From mboxrd@z Thu Jan  1 00:00:00 1970
From: Big Strong <fangtuo90@gmail.com>
Subject: Re: xc_altp2m_set_vcpu_enable_notify fail
Date: Sat, 7 May 2016 15:34:34 +0800
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To: Wei Liu <wei.liu2@citrix.com>
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>
> libxc functions always return -1 when it fails. You need the specific
> errno to know what went wrong.


Yeah, I know it means a failure. Actually, I noticed that there is a
comment at the source code of xen
<http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=tools/libxc/xc_altp2m.c;hb=3e9b0d540837c4641783adcc5449d3762469ff9d#l71>,
which says :

"This is a bit odd to me that it acts on current..  it return -1 directly"

which is exactly about xc_altp2m_set_vcpu_enable_notify.  In my case,
xc_altp2m_set_vcpu_enable_notify always return -1 just as the author
comments.Besides, I've also found no existing usage about this function all
over the Internet. So I'm wondering if this function actually works or not.
Anyway, why would the author comments that? @Ian @Tamas


Do you have any difficulty debugging Xen? We might be able to give some
> pointers on how to do that.


Yeah, I've enabled debug option when compiling xen, what else steps should
I take to use a remote gdb to debug xen instead of dom0 or domU?

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<div dir=3D"ltr"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px =
0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-l=
eft-style:solid;padding-left:1ex"><span style=3D"font-size:14px">libxc func=
tions always return -1 when it fails. You need the specific<br></span><span=
 style=3D"font-size:14px">errno to know what went wrong.</span></blockquote=
><div><br></div><div>Yeah, I know it means a failure. Actually, I noticed t=
hat there is a comment at the <a href=3D"http://xenbits.xen.org/gitweb/?p=
=3Dxen.git;a=3Dblob;f=3Dtools/libxc/xc_altp2m.c;hb=3D3e9b0d540837c4641783ad=
cc5449d3762469ff9d#l71">source code of xen</a>, which says :</div><div>=C2=
=A0</div><div>&quot;This is a bit odd to me that it acts on current.. =C2=
=A0it return -1 directly&quot;</div><div><br></div><div>which is exactly ab=
out=C2=A0xc_altp2m_set_vcpu_enable_notify.=C2=A0 In my case, xc_altp2m_set_=
vcpu_enable_notify always return -1 just as the author comments.Besides, I&=
#39;ve also found no existing usage about this function all over the Intern=
et. So I&#39;m wondering if this function actually works or not. Anyway, wh=
y would the author comments that? @Ian @Tamas</div><div><br></div><div><br>=
</div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;b=
order-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:s=
olid;padding-left:1ex"><span style=3D"font-size:14px">Do you have any diffi=
culty debugging Xen? We might be able to give some<br></span><span style=3D=
"font-size:14px">pointers on how to do that.</span></blockquote><div><br></=
div><div>Yeah, I&#39;ve enabled debug option when compiling xen, what else =
steps should I take to use a remote gdb to debug xen instead of dom0 or dom=
U?=C2=A0</div></div>

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