[Vm-dev] Re: [squeak-dev] help needed with the new FFI plugin...

stephane ducasse stephane.ducasse at gmail.com
Fri Jul 22 09:07:52 UTC 2011

In september Guido and Javier will be visiting us for 3 months and one of them will be payed to work on the project 
we exchanged about some months ago (header C parser and ....)
So at least we will get that.


On Jul 22, 2011, at 1:34 AM, Eliot Miranda wrote:

> Hi All,
>     today I committed the threaded FFI plugin along with the threaded VM and hope to be able to support people in doing threaded FFI work on the x86 platforms really soon now (Esteban, amongst others, this means you ;) ).  But to put the image-level code that uses the new FFI plugin into production the standard VM needs to be upgraded to not crash with the ExternalFunction image changes the new threaded FFI plugin wants.  The main change is that ExternalFunction changes size, gaining a stackSize inst var which is used to tell the FFI plugin how much stack spacer to reserve for marshalling (its computed on first use).  The best way for this to happen is to start using the ThreadedFFIPlugin as the standard plugin in the Interpreter VM. The ThreadedFFIPlugin overall is simpler than the old FFI plugin (no assembler support code) and better (fully reentrant).  But for this to happen we may need to implement the platform=specific parts of the ThreadedFFIPlugin (still entirely Smalltalk code) for PowerPC and ARM (and perhaps others, SPARC??).  I understand what has to be done and I can explain it to anyone interested in working on the problem, but I don't have any hardware with which I can test the results so its pretty pointless my doing the work and producing something inevitably broken.  So are there people out there who would be interested in doing the port to PPC and ARM?  It means fleshing out the classes 
>     ThreadedARMFFIPlugin ThreadedFFICalloutStateForARM
>     ThreadedPPCBEFFIPlugin ThreadedFFICalloutStateForPPC
> and having a solid understanding of how alloca works to do stack allocation and how the ABIs on ARM and PPC pass registers.
> here's hoping there are a few good low-level people who would be interested.
> Let me know.
> -- 
> best,
> Eliot

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