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xen-devel
Re: Hypercall number assignment convension (was Re: [Xen-devel] Re:[PATC
To: |
"Tian, Kevin" <kevin.tian@xxxxxxxxx> |
Subject: |
Re: Hypercall number assignment convension (was Re: [Xen-devel] Re:[PATCH]: kexec: framework and i386) |
From: |
Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> |
Date: |
Wed, 26 Apr 2006 08:55:50 +0100 |
Cc: |
xen-devel@xxxxxxxxxxxxxxxxxxx, Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>, Isaku Yamahata <yamahata@xxxxxxxxxxxxx>, Magnus Damm <magnus@xxxxxxxxxxxxx>, Horms <horms@xxxxxxxxxxxx>, Mark Williamson <mark.williamson@xxxxxxxxxxxx> |
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Wed, 26 Apr 2006 01:00:00 -0700 |
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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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