[Vm-dev] Re: Need a good comment for SystemTracerSpur (was: Tracing a Spur Image from Smalltalk)

David T. Lewis lewis at mail.msen.com
Fri Jun 3 15:14:55 UTC 2016


Tim,

Sure, of course it is ok to update it a few weeks from now. Thanks for the
follow up!

Dave

>
> Hi David,
>
> sorry for dropping this and not having time to put more work into it.
> You're
> right, this will get confusing.
>
> Right now the Spur format tracer can trace Spur format images to Spur.
> Those
> will load on a Spur VM. I have (locally, or maybe I also pushed it) code
> to
> also trace V3 images to Spur, and those won't load on Spur VMs, but they
> do
> load on RSqueak, which was one of my use cases.
>
> Marcel Taeumel and I were discussing where to go with this and that it
> might
> be useful to have support through the SystemTracing package for
> cross-tracing images between different formats. Imagine that you are
> working
> on a 64-bit Sista-enabled VM on your x86 machine and you want to move to
> (maybe) and older 32-bit ARM system without a Sista VM or to SqueakJS
> which
> doesn't support Spur (yet): We'd like the "Save As.." dialog to offer the
> choice of word size and format as well, and use the SystemTracing package
> to
> convert between the formats. This might also be useful to convert the
> Etoys
> images into the newer format without losing the in-image content and then
> using RSqueak or something to do the necessary adjustments to get it to
> load
> on the Spur VMs.
>
> I will get back to this soon, I hope, but it will be a couple more weeks
> before I have time again. Is that alright to leave it be until then?
>
> Best,
> Tim
>
>
> David T. Lewis wrote
>> Hi Tim,
>>
>> The latest version of your system tracer for Spur (on squeaksource) is
>> in SystemTracing-tfel.41. The SystemTracerSpur class would benefit from
>> a class comment to explain with it can (and cannot) do. Would you mind
>> adding a comment to clarify?
>>
>> My understanding is that SystemTracerSpur traces a 32-bit V3 image to
>> 32-bit Spur, although it is not clear if the traced image can then be
>> run under a Spur VM (I suspect not, but I am not sure). We also have
>> 64-bit Spur images available, and these will require tracing support
>> either with SystemTracer, or using the VMMaker tracing that Eliot has
>> already provided. So I think that this might get confusing soon, and
>> a class comment will help to explain it.
>>
>> Thanks!
>>
>> Dave
>>
>> On Fri, Feb 26, 2016 at 07:59:04AM -0800, timfelgentreff wrote:
>>>
>>> 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
>>> up.
>>>
>>> So my question is, what assumptions could there be, and where could I
>>> start
>>> looking.
>>>
>>> Cheers,
>>> Tim
>>>
>>> (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
>>> Sent from the Squeak VM mailing list archive at Nabble.com.
>
>
>
>
>
> --
> View this message in context:
> http://forum.world.st/Tracing-a-Spur-Image-from-Smalltalk-tp4881224p4899020.html
> Sent from the Squeak VM mailing list archive at Nabble.com.
>




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