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Re: [Xen-devel] struct shared_info extensibility (or lack thereof)




On 28 Nov 2005, at 16:47, Rik van Riel wrote:

The reason for putting the vcpu_* structures together on a per
virtual cpu basis is that this way we can extend the number of
virtual CPUs in the future, without breaking the interface with
older guests.

The current stared_info struct of two [MAX_VIRT_CPUS] arrays
followed by the single variables is just impossible to extend
in the future.

MAX_VIRT_CPUS is already quite big (32). Increasing it to the next power-of-two will overflow the shared_info page. So, if/when we want to do that we'll place the extra vcpu info in a separate shared page.

Given how close 3.0.0 is now, I don't think this is a good change to be making.

 -- Keir


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