Re: [PATCH 02/11] x86/kexec: Add extra pointers to transition pagetable PGD, PUD, PMD and PTE

From: Daniel Kiper
Date: Mon Oct 01 2012 - 09:02:06 EST


On Fri, Sep 28, 2012 at 08:56:50AM +0100, Jan Beulich wrote:
> >>> On 27.09.12 at 20:06, Daniel Kiper <daniel.kiper@xxxxxxxxxx> wrote:
> > Some implementations (e.g. Xen PVOPS) could not use part of identity page
> > table to construct transition page table. It means that they require separate
> > PUDs, PMDs and PTEs for virtual and physical (identity) mapping. To satisfy that
> > requirement add extra pointer to PGD, PUD, PMD and PTE and align existing
> > code.
>
> I'm puzzled by this - why would you need to reintroduce what had
> been dropped a long time ago, when the forward ported kernels
> don't need it? Xen itself doesn't need the extra entries, their
> presence is purely a requirement of the specific kernel
> implementation afaict.

Hmmm... I will try to optimize that a bit.

Daniel
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