Re: Subtle MM bug

Eric W. Biederman (ebiederm@xmission.com)
14 Jan 2001 23:59:23 -0700


Ralf Baechle <ralf@uni-koblenz.de> writes:

> On Fri, Jan 12, 2001 at 09:11:43PM +0000, Russell King wrote:
>
> > Eric W. Biederman writes:
> > > Hmm. I would think that increasing the logical page size in the kernel
> > > would be the trivial way to handle virtual aliases. (i.e.) with a large
> > > enough page size you can't actually have a virtual alias.
> >
> > There are types of caches out there that no matter how large the page size,
> > you will always have alias issues. These are ones where the cache lines
> > are indexed independent of virtual address (and therefore can have funny
> > cache line replacement algorithms).
> >
> > And yes, you guessed which processor has it. ;)

Odd. Does this affect correctness?

> I recently spoke with some CPU architecture researcher at some university
> about cache architectures; I suspect in the near future we'll see more
> funny cache indexing and replacment algorithems ...

But I doubt many of those will run incorrectly if just less efficiently if
the OS doesn't help you avoid aliases.

Eric
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