[squeak-dev] [Vm-dev] Apple starting to alert users that it will end 32-bit app support on the Mac

Clément Bera bera.clement at gmail.com
Thu Apr 12 15:29:06 UTC 2018


Hi all,

question inlined...

On Thu, Apr 12, 2018 at 4:05 PM, Eliot Miranda <eliot.miranda at gmail.com>
wrote:

>
> Hi Bert,
>
>
> On Apr 12, 2018, at 6:03 AM, Bert Freudenberg <bert at freudenbergs.de>
> wrote:
>
> If that's indeed the case we need to make a 64 bit VM for 32 bit images. I
> think this should be just a matter of picking the right compiler options.
>
>
> How so?  AFAIA it is not.  It means, for example, changing every memory
> access for an instance variable from 64 to 32 bits.  It is non-trivial.
>
> What /is/ trivial is detecting that an image's word size is unsupported on
> a platform and offering to convert it, a process that takes less than a
> minute for typical images.
>

Why does this process take a full minute ? Could we do that in 1 second ?
Is it only because of SmallFloat ?

I mean I could dream of a world where 64-bits image under 2Gb are saved as
32 bits images to be more compact on disk. Then at start-up, the 32 bits
image is converted into a 64 bits image if started on a 64 bits VM, or not
if started on a 32 bits VM. We could also save image under 65k as 16 bits
images, and convert them back as start-up :-). Obviously that would work
only if the conversion is fast, but I think it could be with tricks to
handle SmallFloats.

Note that the code optimized by Sista is currently dependent on word size
though due to overflow computation, but I guess we'll solve this problem
later.



>
> If we go this route we would include a headless 64-bit image that converts
> 32-bit images to 64-bits on 64-bit only systems, and a headless 32-bit
> image that converts 64-bit images to 32-bits on 32-bit only systems.
>
> IIRC 64 to 32 bit conversion needs to be written, but I think it is
> trivial compared to building a 64-bit vm for 32-bit images.
>
> Of course this applies only to Spur images.  We don't have a way of
> automatically converting V3 images to Spur.  Yo do that going forward we
> may have to depend on OS virtual machines, but somehow I can't see an ARMv8
> Mac supporting x86 VMs like Parallels.  This could be the end of an
> interoperability era.
>
>
> Otherwise we won't have any way of opening regular 32 bit images on Macs.
>
> - Bert -
>
> On 12 April 2018 at 14:47, Fabio Niephaus <lists at fniephaus.com> wrote:
>
>> Hi all,
>>
>> According to [1], Apple has started to alert users when they open a
>> 32-bit app on the Mac and I've seen such a dialog today myself when opening
>> a 32-bit Squeak image.
>>
>> It looks like it is time to make 64-bit the default, maybe with the next
>> release? The Pharo community is already doing that for quite some time, so
>> I'm wondering if there is any reason not to do the same?
>>
>> Best,
>> Fabio
>>
>> [1] https://techcrunch.com/2018/04/11/apple-starting-to-alert-us
>> ers-that-it-will-end-32-bit-app-support/
>>
>>
>>
>>
>
>
>


-- 
Clément Béra
https://clementbera.github.io/
https://clementbera.wordpress.com/
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