From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: set_current in Xen booting sequence Date: Mon, 03 Dec 2012 17:54:39 +0000 Message-ID: References: <1354520163.12932.YahooMailNeo@web120002.mail.ne1.yahoo.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4356708209104267251==" Return-path: In-Reply-To: <1354520163.12932.YahooMailNeo@web120002.mail.ne1.yahoo.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: maheen butt , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --===============4356708209104267251== Content-type: multipart/alternative; boundary="B_3437402082_30241066" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3437402082_30241066 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable It=B9s a dummy or poison value to catch invalid use of current before it is properly set up. -- Keir On 03/12/2012 07:36, "maheen butt" wrote: > Hi all, >=20 > I'm investigating Xen bootup sequence and I'm stuck with the function > set_current((struct vcpu *)0xfffff000); > the high level idea is that it is assigning VCPU to physical CPU but I ca= n't > understand the following >=20 > 1) what is the need of this hard coded address? it is seemed that vcpu e= xist > on this address (but no idea who put vcpu on that particular address)? > (the same address is passed both in case of ARM and X86) > 2) no idea about what exactly get_cpu_info() (called by set_current) is > doing.. (logically doing & and or with sp register)? > =20 > Thanks >=20 >=20 >=20 >=20 >=20 >=20 > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel --B_3437402082_30241066 Content-type: text/html; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Re: [Xen-devel] set_current in Xen booting sequence It’s a dummy or poison value to catch invalid use of current before = it is properly set up.

 -- Keir

On 03/12/2012 07:36, "maheen butt" <maheen_butt26@yahoo.com> wrote:

Hi all,

I'm investigating Xen bootup sequence and I'm stuck with the function set_c= urrent((struct vcpu *)0xfffff000);
the high level idea is that it is assigning VCPU to physical CPU but I can'= t understand the following

1) what is the need of this hard coded address?  it is seemed that vcp= u exist on this address (but no idea who put vcpu on that particular address= )?
(the same address is passed both in case of ARM and X86)
2) no idea about what exactly get_cpu_info() (called by set_current) is doi= ng..  (logically doing & and or with sp register)?
 
Thanks





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