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Re: [Xen-devel] Question on save/restore mfn canonicalization

To: John Levon <levon@xxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Question on save/restore mfn canonicalization
From: Andres Lagar-Cavilla <andreslc@xxxxxxxxxxxxxx>
Date: Fri, 28 Sep 2007 14:55:01 -0400
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Well, when you're in school you don't have to care about breaking ABI's :)
So, the answer is then "no particular reason"?
John Levon wrote:
On Fri, Sep 28, 2007 at 12:25:28PM -0400, Andres Lagar-Cavilla wrote:

While exploring the paravirt save/restore code path, I noted a (seemingly) lack of consistency between where/who canonicalizes something and who un-canonicalizes. For example, the guest kernel canonicalizes the store and console mfn's in pre_suspend, but xc_domain_restore uncanonicalizes them before scheduling back the restored guest. The question is if there is a mandatory reason for this, or is just the way the code was written. Can I, e.g, fill the pfn_to_mfn_frame_list(_list) entries from "outside" and remove that code from post_suspend, or will something break?

You'll break the ABI. I don't know of a reason why it's so inconsistent.


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