Re: [PATCH] mark read_crX() asm code as volatile

[H. Peter Anvin]

Nick Piggin wrote:
> > This should work because the result gets used before reading again:
> >
> > read_cr3(a);
> > write_cr3(a | 1);
> > read_cr3(a);
> >
> > But this might be reordered so that b gets read before the write:
> >
> > read_cr3(a);
> > write_cr3(a | 1);
> > read_cr3(b);
> >
> > ?
>
> I don't see how, as write_cr3 clobbers memory.

Because read_cr3() doesn't depend on memory, and b could be stored in a 
register.

	-hpa
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