[Vm-dev] 64bit FFI?

Andreas Raab andreas.raab at gmx.de
Thu Feb 12 19:55:44 UTC 2009

Eliot Miranda wrote:
> Let me further suggest that 2) is pointless, in that it can't scale 
> beyond the 32-bit address space but uses about 1.5 times the space of a 
> 32-bit image as it tries to do so.  i.e. it'll fail a lot earlier than a 
> 32-bit image.  Further, if a 64-bit image is larger than will fit in a 
> 32-bit address space one *cant* run it on 2 because it won't fit. 

It is not pointless at all. If we were to switch our servers to 64 bit 
images while allowing customers to deploy on 32bit, we'd be nuts trying 
to manage both 32 and 64 bit versions of the same image and trying to 
keep them in sync. Much easier to give them a 32bit VM that can run the 
very same 64 bit image that we use everywhere.

In addition, it is this very combination that allows people without 
64bit boxes to actually help in working out the quirks with the 64bit 
images. I don't think we would have gotten where we are without it.

   - Andreas

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