WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] [PATCH 02/12] early PV on HVM

To: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 02/12] early PV on HVM
From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Date: Thu, 10 Jun 2010 14:36:32 +0100
Cc: "jeremy@xxxxxxxx" <jeremy@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Stefano Stabellini <Stefano.Stabellini@xxxxxxxxxxxxx>, "Yaozu \(Eddie\) Dong" <eddie.dong@xxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "ddutile@xxxxxxxxxx" <ddutile@xxxxxxxxxx>, "sheng@xxxxxxxxxxxxxxx" <sheng@xxxxxxxxxxxxxxx>
Delivery-date: Thu, 10 Jun 2010 06:43:44 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <20100608190505.GA8560@xxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1275570645-27189-1-git-send-email-stefano.stabellini@xxxxxxxxxxxxx> <1275570645-27189-2-git-send-email-stefano.stabellini@xxxxxxxxxxxxx> <20100604202008.GB17645@xxxxxxxxxxxxxxxxxxx> <alpine.DEB.2.00.1006071518050.3401@kaball-desktop> <20100608134637.GA5998@xxxxxxxxxxxxxxxxxxx> <alpine.DEB.2.00.1006081643280.3401@kaball-desktop> <20100608161233.GA4900@xxxxxxxxxxxxxxxxxxx> <alpine.DEB.2.00.1006081714460.3401@kaball-desktop> <20100608190505.GA8560@xxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Alpine 2.00 (DEB 1167 2008-08-23)
On Tue, 8 Jun 2010, Konrad Rzeszutek Wilk wrote:
> On Tue, Jun 08, 2010 at 05:25:52PM +0100, Stefano Stabellini wrote:
> > On Tue, 8 Jun 2010, Konrad Rzeszutek Wilk wrote:
> > > On Tue, Jun 08, 2010 at 04:55:33PM +0100, Stefano Stabellini wrote:
> > > > On Tue, 8 Jun 2010, Konrad Rzeszutek Wilk wrote:
> > > > > > > > +       HYPERVISOR_shared_info = (struct shared_info 
> > > > > > > > *)shared_info_page;
> > > > > > > > +
> > > > > > > > +       /* Don't do the full vcpu_info placement stuff until we 
> > > > > > > > have a
> > > > > > > > +          possible map and a non-dummy shared_info. */
> > > > > > > 
> > > > > > > Might want to mention where the full vpcu placement is done.
> > > > > > 
> > > > > > The comment is not accurate, we actually don't do any vcpu_info
> > > > > > placement on hvm because it is not very useful there.
> > > > > > Better just to remove the comment (I have done so in my tree).
> > > > > > 
> > > > > > > > +       per_cpu(xen_vcpu, 0) = 
> > > > > > > > &HYPERVISOR_shared_info->vcpu_info[0];
> > > > > > > 
> > > > > So.. what is the purpose of the per_cpu(xen_vcpu, 0) then?
> > > > > 
> > > > 
> > > > the vcpu info placement memory area is stored in per_cpu(xen_vcpu_info, 
> > > > cpu);
> > > > per_cpu(xen_vcpu, cpu) is just a pointer to that area if it is
> > > > available, otherwise it points to the vcpu_info struct in the shared
> > > > info page.
> > > 
> > > I was just wondering why are we doing this when you say:
> > > " don't do any vcpu_info placement on hvm because it is not very useful 
> > > there."
> > > 
> > > So if it is not useful, why do it?
> > > 
> > 
> > I think Jeremy replied to your question better than me: we still need
> > the vcpu_info stuff for the timer and event channels, but we don't need
> > it to be at a specific address in kernel memory.
> 
> Ok, can you add that comment for the usage of the per_cpu(xen_vcpu,0)
> and mention that this is bootstrap code - hence only starting at CPU 0.
> 

All right, I'll do that.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel