Messages in this thread | | | Date | Tue, 8 May 2007 13:07:51 -0700 | From | "Satyam Sharma" <> | Subject | Re: [RFC/PATCH] doc: volatile considered evil |
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On 5/8/07, Randy Dunlap <randy.dunlap@oracle.com> wrote: > On Mon, 30 Apr 2007 23:56:42 -0700 Andrew Morton wrote: > > > Oh my eyes. What are these doing? > > > > The volatiles are a worry - volatile is said to be basically-always-wrong > > in-kernel, although we've never managed to document why, and i386 > > cheerfully uses it in readb() and friends. > > > > Perhaps if you can describe presisely what's going on here, alternatives > > might be suggested. > > [well, can be turned into a patch] > > Here are some 'volatile' comments from Linus, extracted from > several emails in at least 2 threads. > > If this is close to useful, we can add it to Documentation/.
Yes, definitely. Say Documentation/volatile-usage.txt -- this raw version could be touched a little bit, to have sections that clearly explain (1) how volatile makes the compiler generate trashy code, (2) why volatile doesn't even do what people _think_ it does, considering code is executed out-of-order by _hardware_ these days and not due to compilers like was the case 20 years back, (3) and so volatile ends up _hiding_ bugs from people and thus should be consigned to the trash can of history, (4) _except_ for _really special_ usage cases like reading IO mapped as memory. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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