Re: Spinlocks and compiler/memory barriers

On Tue, Jul 1, 2014 at 11:22 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Jul 1, 2014 at 6:04 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>>> You know, looking at this, I wonder if we shouldn't just remove
>>> support for ARMv5 instead of making a blind stab at a fix.
>>
>> Well, I argued that way for a while ;). We don't even need to really
>> desupport it, but just say it's not supported for gcc < 4.4.
>
> Yeah, I didn't realize at the time that you were making that argument
> that the existing code was thought to be broken on its own terms.
> Removing probably-working code that we just can't test easily is, in
> my mind, quite different from removing probably-broken code for which
> we can't test a fix. By the time PostgreSQL 9.5 is released, GCC 4.4
> will be six years old, and telling people on an obscure platform that
> few operating system distributions support that they can't use a
> brand-new PostgeSQL with a seven-year-old compiler doesn't seem like a
> serious problem, especially since the only alternative we can offer is
> compiling against completely-untested code.

A few years back I ported the postresql client libraries and a few
other pieces of software (in particular subversion) to a lot of
obscure platforms (old sparc, hpux, irix, older aix, etc etc).
Getting a modern gcc working on those platforms (with the possible
exception of aix) is in many cases difficult or impossible. So
requiring new gcc is exactly equivalent to desupporting.

merlin