Re: Raspbian checks and question for Jessie
On Wed, Jun 05, 2013 at 09:38:43PM +0200, Axel Beckert wrote:
>Hi,
>
>peter green wrote:
>> As i've said before my understanding is that debian architecture
>> names represent a CPU family and ABI. Minium CPU requirements have
>> been changed both by derivatives (e.g. ubuntu i386 went first to
>> requiring "586" and then "686") and within debian (e.g. debian i386
>> went to requiring 486)
>>
>> Much as I do wish debian would improve support for variants with
>> adjusted minium CPU requirements (and I intend to make a suggestion
>> to the gcc maintainers about that, I just haven't got arround it it
>> yet) I don't think a new architecture name is the way to go.
>
>Lennart Sorensen wrote:
>> Well given arm6 binaries will install and work perfectly on official
>> armhf systems, making it a new architecture seems like a bad idea.
>>
>> That would be like saying i486 optimized packages should be a different
>> architecture than i686 optimized packages. There isn't really a good
>> reason to do that.
>
>So what would be the consequences of redefining armhf's minimum
>hardware requirements, i.e. would there a noticable performance loss
>on more modern systems if armhf would be built to include armv6 in the
>future?
There's two main points here.
There's the hardware differences between v6 and v7 (mainly support for
Thumb2 and NEON SIMD, VFPv2->VFPv3). As we have a sizeable chunk of
code which is currently targetted at v7 only, that would all need to
be rebuilt for v6 and we'd have to change the definitions in use for
compilers etc. Until that's all done, trying to run anything on v6 is
likely to fail in catastrophic ways.
Secondly, the v7-with-hard-float ABI is a standard that has been
agreed across the distros after lots of discussion and a fair amount
of in-fighting. If Debian unilaterally changed things on our side, we
would break any chance of binary compatiblity and I think that would
be a major mistake.
Basically, no - in my opinion we can't sensibly consider such a
change.
--
Steve McIntyre, Cambridge, UK. steve@einval.com
Into the distance, a ribbon of black
Stretched to the point of no turning back
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