[Vm-dev] Re: [Pharo-project] SystemTracer

[Igor Stasenko]

Just want to add, that in Pharo we refactored things a bit,
so if you want to look for vm parameters, they are accessed via:

Smalltalk vm parameterAt: xyz

not
Smalltalk vmParameterAt:

look in VirtualMachine class for implementation.

On 15 March 2012 17:58, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>
> Hi Guillermo,
>
> On Wed, Mar 14, 2012 at 12:48 PM, Guillermo Polito <guillermopolito at gmail.com> wrote:
>>
>> Hi Eliot,
>>
>> do you have a pointer of where can I see the differences between the old Squeak format and the cog image format, so I can make SystemTracer work on Cog vms?
>
>
> So the image format differences are
> - floats are in platform order, not necessarily in big-endian order
> - the layout of the specialObjectsArray is slightly different (documented in recreateSpecialObjectsArray)
> - there are more words in the header, see StackInterpreter>writeImageFileIO:, i.e.
>
> in Cog:
> self putLong: self imageFormatVersion toFile: f.
> self putLong: headerSize toFile: f.
> self putLong: imageBytes toFile: f.
> self putLong: objectMemory startOfMemory toFile: f.
> self putLong: objectMemory specialObjectsOop toFile: f.
> self putLong: objectMemory newObjectHash toFile: f.
> self putLong: self ioScreenSize toFile: f.
> self putLong: self getImageHeaderFlags toFile: f.
> self putLong: extraVMMemory toFile: f.
> self putShort: desiredNumStackPages toFile: f.
> self putShort: self unknownShortOrCodeSizeInKs toFile: f.
> self putLong: desiredEdenBytes toFile: f.
> self putShort: (maxExtSemTabSizeSet ifTrue: [self ioGetMaxExtSemTableSize] ifFalse: [0]) toFile: f.
> self putShort: 0 toFile: f.
> 1 to: 4 do: [:i | self putLong: 0 toFile: f].  "fill remaining header words with zeros"
>
> in Interpreter:
> self putLong: (self imageFormatVersion) toFile: f.
> self putLong: headerSize toFile: f.
> self putLong: imageBytes toFile: f.
> self putLong: (self startOfMemory) toFile: f.
> self putLong: specialObjectsOop toFile: f.
> self putLong: lastHash toFile: f.
> self putLong: (self ioScreenSize) toFile: f.
> self putLong: fullScreenFlag toFile: f.
> self putLong: extraVMMemory toFile: f.
> 1 to: 7 do: [:i | self putLong: 0 toFile: f].  "fill remaining header words with zeros"
>
> Then
>
> getImageHeaderFlags
> "Answer the flags that are contained in the 7th long of the image header."
> ^fullScreenFlag "0 or 1"
> + (VMBIGENDIAN ifTrue: [0] ifFalse: [2]) "this is the imageFloatsLittleEndian flag"
> + (processHasThreadId ifTrue: [4] ifFalse: [0])
> + (flagInterpretedMethods ifTrue: [8] ifFalse: [0])
> + (preemptionYields ifTrue: [0] ifFalse: [16])
> + (noThreadingOfGUIThread ifTrue: [32] ifFalse: [0])
> + (imageHeaderFlags bitAnd: 63 bitInvert32) "these are any flags we do not recognize"
>
> Now most of the information in the flags is accessible from vmParameterAt: (or some convenience methods).  e.g. vm parameter 49 is the max external semaphore table size, and vm parameter 48 is the following flags:
>
> getCogVMFlags
> "Answer an array of flags indicating various properties of the Cog VM.
> Bit 0: implies the image's Process class has threadId as its 3rd inst var (zero relative)
> Bit 1: if set, methods that are interpreted will have the flag bit set in their header
> Bit 2: if set, implies preempting a process does not put it to the back of its run queue"
> ^objectMemory integerObjectOf: (processHasThreadId ifTrue: [1] ifFalse: [0])
> + (flagInterpretedMethods ifTrue: [2] ifFalse: [0])
> + (preemptionYields ifTrue: [0] ifFalse: [4])
> + (noThreadingOfGUIThread ifTrue: [8] ifFalse: [0])
>
> Read the comment for vmParameterAt: to get things like num stack pages and cog code size.
>
> Is this OK?  I know it's a bit of a mess. If you or I (we?) write it up where should we put the info?
>>
>>
>> Thanks,
>> Guille
>>
>> On Thu, Jan 27, 2011 at 6:36 PM, Levente Uzonyi <leves at elte.hu> wrote:
>>>
>>> On Thu, 27 Jan 2011, Benjamin wrote:
>>>
>>>> It works for  PharoCore-1.1-11196-UNSTABLE.1 but it seems to be the only version where it works :S
>>>>
>>>> Does someone know why ?
>>>
>>>
>>> It doesn't support Cog's image format. Try an image with the original Squeak format. You can convert your image with the latest SqueakVM. Only the unix VM was released with this feature yet, so you can use that
>>> http://squeakvm.org/unix/ or build a VM for your favorite platform.
>>>
>>>
>>> Levente
>>>
>>>
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Ben
>>>>
>>>> On Jan 27, 2011, at 3:36 PM, Benjamin wrote:
>>>>
>>>>> Hello guys,
>>>>>
>>>>> for one of my projects, I'm trying to use SystemTracer to create  anew image, but it appears that it doesn't work on Pharo ...
>>>>> I can create a new image, but I can't open it. I've tried with an older VM (Squeak 3.8.18beta1U), but it's the same ...
>>>>>
>>>>>
>>>>> Did someone already have this problem ? Does someone have a solution ?
>>>>>
>>>>>
>>>>>
>>>>> Thanks in advance,
>>>>>
>>>>> Ben
>>>>
>>>>
>>>>
>>>
>>
>
>
>
> --
> best,
> Eliot
>
>



-- 
Best regards,
Igor Stasenko.