From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [PATCH] VMI: remove CONFIG_DEBUG_PAGE_TYPE and associated	bitrotted
 code
Date: Fri, 06 Jul 2007 13:28:16 -0700
Message-ID: <468EA5E0.4070501@goop.org>
References: <Pine.LNX.4.64.0707060847470.23786@localhost.localdomain>	<468E890A.1070504@s5r6.in-berlin.de>	<20070706201625.GT4306@sequoia.sous-sol.org> <468EA27C.9060401@vmware.com>
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To: Zachary Amsden <zach@vmware.com>
Cc: Chris Wright <chrisw@sous-sol.org>, Andrew Morton <akpm@osdl.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, virtualization@lists.osdl.org, Stefan Richter <stefanr@s5r6.in-berlin.de>, "Robert P. J. Day" <rpjday@mindspring.com>
List-Id: virtualization@lists.linuxfoundation.org

Zachary Amsden wrote:
> I'd rather keep it, even with bitrot - it was non-trivial to get 
> correct, and found many surprises in the code; most notably, it can 
> detect
>
> 1) PTE writes to pages not declared as page tables
> 2) Failure to allocate or de-allocate page tables using the 
> paravirt-ops API
> 3) PTE writes using the wrong level operations
>
> These are most useful properties; in fact, I would like to extend the 
> code for 64-bit paravirt-ops and 4-level paging, so rather not kill it 
> until then.
>
> 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?

    J