From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: What is do_ni_hypercall() for
Date: Wed, 20 Feb 2013 01:17:27 +0000
Message-ID: <51242427.2070605@citrix.com>
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To: Xinxin Jin <xinxinjin89@gmail.com>
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On 19/02/2013 23:09, Xinxin Jin wrote:
> Hi everyone,
> I traced pv hypercalls and found that the vector "do_ni_hypercall" is
> invoked a lot. But this hypercall function does nothing (from the
> source code). So I am very confused what is do_ni_hypercall for? Why
> do guests invoke it ?
> Thanks a lot,
> -- 
> Xinxin

As expected.  It is the "Not Implemented" hypercall.  This means that
your PV guest is erroneously asking for hypercalls which are in the
permitted range (0-63) but not implemented by the hypervisor.

See xen/arch/x86/x86_64/entry.S:hypercall_table

~Andrew