Re: [PATCH] x86/mm/init: respect memblock reserved regions when destroying mappings

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

On Mon, 7 Feb 2011, Yinghai Lu wrote:
> On 02/07/2011 08:50 AM, Stefano Stabellini wrote:
> > On Sun, 6 Feb 2011, Yinghai Lu wrote:
> >> On 02/05/2011 11:30 PM, H. Peter Anvin wrote:
> >>> On 02/05/2011 11:02 PM, Yinghai Lu wrote:
> >>>> why not just move calling cleanup_highmap down?
> >>>>
> >>>> something like attached patch.
> >>>
> >>> This patch looks very clean and looks on the surface of it like it is
> >>> removing some ugly ad hoc code, but (as always) it needs a description
> >>> about the problem it solves and why it is correct.
> >>
> >> Sure.
> >>
> >>
> >> Jeremy and xen guys, can you please check if it works well with xen ?
> >>
> > 
> > Actually this patch makes things worse on xen, because before
> > cleanup_highmap() wasn't called at all on xen (on purpose) and now it
> > is, fully destroying all the mappings we have at _end.
> > 
> > Can we add a check on memblock reserved regions in cleanup_highmap()?
> > Otherwise could we avoid calling cleanup_highmap() at all on xen?
> 
> why DO xen need over-mapped kernel initial mapping?
> 
> what is in that range after _end to 512M?

The mfn list that is the list of machine frame numbers assigned to this
domain; it is used across the kernel to convert pfns into mfns.
It passed to us at that address by the domain builder.