Re: the P2M/VP patch merge plan (was Re: [Xen-ia64-devel] [PATCH][RFC][TAKE5] the P2M/VP patches)

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Mardi 25 Avril 2006 03:28, Isaku Yamahata a écrit :
> On Mon, Apr 24, 2006 at 04:21:27PM +0200, Tristan Gingold wrote:
> > just a question: is P2M/VP SMP-h/g safe ?
> > Please do the merge even if not yet SMP ready.  I will work to re-enable
> > SMP.
>
> Unfortunately no for both SMP-h/g.
> It doesn't boot without nosmp xen boot option because the P2M table
> is not protected at least.
> A lock sould be introduced to protect it.
> Please define a wrapper function, something like p2m_lock()/p2m_unlock().
> Prehaps read/write spin lock might be better for performance,
> but it can be tuned later. We should use simple spin lock as a first step.
>
> I'm guessing that there may be a race between TLB/vhpt fulsh and
> p2m conversion, but I'm not sure.
> Carefull code analysis is required.

Ok, I will work now to make P2M/VP SMP ready.

Also I would have liked to enable tlb flush after grant_unmap, but your patch 
already does the job (although not very efficiently).  So I decided to 
postpone this work.

Tristan.





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