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Re: Question on volatile functions and GCC
On 05/03/13 10:58, David Paterson wrote:
> On 5 March 2013 09:40, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
>> On 5 March 2013 09:27, David Paterson wrote:
>>>
>>> In addition to Jonathan's answer on the use of "volatile", it's worth adding
>>> that it's not only used for memory mapped hardware. There are many other
>>> uses, such as inter-thread communication, or indeed the example you
>>> show below.
>>
>> Only in broken code.
>
> LOL - well, it depends on your definition of "broken"...
>
>> volatile is not for multithreading, you need proper synchronization
>> for interthread communication.
"volatile" is often part of the synchronisation, but it is seldom
sufficient on its own. So it is "used in inter-thread communication" in
a sense.
>
> Not always. For very simple, non-critical uses you can just use a
> volatile flag-type variable. Cheap and nasty, I agree, but useable.
>
In some cases that is true - particularly on small processors and
embedded systems that don't have complications like caches, write
buffers, superscaler cpus, etc.
> Regards,
>
> David P.
>