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

Jeremy Fitzhardinge
2007-04-23T16:34:26Z

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?

J