularly useful for arm64, which I hope/expect to be in a
releasable state by jessie, 4.8 is the first upstream release with
official support (although in practice it's pretty good in the linaro
branch of 4.7 (which is the branch we are using for that arch)).
What I'm a bit vague about is what actual advantages we get beyond
general optimisations, and what breaks. Vectorisation support is much
improved in 4.8, but that's not used by default builds SFAIK, due to
neon being optional.
Cross-toolchain builds no doubt need some fixing up for 4.8 (I've only
done them for 4.7), but that's work that needs doing anyway.
So unless anyone can think of good reasons for sticking with 4.7 a bit
longer, I'm inclined to say change the default along with x86, but
defer to toolchain experts if they disagree.
> == binutils ==
>
> binutils 2.23.2 will be uploaded to unstable after GCC 4.8 as the
> default on x86 reaches testing. Later updates will introduce binutils
> trunk leading to 2.24, later this year.
I've only tested 2.23.1 but had no trouble at all there. I'd expect
2.23.2 to be fine too.
Wookey
--
Principal hats: Linaro, Emdebian, Wookware, Balloonboard, ARM
http://wookware.org/
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