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From: Andi Kleen <ak@suse.de>
To: virtualization@lists.osdl.org
Cc: Zachary Amsden <zach@vmware.com>,
	Linus Torvalds <torvalds@osdl.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Xen-devel <xen-devel@lists.xensource.com>,
	Andrew Morton <akpm@osdl.org>, Dan Hecht <dhecht@vmware.com>,
	Dan Arai <arai@vmware.com>, Anne Holler <anne@vmware.com>,
	Pratap Subrahmanyam <pratap@vmware.com>,
	Christopher Li <chrisl@vmware.com>,
	Joshua LeVasseur <jtl@ira.uka.de>, Chris Wright <chrisw@osdl.org>,
	Rik Van Riel <riel@redhat.com>, Jyothy Reddy <jreddy@vmware.com>,
	Jack Lo <jlo@vmware.com>, Kip Macy <kmacy@fsmware.com>,
	Jan Beulich <jbeulich@novell.com>,
	Ky Srinivasan <ksrinivasan@novell.com>,
	Wim Coekaerts <wim.coekaerts@oracle.com>,
	Leendert van Doorn <leendert@watson.ibm.com>
Subject: Re: [RFC, PATCH 17/24] i386 Vmi msr patch
Date: Tue, 14 Mar 2006 17:23:53 +0100	[thread overview]
Message-ID: <200603141723.54365.ak@suse.de> (raw)
In-Reply-To: <200603131812.k2DICGJE005747@zach-dev.vmware.com>

On Monday 13 March 2006 19:12, Zachary Amsden wrote:
> Fairly straightforward code motion of MSR / TSC / PMC accessors
> to the sub-arch level.  Note that rdmsr/wrmsr_safe functions are
> not moved; Linux relies on the fault behavior here in the event
> that certain MSRs are not supported on hardware, and combining
> this with a VMI wrapper is overly complicated.  The instructions
> are virtualizable with trap and emulate, not on critical code
> paths, and only used as part of the MSR /proc device, which is
> highly sketchy to use inside a virtual machine, but must be
> allowed as part of the compile, since it is useful on native.

I'm not aware of any MSR access being on a critical code
path on a 32bit kernel. 

And I don't think it's a good idea to virtualize the TSC 
without CPU support.

Why would you want to do any of this?

-Andi

  reply	other threads:[~2006-03-14 16:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-13 18:12 Zachary Amsden
2006-03-14 16:23 ` Andi Kleen [this message]
2006-03-14 16:32   ` Zachary Amsden
2006-03-14 17:43     ` Andi Kleen
2006-03-14 18:03       ` Zachary Amsden
2006-03-22 20:21 ` Andi Kleen

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