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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 08:38:18 +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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On 26 Apr 2006, at 03:34, Tian, Kevin wrote:

I prefer to the first one. However not the current
__HYPERVISOR_arch_specific_0, *_1, *_2, ..., how about just call
it as __HYPERVISOR_arch_specific_ops which contains another
namespace defined by different architecture seperately?

Sometimes you might want a fast hypercall that doesn't have two levels of demultiplexing, or where the register/stack parameters are carefully crafted and would not fit with an ioctl()-style hypercall (see x86's IRET hypercall).

How about reserving 8 or 16 arch-specific hypercalls up front?
#define __HYPERVISOR_arch_0  32
#define __HYPERVISOR_arch_7  39

We could give a bit of breathing space to the non-arch range by starting __HYPERVISOR_arch_* at. e.g., 40 or 48?

 -- Keir

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