Re: [PATCH 1/1] Fixup write permission of TLB on powerpc e500 core

From: Benjamin Herrenschmidt
Date: Mon Jul 18 2011 - 00:08:02 EST


On Mon, 2011-07-18 at 13:53 +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2011-07-18 at 09:14 +1000, Benjamin Herrenschmidt wrote:
>
> > In fact, with such a flag, we could probably avoid the ifdef entirely, and
> > always go toward the PTE fixup path when called in such a fixup case, my gut
> > feeling is that this is going to be seldom enough not to hurt x86 measurably
> > but we'll have to try it out.
> >
> > That leads to that even less tested patch:
>
> And here's a version that builds (still not tested :-)
>
> Shan, can you verify whether that fixes the problem for you ?
>
> I also had a cursory glance at the ARM code and it seems to rely on the
> same stuff as embedded powerpc does for dirty/young updates, so in
> theory it should exhibit the same problem.
>
> I suspect the scenario is rare enough in practice in embedded workloads
> that nobody noticed until now.

Ignore that bogus send, I sent a proper one immediately after (evolution
FAIL, sorry about that)

Cheers,
Ben.


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