Re: Preparing to release 0.9.12

[Rich Felker <dalias@aerifal.cx>]

On Thu, Jul 25, 2013 at 01:18:06PM -0400, Rich Felker wrote:
> I should add some documentation on this on the wiki. Defining what is
> part of "the ABI" is tricky. For example, you could say code built for
> armv5 is a different ABI from code built for armv4, since it's using
> instructions that aren't available on armv4. However, the key reason I
> don't consider those "different ABIs" is that, as long as the cpu
> you're running on supports all the instructions used in the main
> program and all libraries, you can use a mix of armv4 and armv5 built
> modules with no restrictions.
> [...]
> Basically, configurations A and B are different archs or subarchs if
> you can't link code built with configuration A to code built with
> configuration B.

For what it's worth, this agrees with the outcome of Debian's
discussion on adding the armhf port:

    The eventual conclusion was that port names in Debian should
    encode incompatible ABIs, not compatible variations within an ABI
    (such as CPU optimisations, referred to as 'flavours'). The
    default flavour for a port can change over time as older CPUs
    become obsolete. (e.g. the i386 architecture has been built for
    386, 486 and 586 flavours over time). Rebuilds of a port for a new
    flavour within the ABI are possible to gain performance
    improvements, but Debian itself normally provides builds to the
    lowest common denominator still in widespread use, maximising
    generality. Thus attempts to encode all the possible flavour
    options in the port name were unnecessary and produced long and
    awkward names. A better solution to the problem of recording the
    flavour to which a port or package is built is suitable package
    metadata.

Source: http://wiki.debian.org/ArmHardFloatPort

Rich