[Vm-dev] Tracing a Spur Image from Smalltalk

timfelgentreff timfelgentreff at gmail.com
Fri Feb 26 15:59:04 UTC 2016

I've updated the SystemTracer package to trace a Spur-format image.

This works as far as I can tell, producing a header that looks just like the
header produced by the VM and the objects written also look good. I can also
open the image in RSqueak, but not on Spur. It crashes immediately and
produces a Smalltalk backtrace that looks like it never manages to return
from the image-saving method (but the names in the Stack-trace all look ok,
leading me to believe that enough objects got written ok to figure out
classes, method names, find the right Process to run and so forth).

Curiously, the old SystemTracer2 class that writes Cog-format images also
produces images that cannot be opened by Cog VMs, only Interpreter VMs. So I
assume there are other assumptions that maybe the JIT makes when starting

So my question is, what assumptions could there be, and where could I start


(If you're wondering why I'm using the Smalltalk-level tracing at all - in
our quest to create (with RSqueakVM) a Squeak VM that runs Squeak code fast
enough that we no longer have to rely on C code from plugins or optional
primitives, we're trying to see how far we can push this, and e.g. write the
image from within itself, too.)

View this message in context: http://forum.world.st/Tracing-a-Spur-Image-from-Smalltalk-tp4881224.html
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