[squeak-dev] Backward image and VM compatibility

David T. Lewis lewis at mail.msen.com
Tue Jan 10 14:13:30 UTC 2017

On Tue, Jan 10, 2017 at 11:59:18AM +0100, Bert Freudenberg wrote:
> On Sat, Jan 7, 2017 at 12:58 AM, David T. Lewis <lewis at mail.msen.com> wrote:
> >
> > I confirm your high pitch symptoms for Squeak 1.13u on SqueakJS, but I am
> > not
> > able to test 1.13u on the interpreter VM. It runs and browsers work, but I
> > cannot evaluate an expression in a workspace. This seems to be the case for
> > images earlier than Squeak 1.31 so something is still broken for the
> > interpreter
> > VM for Squeak 1.23 and earlier. The issue seems to be related to something
> > that
> > changed between Squeak 1.23 and Squeak 1.31.
> >
> > Sound issues aside, if you want to do any serious work on a Squeak 1.13u
> > image
> > I still recommend using SqueakJS :-)
> >
> Some of the early images are missing UnixFileDirectory so SqueakJS has a
> mode for emulating Mac file names:
> https://github.com/bertfreudenberg/SqueakJS/search?q=emulateMac
> But "1.13u" should be one of Ian's images which include this class so I'm
> not so sure what changed between that and 1.31 ...

Thanks Bert. It appears to be something related to MethodContext. Since it
is VM related, I initially guessed that it might be something related to
the method cache, but I was able to disable that in the VM and the symptoms
did not change. I'm thinking now that it might be a failure in primitive 61
when trying to copy a MethodContext, this based on the debugger stack
(although I cannot actually display anything useful in the debugger).

I'll report back if I end up figuring it out, meanwhile any and all historical
clues are appreciated :-)


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