Re: Hypercall number assignment convension (was Re: [Xen-devel] Re:[PATCH]: kexec: framework and i386)

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 26 Apr 2006, at 08:54, Tian, Kevin wrote:

> Then we may need to fill that breathing space with do_ni_hypercall
> to ensure no leakage from NR_hypercall check. If that's the case,
> how about define the __HYPERVISOR_arch_* at end of 256 spaces,
> and fill all unused entries with do_ni_hypercall. By that way, the 
> check
> to illegal hypercall (<256) is a bit slower, however it shouldn't 
> matter
> for that rare cases.
Yes, it would need filling with ni_hypercall: we already do that on x86 
anyway (since hypercall table is rounded up to a power of two).
I don't want to put the hypercalls that far up: with one hypercall page 
x86 will currently have a problem implementing more than 128 
hypercalls. I also don't want to put them right at the end of the 
hypercall space because that would make it harder/uglier to add extra 
arch hypercalls later on.
I think 48-55 would be reasonable.

 -- Keir


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