Re: What does atomic_read actually do?

[Paolo Ornati <ornati@fastwebnet.it>]

On Sat, 18 Dec 2004 11:23:37 -0500
"Joseph Seigh" <jseigh_02@xemaps.com> wrote:

> It doesn't do anything that would actually guarantee that the fetch
> from memory would be atomic as far as I can see, at least in the x86
> version. The C standard has nothing to say about atomicity w.r.t.
> multithreading or multiprocessing.  Is this a gcc compiler thing?  If
> so, does gcc guarantee that it will fetch aligned ints with a single
> instruction on all platforms or just x86?   And what's with volatile
> since if the C standard implies nothing about multithreading then it
> follows that volatile has no meaning with respect to multithreading
> either?  Also a gcc thing?  Are volatile semantics well defined enough
> that you can use it to make the compiler synchronize memory state as
> far as it is concerned?

http://www.gnu.org/software/libc/manual/html_node/Atomic-Data-Access.html#Atomic%20Data%20Access

http://www.gnu.org/software/libc/manual/html_node/Atomic-Types.html#Atomic%20Types

http://gcc.gnu.org/onlinedocs/gcc/Volatiles.html

-- 
	Paolo Ornati
	Gentoo Linux (kernel 2.6.9-gentoo-r6)