On 16/12/19 3:44 AM, Eliot Miranda wrote:
> +1.  But that's a fair amount of work ;-)  These flags are a precious 
> resource.  What I was suggesting below was that the legacy code, 
> protected by ifdef's, was enabled, and stayed there until some major 
> release, at which time it could be disabled.  I agree with you that 
> disabling it by default is wrong.
> 
> IOn general with the VM one wants to maintain backward compatibility 
> until a major release arrives that makes it impossible to for the 
> current VM to support some set of older versions.  For example, the Spur 
> VMs we use now cannot run V3 images.  So when Spur VMs were introduced 
> any backward compatibility for pre-Spur images could be jettisoned from 
> the Spur VMs.

A third option is to separate image loading from interpreter. The 
top-level executable will be the image loader. It will load and 
interpret the header, determine the variant and then spawn a 
variant-specific interpreter with appropriate arguments to interpret the 
image. So we just ship one loader (say squeakvm) and one or more 
interpreters (squeak-trunk, squeak-cog, squeak-spur32, squeak-spur64 etc).

Regards .. Subbu