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

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>Sent: 2006年4月26日 15:56
>
>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

OK, that makes sense.

Thanks,
Kevin

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