Re: [Xen-devel] [PATCH v8 4/4] xen/arm: grant: Add another entry to map MFN 1:1 in dom0 p2m

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-05-21 at 15:01 +0100, Julien Grall wrote:
> > I'm just worried that p2m type bits are in limited supply so I want to
> > be sure using new ones is justified.
> 
> We don't really need to store those type in the P2M. We only need them
> to choose the page attributes.
> 
> We could introduce a virtual type (i.e value > p2m_max_real_type) and
> store p2m_invalid in the P2M.

Will finding p2m_invalid under various circumstances not confuse
something somewhere?

How about a single real p2m_special and the virtual types you suggest?

Or, TBH, lets just use the two types you propose and do all this when we
run out... A comment to the affect that the types are only used for the
rw bit might serve as a hint to us in a couple of years that we can
easily get rid of them...

Ian.


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