Re: [boost] [context] Why does boost::ctx::minimum_stacksize() on Windows return 65536

Subject: Re: [boost] [context] Why does boost::ctx::minimum_stacksize() on Windows return 65536
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2012-09-02 14:27:11

> >>> BTW, on an unrelated note: I think the ctx::minimum_stacksize() and
> >>> ctx::maximum_stacksize() functions should be tied to the allocator.
> >>> They should not be global as they will return wrong numbers if a
> >>> custom allocator is used.
> >> good point - both functions should be part of the stack_allocator
> >> interface. I'll change it asap.
> >>
> >> What are the minimum and maximum stacksize on the several Windows
> >> versions (XP, 7, 8, Ce, R, ...)? I didn't found infos in the MSDN about
> this issue.
> >> Maybe pagesize? SUggestions?
> > Well, I can't answer this question. All I know is that VirtualAlloc
> > does not allow allocating less than a page, regardless of the
> > (Windows) system. Thus I assume the minimal stack size in
> > Boost.Context should be a page as well (well, plus guard page).
> >
> OK - following suggestion for Windows:
> 
> minimum_stacksize()/maximum_stacksize() will be static member funcs of
> class stack_allocator.
> minimum_stacksize() returns pagesize + 1kB

Why + 1kb? Shouldn't the guard page have 4k as well?

> maximum_stacksize() returns 1GB (but will never useable)
> default_stacksize()  returns 64 kB
> is_stack_unbounded() will always return true for all Windows versions
> 
> stack_allocator creates a guard page at the lower end of the stack.
> maximum_stacksize() still has ! is_stack_unbounded() as preconditon -
> which means you will/can never use the value returned by
> maximum_stacksize() until I find some informations about those limit in
> the MSDN (for the several Windows flavours).
> 
> What do you think?

Sounds good to me.

Thanks!
Regards Hartmut
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