[Vm-dev] Re: [squeak-dev] A update to SystemTracer for getting back to 32 bits

[Eliot Miranda]

Hi David,

On Thu, Jan 15, 2015 at 7:43 PM, David T. Lewis <lewis at mail.msen.com> wrote:

>
> On Mon, Jan 12, 2015 at 04:52:32PM +0100, Bert Freudenberg wrote:
> > On 12.01.2015, at 01:47, David T. Lewis <lewis at mail.msen.com> wrote:
> > >
> > > I made a minor update to the SystemTracer that allows it to convert a
> 64-bit
> > > image back to 32-bit format, and it worked perfectly with my working
> Squeak
> > > image that has been in 64-bit format for several months now.
> >
> > Nice!
> >
> > >  The resulting 32-bit image must be opened first using an interpreter
> VM,
> > >  after which it can be run normally with a Cog VM. Tracing should be
> done
> > >  using an interpreter VM.
> >
> > Why is that?
> >
> > - Bert -
> >
>
> The issue was Float word ordering differences in Cog/StackInterpreter. I
> made
> an update to SystemTracer that mostly handles this, the main benefit being
> that Cog can now be used to execute a much faster system trace from 32-bit
> image to 64-bit 68002 (or the mythical 68003) image, non-Spur:
>
>   Name: SystemTracing-dtl.27
>   Time: 15 January 2015, 10:20:22.019 pm
>
>   Allow 32-bit images to be traced to 64-bit using 32-bit Cog VM. Handle
> float
>   word ordering differences between StackInterpreter and Interpreter.
> Produces
>   a runnable 68003 image, 64-bit object format, closures, and Cog float
> word
>   ordering. Requires package ImageFormat from VMMaker repository, else
> error
>   is raised indicating how to hard code a workaround. This seems a
> reasonable
>   dependency given the increasing number of image formats in circulation.
>
>   Trace from 64-bit image to 32-bit still requires an initial load and save
>   using an interpreter VM prior to running with Cog, reason unknown.
>
> Dave
>

Great!
-- 
best,
Eliot
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