Re: [Xen-devel] [PATCH] Do not set page's count_info directly

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 05/03/2009 12:45, "Gianluca Guida" <glguida@xxxxxxxxx> wrote:

> On Thu, Mar 5, 2009 at 1:38 PM, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
>> The check doesn't tell you it's a shadow page -- it just tells you it's
>> *not* allocated in another way.  Checking with the mask is OK here,
>> perhaps with a comment change.
> 
> Yes, but this is what the code (in the shadow code) intends to check.
> My complete plan is to have this macro and restore the idea of having
> a flag for shadow pages because, as for now, the fact that we can't
> distinguish clearly a shadow page should be considered a sort of bug,
> given the code assumptions. Or at least a good basis for future bugs.

I'm happy for shadow code to have another bit in count_info for its own use.
I don't think it's good to have other code (e.g., generic page offlining
code) peeking at it, is all. The particular case for a new flag described
above sounds fine.

 -- Keir



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