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Re: [Xen-devel] Stability of shared info structs?

To: John Levon <levon@xxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Stability of shared info structs?
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Sun, 30 Jul 2006 18:07:34 +0100
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On 30 Jul 2006, at 13:00, John Levon wrote:

appears to have modified the size of struct arch_shared_info, as far as
I know, after the interface was supposed to be stable. This would have
broken any 3.0 domUs using the size of the shared_info structure for
whatever reason. Was this an error, or is the implication that a domU
cannot take the size of certain shared structures (and if so, which

Since shared_info is always in a Xen-provided page, we think it's okay to add extra entries to the end of it. I don't think we could get away with that with any of the other public structures.

We might add an extra field for introspection -- it depends precisely what it's for. There are one or two fields used for communicating between guest and tools, but that isn't what shared_info was originally intended for. It might, for example, be better to use xenstore.

 -- Keir

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