[lttng-dev] [liburcu PATCH 3/3] Add configure check for GCC atomic builtins

[Mathieu Desnoyers]

* Yannick Brosseau (yannick.brosseau at gmail.com) wrote:
> On 2012-01-06 10:38, Mathieu Desnoyers wrote:
> > * Alexandre Montplaisir (alexandre.montplaisir at gmail.com) wrote:
> >> I tested it on x86_64, this should be tested on other arches before
> >> merging, namely to make sure it catches GCC version below 4.4 on ARM.
> > We don't use these builtins on x86, we use our own implementation
> > instead. This check does not take into account that some gcc versions
> > support the builtin, and compile something out of it, but the semantic
> > of the barrier is wrong, which will lead to runtime races. This check
> > would be acceptable if:
> >
> > 2) it would additionally have gcc version checks for those which had a
> >    broken implementation in the first gcc versions.
> >
> Do we have a list of broken gcc or a mean to test that they are broken?
> 

README of userspace rcu:

ARM depends on running a Linux kernel 2.6.15 or better, GCC 4.4 or
better.

We have a list.

Mathieu


-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com