Jeremy Fitzhardinge wrote:
I never merged the whole bit upstream because it added a field to
struct page.
Hm, is that a big problem? It would be OK for a debug config option,
wouldn't it? Also, it doesn't seem particularly vmi-specific. Could
it be made part of the pvops infrastructure?
I though about it, but it gets really ugly. You need wrappers for all
the MMU ops in pvops generic code, which means either another layer of
wrappers or a bunch of CONFIG_DEBUG_PARAVIRT only things that are easy
to break because they also depend on PAE vs. non-PAE.
It's doable, though, and might even be extensible to s390 for CMM page
type debugging, as well as descriptor type tracking and enforcement of
page isolation of GDTs.
Page state tracking could track -
PAGE_ZERO, PAGE_UNUSED, PAGE_STABLE, PAGE_VOLATILE,
PAGE_POTENTIALLY_VOLATILE, PAGE_L1{2/3/4}, PAGE_LDT, PAGE_GDT,
actually, no this seems silly, since we'd just be duplicating bits for
the page types, so the only debug benefit is ensuring the intersection
of volatile and L{1/2/3/4} is nil, which is already trivially verifiable
by inspection.
Zach
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