Messages in this thread | | | Date | Thu, 01 Nov 2007 08:30:59 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH 3/16] read/write_crX, clts and wbinvd for 64-bit paravirt |
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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.
> Yet, I agree with you that > the theorectical problem exists for the reorder, and your proposed fix > seems fine (although if we're really desperate about memory usage, we > can use a char instead a int and save 3 bytes!)
Sure. Ideally the compiler would never even generate a reference to it, and it could just be extern, but in practice the compiler will generate references sometimes.
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