I've been trying to isolate this problem on my <red herring> 32 bit Intel Linux </red herring> system by looking for what changed in the VMM code and the SVN platforms tree, testing the resulting VMs with the 32 bit image from squeak.hpl.hp.com/squeak64/dist3/Squeak32-3.8g-6548.image.tar.gz.
The results so far can be summarized as:
The problem was introduced in VMM code as opposed to platforms code. It was introduced in the change from VMMaker-tpr.21 to VMMaker-tpr.22. The VMMaker-tpr.22 change set contains "Merge in johnmci & ar's GC instrumentation and weak pointer changes".
Platforms version VMMaker version Result
squeak-svn-source-SVN1200 VMMaker-tpr.21 OK squeak-svn-source-SVN1200 VMMaker-tpr.22 NFG
But I discovered (entirely by accident) that I overlooked a rather large dimension of the problem. The bad (?) VM created from squeak-svn-source-SVN1200 and VMMaker-tpr.22 works just fine with an image that does not have the 64 bit changes installed. So now comparing the results from a Squeak32-3.8g-6548.image from the original ./dist3 distribution (image with 64 bit changes loaded) versus a "stock" Squeak image such as Squeak3.7-5989-basic.image or Squeak3.9a-6472.image, we have this:
Platforms version VMMaker version Image Result ----------------- --------------- ----- ------ squeak-svn-source-SVN1200 VMMaker-tpr.21 dist3/Squeak32-3.8g-6548.image OK squeak-svn-source-SVN1200 VMMaker-tpr.22 dist3/Squeak32-3.8g-6548.image NFG squeak-svn-source-SVN1200 VMMaker-tpr.21 Squeak3.7-5989-basic.image OK squeak-svn-source-SVN1200 VMMaker-tpr.22 Squeak3.7-5989-basic.image OK squeak-svn-source-SVN1200 VMMaker-tpr.21 Squeak3.9a-6472.image OK squeak-svn-source-SVN1200 VMMaker-tpr.22 Squeak3.9a-6472.image OK
Evidently the combination of the changes introduce in VMMaker-tpr.22 with the changes that were added to the Squeak32-3.8g-6548 image in ./dist3, and maybe or maybe not in combination with a 32 bit Intel Linux platform, are what cause the problem to be present.
I have not tried any other experiments yet, but I thought I should report this in case anyone is losing sleep over the problem right now.
My next steps (but not tonight) will be to try adding some or all of VMM38b4-64bit-image1-ikp.1.cs, VMM38b4-64bit-image2-ikp.1.cs, and System-Tracing.2.cs to a "stock" image and see if one of them induces the problem when running on a "bad" VM built from squeak-svn-source-SVN1200 and VMMaker-tpr.22.
Dave