Re: [PATCH 2/4] x86,xen: introduce x86_init.mapping.pagetable_reserve

From: H. Peter Anvin
Date: Wed Apr 13 2011 - 14:27:14 EST


On 04/12/2011 04:19 AM, stefano.stabellini@xxxxxxxxxxxxx wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> Introduce a new x86_init hook called pagetable_reserve that during the
> initial memory mapping is used to reserve a range of memory addresses for
> kernel pagetable usage.
>
> On native it just calls memblock_x86_reserve_range while on xen it also
> takes care of setting the spare memory previously allocated
> for kernel pagetable pages from RO to RW, so that it can be used for
> other purposes.
>

What are the *semantics* of this hook?

Hooks are insanely nasty if they are just defined by a particular code
flow, as evidenced by the royal mess called paravirt_ops.

-hpa
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