[squeak-dev] 64 bit migration

Bert Freudenberg bert at freudenbergs.de
Fri Oct 18 00:30:58 UTC 2019


On Thu, Oct 17, 2019 at 5:19 PM Bert Freudenberg <bert at freudenbergs.de>
wrote:

> On Thu, Oct 17, 2019 at 5:10 PM tim Rowledge <tim at rowledge.org> wrote:
>
>>
>> > On 2019-10-17, at 4:19 PM, Eliot Miranda <eliot.miranda at gmail.com>
>> wrote:
>> >
>> > But I still think that the right way is to export one's code as
>> packages and rebuild.  Most code "just works", but nothing is going to
>> automagically replace one's use of someObject/nextObject, or the assumption
>> that Float is the only float class, so the user is still going to have to
>> test their code carefully.
>>
>> Extra hassles come from images where a great deal of setup was done and
>> is not necessarily encoded in, err, code... and of course a lot of these
>> older images are using older code for some important parts. Updating them
>> can easily be a barrier too far.
>>
>> A VM capable of running a 32bit image is clearly possible. One might
>> consider simplifying the problem a little by asserting that since 32bit
>> Spur images are easy to convert there is no need to worry about handling
>> them with this VM. That also removes the need to deal with the clevernesses
>> added since the advent of the Spur images, which should simplify things a
>> tad. To be honest, it's probably best to just run a plain(ish) interpreter
>> VM (perhaps the stackvm enhancements would be smart to use) and accept that
>> such old images will just be a bit slow by comparison.
>>
>> We already have VMs with most of these attributes so with luck the
>> remaining work is, surely,  mostly making sure that 32 bit values do not
>> get incorrectly promoted.
>>
>> tim
>>
>
> Those VMs do not work anymore because OS vendors (particularly Apple) like
> to deprecate and then disable old APIs. So the VM needs to be updated to
> keep on top of that.
>
> The easiest might be to take a current VM and replace its object engine
> with an old interpreter.
>
> - Bert -
>

Btw, this discussion should go to vm-dev, see John's thread there.

- Bert -
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