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Re: [Xen-devel] Hypercall-page initialization

On 7 Feb 2006, at 18:04, Jacob Gorm Hansen wrote:

Or if you want to fill it in from within the domU, how about if we did
something like reserve some space of MSRs for Xen use (e.g., hex
Bxxxxxxx). Then we could say that, if the guest writes an MFN to a
particular one of those MSRs, it gets filled with hypercall-page
goodness. :-)

Hmm would that work in paravirt mode also? I guess Xen would trap the
exception and do the right thing? I suppose this has the advantage of
avoiding any hardcoded trap vectors.

Yes, although it does sound kinda gross, it will work and ultimately I think it sounds quite attractive compared with the alternatives. Not sure how to decide what MSR range to pick to reserve... Apart from that it's trivial to implement.

 -- Keir

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