Re: Experimental dynamic memory allocation of postgresql shared memory

On Mon, Jun 20, 2016 at 12:40 PM, Craig Ringer <craig@2ndquadrant.com> wrote:
> On 18 June 2016 at 02:42, Robert Haas <robertmhaas@gmail.com> wrote:
>>
>> On Fri, Jun 17, 2016 at 2:23 PM, Aleksey Demakov <ademakov@gmail.com>
>> wrote:
>> > Essentially this is pessimizing for the lowest common denominator
>> > among OSes.
>>
>> I totally agree.  That's how we make the server portable.
>>
>> > Having a contiguous address space makes things so
>> > much simpler that considering this case, IMHO, is well worth of it.
>>
>> I think that would be great if you could make it work, but it has to
>> support Linux, Windows (all supported versions), MacOS X, all the
>> various BSD flavors for which we have buildfarm animals, and other
>> platforms that we currently run on like HP-UX.   If you come up with a
>> solution that works for this on all of those platforms, I will shake
>> your hand.  But I think that's probably impossible, or at least
>> really, really hard.
>
>
> Indeed. In particular, ASLR on Windows or anywhere we EXEC_BACKEND will
> cause difficulties attaching to those segments.

ASLR that we currently disable in the build because Win8/2k12 and
newer versions behaves differently than past OSes in the address
mapping, making the problem even harder if we'd want to have both
working.
-- 
Michael