Re: [PATCH 3/16] read/write_crX, clts and wbinvd for 64-bit paravirt

Keir Fraser
2007-11-01T16:56:18Z

On 1/11/07 15:30, "Jeremy Fitzhardinge" <jeremy@goop.org> 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.

-- Keir