subarch support
On Tue, Jul 13, 2010, Riku Voipio wrote:
> If dpkg had subarchitecture support, lpia wouldn't have been as big
> a issue. Ubuntu decided to shortcut and not add support for compatible
> subarchs in dpkg, and the result was what it always is when people make
> shortcuts...
>
> Subarchs could also be useful if we wanted to build softfp abi compatible
> armv6/armv7 armel builds of the whole debian repository. Of course we could do
> builds without subarchs, but then users would be unable distinguish which
> installed packages are for which cpu, and providing that via debian infra
> would not be possible.
It sounds like you have good ideas about the subarch concept; would you
mind expanding on them a bit?
Whenever I think of subarch, I either found relatively low benefits, or
a lot of added complexity. I tried bringing it up at last UDS during a
session where we had some kind of brainstorm of which dpkg features
would be useful for the future, especially ARM related ones, and
instead of subarch we came with the concept of "capabilities". I
apologize for the lack of wiki page summarizing the discussion, the raw
notes are in the Capabilities paragraph at:
http://people.canonical.com/~lool/dmart-uds-m-notes/arm-m-dpkg-wishlist.txt
(read the bottom too for some fun :-)
I think the Cpu/Endianness/Capabilities concepts are mostly
anti-shoot-yourself-in-the-foot measures. I could imagine APT helping
a bit more than dpkg here though.
I'd love hearing your thought on subarch! Notably, whether we have
them in dependencies, whether we flag .debs as "is incompatible with
systems which don't have this feature" or "is an improvement for
systems which have this feature", whether we have subarch for SoCs, for
optimizations levels, both etc.
> LPIA was mainly a issue since people used it as "if arch=lpia then build
> mobile ui". That prevented users from installing full versions of software
> or trying mobile UI's in regular i386 installations.
(This was largely fixed afterwards though; it was only used for the
first or first two lpia releases, and was indeed very crackful.)
I personally found it challenging to request inclusion of the lpia arch
in Debian packages when I had to explain that the arch was only used by
Ubuntu.
--
Loïc Minier
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