[Vm-dev] I think I've found a bug in the 64-bit Squeak VM memory compactor

[ungar at mac.com]

Jecel,

Great story! Creative fix. Just to clarify, I am talking about the part of the image AFTER the header; where the oops start.

Thanks for the smile,

- David


On Jun 14, 2010, at 6:05 PM, Jecel Assumpcao Jr. wrote:

> 
> Dave,
> 
>> The workaround for my VM is simply to skip those first free words, so that the
>> first word in the heap is a non-free object. (The snapshot code does a GC so all
>> real free objects are gone by this time).
> 
> Doesn't the image start with some header bytes (512 in the case of Unix)
> which end up loaded into the start of the heap? Or do these get stripped
> away at some point?
> 
> This reminds me of an OS I created for the iAPX286. I don't know if that
> particular processor was bad or if it was a design flaw, but jumping or
> calling to byte 0 of a segment didn't work in protected mode. So I moved
> the class pointer to the first two bytes of every segment (we had one
> object per segment and the class pointer had previously been a part of
> the object table) and the bug didn't bother us anymore.
> 
> -- Jecel
>