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RE: [Xen-ia64-devel] CPL of linux


  • To: "Tristan Gingold" <Tristan.Gingold@xxxxxxxx>, <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>
  • Date: Thu, 9 Mar 2006 09:59:48 -0800
  • Delivery-date: Thu, 09 Mar 2006 18:00:27 +0000
  • List-id: Discussion of the ia64 port of Xen <xen-ia64-devel.lists.xensource.com>
  • Thread-index: AcZDVunckFXYCtURSd+GUtOZyxvEhwAS7Nzw
  • Thread-topic: [Xen-ia64-devel] CPL of linux

I'm surprised to hear that both are used.  Perhaps CPL1
for fully virtualized and CPL2 for paravirtualized?

I think on Xen/x86, PL=1 is used.  On Xen/ia64, PL=2 is
used (or so I thought!).  The reason is that vBlades
used PL=1 for the I/O+management domain which was
isolated from normal guests by this privilege level
difference.  I've always thought that there might be
good reasons in the future for domain0 to be more
privileged than domU so never switched to Xen/x86's
PL=1.

Whether PL=1 or PL=2 probably doesn't matter unless some
guest kernel may accidentally get switched between them.
But if that happened, I'd assume we'd see a kernel
BUG pretty quickly.

Dan 

> -----Original Message-----
> From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf 
> Of Tristan Gingold
> Sent: Thursday, March 09, 2006 1:57 AM
> To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-ia64-devel] CPL of linux
> 
> Hi,
> 
> does Linux run in CPL 1 or in CPL 2 ?
> It seems both are used!
> 
> Tristan.
> 
> 
> _______________________________________________
> Xen-ia64-devel mailing list
> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-ia64-devel
> 

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