Re: [PATCH 10/28] i386: map enough initial memory to create lowmemmappings

[H. Peter Anvin]

Jeremy Fitzhardinge wrote:
> Eric W. Biederman wrote:
> > The only way to ensure this will not happen is to do what we do
> > on x86_64 and map the new page table page into our address space
> > before we write to it.  Assuming the page we allocate is already
> > mapped is simply not robust.
> >   
>
> So you mean make alloc_bootmem make sure there's a mapping for the
> returned page?  That would be simple enough, though it might interact
> strangely with the actual construction of the memory mappings (what if
> the page alloc_bootmem just allocated for the pagetable is the page
> pagetable_init is actually trying to map?).
>
> I'm not sure about the issue with holes.  I assume you mean that just
> because head.S maps a chunk of memory, it isn't necessarily available
> for allocation because its a hole.  But does alloc_bootmem know to avoid
> them anyway?  Has it already parsed e820 at that point?

Since we allocate the maximum possible memory statically, I fail to see 
how holes could make the situation any worse, or better.

	-hpa
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