[Vm-dev] 64 bits

[David T. Lewis]

On Fri, May 04, 2012 at 02:36:28PM +0200, Bert Freudenberg wrote:
> 
> On 04.05.2012, at 14:21, David T. Lewis wrote:
> 
> > On Fri, May 04, 2012 at 11:59:10AM +0200, Bert Freudenberg wrote:
> >> 
> >> IMHO the most urgent need is to make the 32 bit VM compile on a 64 bit machine. Running 64 bit images would be nice, too, but the problem most users run into right now is that they just cannot easily run their current image on that shiny new box.
> >> 
> >> - Bert -
> >> 
> > 
> > I agree. Aside from the work of building and distributing these VMs, the
> > two most serious issues to be addressed are these:
> > 
> > http://bugs.squeak.org/view.php?id=7237
> > 0007237: Make FFI work on 64 bit platforms
> > 
> > http://bugs.squeak.org/view.php?id=7433
> > 0007433: Gstreamer and Pango plugins fail on 64-bit host
> > 
> > Both of these involve pointer-to-int issues affecting the image(s),
> > the Slang, and the support code on multiple platforms.
> > 
> > A set of fixes was available for the FFI issue a few years ago (but
> > not pushed through due to some other higher priorities). This could
> > presumably be updated and applied to the various FFIs now in circulation,
> > but it will take some work and coordiation of multiple branches and
> > platforms to pull it off.
> > 
> > No fix is available for the Gstreamer/Pango issue, but I regard this
> > as equally high priority because the underlying issue is in the
> > SurfacePlugin, and fixes are likely to involve updates to images,
> > VMMaker(s), and platform code.
> > 
> > Aside from these, I think that any remaining 64-bit issues are
> > likely to be easily dealt with, at least in the sense that the
> > fixes will be limited in scope and can be done without a lot
> > of image/vm/plugin/support code coordination.
> > 
> > I should say though that we are actually in much better shape
> > than might be implied by the above. I use a 64-bit VM pretty much
> > all the time on my desktop (Cog too of course) and I have no
> > problems (I don't use FFI or Pango). And a 64-bit VM is perfectly
> > suitable for server deployments. There is no problem at all for
> > someone who is aware of the limitations and willing to compile
> > their own VM. But distributing a 64-bit VM to lots of people
> > who expect it to "just work" is another matter, I don't think
> > we're there just yet.
> > 
> > Dave
> 
> 
> The OP's question was about a Cog VM compiled for x86_64 - is that easily available?
> 
> - Bert -

No, that would be a larger project. Eliot could speak to this better
than I can, but in general terms I expect that this would involve first
building a 64-bit StackVM (i.e. the current StackVM compiled in 64-bit
mode), and then developing the code generation for Cog. Both of these
would involve work above and beyond what I described above for the
interpreter VM. My assumption would be that these are large enough
chunks of work that we should not expect them to happen on a strictly
volunteer basis.

Dave