VM-beginners January 2011

vm-beginners@lists.squeakfoundation.org

5 participants
9 discussions

Small bug in Win32/Cog VM
by Alexander Lazarević 27 Jan '11

27 Jan '11

Just a minuscule bug. Start the vm like this Croquet.exe bonkers.image where bonkers.image does not exist. A Windows FileDialog opens and select some existing image. Now SystemAttribute 1 should return "full path name of this image". But instead you get bonkers.image. Alex

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Simulating with the 2.7 image
by Chris Cunnington 24 Jan '11

24 Jan '11

http://www.smalltalktelevision.com/Capture.PNG So I got this running on an older, smaller image. I think it's going to open up a lot of avenues for exploring how the vm works. Cool stuff. Chris

2 1

Simulator
by Chris Cunnington 24 Jan '11

24 Jan '11

>Chris, maybe too late, but could you solve it? If true, please let us know >how. Funny you should ask... http://www.youtube.com/watch?v=2J1yjWtuwJU Chris

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Simulator
by Chris Cunnington 24 Jan '11

24 Jan '11

I'm trying Craig's ( http://wiki.squeak.org/squeak/2465 ) instructions for starting the simulator. In principle it seems pretty straight ahead. Make two images and then start one from within the other. I "SaveAs..." to make two images (source.image and stimulator.image), execute: (InterpreterSimulatorLSB new openOn: 'source.image') test And then I get an "Incompatible Image Format" error. Any suggestions on how to resolve that would be great. This does seem to be how vms are hacked. I have a feeling it's not the only way, but it must be the coolest. Chris openOn: fileName extraMemory: extraBytes ... snip ... (self readableFormat: version) ifTrue: [swapBytes := false] ifFalse: [(version := self byteSwapped: version) = self imageFormatVersion ifTrue: [swapBytes := true] ifFalse: [self error: '*incompatible image format*']].

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Simulator 2
by Chris Cunnington 18 Jan '11

18 Jan '11

I think I created a better rig. Leaving Cog out of the picture seems to work better. A standard image from squeak.org with VMMaker loaded in from MetacelloRepository. I create a fullscreen stimulator.image with the code in the workspace: /(InterpreterSimulatorLSB new openOn: 'source.image') test/ Then open the stimulator image and execute. I get the satisfying "Object Pointer Relocating" message and it's on its way. I then get a ByteSymbol>>coerceTo:sim: error stemming from Interpreter>>addNewMethodToCache While this could work, I don't get the impression that this is how people hack the vm: activating the simulator; getting the satisfactory image; generate C files to compile. I bet people hack the methods in the Interpreter class directly. I bet that's faster than getting the simulator to work and then doing things in slow motion with the slow simulator. The simulator is more historical than practical, I'm thinking. Chris

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MicroSqueak's Interpreter
by Chris Cunnington 10 Jan '11

10 Jan '11

OK, I'm looking at this the wrong way around. "Squeak is a Smalltalk written in itself." Work from the image outward. From the Interpreter, ObjectMemory, and BitBltsimulation. The relevant classes are in the 3.6 image, which is good. Thanks, Chris

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MicroSqueak's Interpreter
by Chris Cunnington 09 Jan '11

09 Jan '11

MicroSqueak comes with an Interpreter class. InterpreterSupportCode writeMacSourceFiles spits out: msq.h msqFilePrims.c msqMain.c msqMiscPrims.c projectArchive.sit (which opens up into MicroSqueak VM.proj) The README mentions an interp.c, which doesn't appear anywhere. These files are from 1999 and PPC, so I'd imagine compiling from these is not feasible. But they point to an interesting direction for learning how to make a vm: a tiny set of files. sq.h and interp.c are clearly required. The README gives the impression the .c files are where the options are. Connecting to to stdio.h is important, of course. A good approach would be to have somebody list equivalent files produced by the current VM. Maybe /platforms/Cross/vm: sq.h sqMemoryAccess.h sqNamedPrims.c sqVirtualMachine.c sqVirtualMachine.h and, /platforms/unix/src/interp.c If somebody could point to a subset of what the VMBuilderTool produces, I think it could go a long way to making vm hacking more approachable. I understand that any file set would need some doctoring, but even so, looking at five files is something that wouldn't make a beginner balk. Any suggestions as to a tight subset for me to explore and compile on my Mac using the process described in Adrian's blog would be greatly appreciated. Then I could see the relationship to MicroSqueak's 56k image. :) Actually, I guess you have to see what the image does and then work back to the capabilities available in the vm. Anyway...you get the idea. Chris

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MicroSqueak's Interpreter
by Chris Cunnington 09 Jan '11

09 Jan '11

The majority of functions in: http://isqueak.org/PlatformVMAPI are cited in /Cross/vm/sq.h. The exceptions are secCanDeletePathOfSize or dir_Lookup and related. These are in plugins. So reading over sq.h is a good place to start. Getting gnu-interp.c and the files that have implementations sq.h functions. At this point it makes sense to organize it with XCode into a project. - sq.h - gnu-interp.c - files with sq.h mentioned functions I have a feeling this set of files will have a lower noise-to-signal ratio than poking around in the VMMakerTool, which - truth be told - has some sophisticated pieces. Righto Chris

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MicroSqueak's Interpreter
by Chris Cunnington 08 Jan '11

08 Jan '11

A fully documented subset. That looks like a good place to start. Thanks! Chris

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VM-beginners January 2011