[Vm-dev] Re: [squeak-dev] What is the upper memory limits of Cog?

[David T. Lewis]

On Thu, Sep 25, 2014 at 11:28:04PM -0500, Chris Muller wrote:
> 
> I have had to put memory-checking into my code and terminate "stale"
> resources when it hits the ceiling.  Part of my memory-checking logic
> relies on (Smalltalk vmParameterAt: 3) to estimate available memory,
> but since it is returning -868260916 (that's right, --negative--) for
> that value, my assumptions that it would always be positive were wrong
> and that explains why the memory-checking is not working correctly.
> 
> Is something possibly wrong that this is negative?  Am I supposed to
> take the absolute value of it?

It's probably a VM buglet, an unsigned address is being returned as a signed integer.

To illustrate, load package TwosComplement from SqueakMap, then:

  -868260916 asRegister asUnsignedInteger ==> 3426706380

Dave