It doesn't even compile: http://dpaste.dzfl.pl/ec0f5183e42e

On Sat, 20 Feb 2016 17:04:11 +0000, Kagamin wrote:

> It doesn't even compile: http://dpaste.dzfl.pl/ec0f5183e42e

Check the error. Add a `cast(size_t)` in there. Try again.

That's still doomed to failure. You're not leaving space for the stack (which has preallocated address space) or application binary (which is memory mapped from the file and takes up address space). You're using the garbage collector, which has to allocate its own internal data structures somewhere.

If you subtract those from your allocation request, you still won't see much success. There's no guarantee where in memory those items will be allocated, and if your system has ASLR turned on by default, it's even less predictable.

If you tried a similar thing in C, you'd see the same problems.

On Saturday, 20 February 2016 at 17:04:11 UTC, Kagamin wrote:
> It doesn't even compile: http://dpaste.dzfl.pl/ec0f5183e42e

This looks like it's a limit purely on the interface for allocating arrays from the GC.

i.e,

ubyte* ptr;
ubyte arr = ptr[0 .. size_t.max];

compiles just fine

On Saturday, 20 February 2016 at 17:21:42 UTC, Chris Wright wrote:
>
> That's still doomed to failure. You're not leaving space for the stack (which has preallocated address space) or application binary (which is memory mapped from the file and takes up address space). You're using the garbage collector, which has to allocate its own internal data structures somewhere.

Let's not forget that you need 18 exabytes of ram too. And you want it initialized? That's going to take a while ;)

-Steve

On Sat, 20 Feb 2016 18:07:59 +0000, Steven Schveighoffer wrote:

> On Saturday, 20 February 2016 at 17:21:42 UTC, Chris Wright wrote:
>>
>> That's still doomed to failure. You're not leaving space for the stack (which has preallocated address space) or application binary (which is memory mapped from the file and takes up address space). You're using the garbage collector, which has to allocate its own internal data structures somewhere.
> 
> Let's not forget that you need 18 exabytes of ram too.

Point. The GC uses calloc, which does happen to complain when I ask for vast amounts of memory. There are other ways of requesting address space, though, such as mmap(2).