Re: [Xen-ia64-devel] Re: [PATCH]: ptc.ga for SMP-g

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Jeudi 30 Mars 2006 16:17, Isaku Yamahata a écrit :
> On Thu, Mar 30, 2006 at 04:59:35PM +0800, Xu, Anthony wrote:
> > There seems no issue, because vcpu_purge_tr_entry() only sets ->p=0.
> > In some cases, this patch may cause a not-present tlb inserted into
> > machine TLB, this is harmless, when guest accesses this page, page not
> > present fault happens, and guest kernel will purge this tlb and insert a
> > new one, there are a little performance penalty.
> > Sine you will send IPI to flush vhpt later, why not purge this tlb as
> > well as flush vhpt.
>
> Page not present fault is different from tlb miss fault.
> So guest OS may handle them differently.
> For example, suppose guest OS is Linux and a area covered by dtlb
> is from PAGE_OFFSET + 64MB. In this case Linux results in kernel panic.
PAGE_OFFSET + 64MB is covered by a tr, isn't it ?

Tristan.



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