-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Keir Fraser escreveu: > On 1/11/07 15:30, "Jeremy Fitzhardinge" <[EMAIL PROTECTED]> wrote: > >> Glauber de Oliveira Costa wrote: >>> I in fact have seen bugs with mixed reads and writes to the same cr, >>> (cr4), but adding the volatile >>> flag to the read function seemed to fix it. >> Well, volatile will make a read be repeated rather than caching the >> previous value, but it has no effect on ordering. > > volatile prevents the asm from being 'moved significantly', according to the > gcc manual. I take that to mean that reordering is not allowed. > According to a gcc developer to whom I asked this question, volatile prevents the code to be removed, but does not prevent it to be moved (pun indented). In practice, it should force a re-read, but not influence the ordering decisions from the compiler. Besides , 'significantly' sounds like a significantly unprecise word, whose specific meaning may be implementation dependant.
So I agree that adding a memory location reference is probably the best alternative. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Using GnuPG with Remi - http://enigmail.mozdev.org iD8DBQFHKftDjYI8LaFUWXMRAiLTAKDqf/M8umNYw6u7r9ONozTEUVy8SwCgygma jWNKQmxmLpyPxr00KbQy9Vg= =JM4K -----END PGP SIGNATURE----- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
