sweep failed to find exact end of memory

Avi Bryant avi at dabbledb.com
Wed Feb 21 20:00:03 UTC 2007


On 2/21/07, tim Rowledge <tim at rowledge.org> wrote:
>
> On 21-Feb-07, at 10:58 AM, Avi Bryant wrote:
>
> > On 2/21/07, tim Rowledge <tim at rowledge.org> wrote:
> >
> >> It's an old issue; look up assorted reports of problems with > 2Gb
> >> pointers. The VM code is mostly written under the assumption that
> >> singed integers suffice for pointers and we really need to fix that.
> >> It's an issue of available time.
> >
> > Do you have an estimate, hopefully under 1 million euros, of what it
> > would take to fix this?
>
> That's a distressingly difficult question to answer. I bet there are
> some nasty hacks one could do that would 'fix' it on the basis of
> forcing the C compiler to do signed-unsigned conversions but... I
> never trust a C compiler. Aside from Slang code there are of course
> the primitives and platform code that would be indirectly affected,
> if only at the level of "I have change this decl to stop an oodleplex
> of compiler warnings obscuring a real problem". There's also a
> boatload of VMMaker patches needing proper integration anyway and it
> would stupid not to do them as well.
>
> I'd love to say, "oh a week" but long experience suggests that the
> truth is normally "double the digits and up the unit" so probably
> 'two months' is higher in the truthiness scale.

Avoiding hacks and warnings and integrating VMMaker patches are all
laudable things, but do you even have two months to spare, funded or
no?  What would it take to get a temporary fix to this bug, however
ugly?  I've seen it myself and can be a bit of a showstopper if you
like to work with large images.  We could certainly pay for a week of
someone's time to do this if that was an option.

Avi



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