From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hopwood Subject: Re: frontend and backend devices and different types of hw - pci for example Date: Sun, 04 Sep 2005 14:35:44 +0100 Message-ID: <431AF830.2000700@blueyonder.co.uk> References: <200509040423.51526.mark.williamson@cl.cam.ac.uk> Reply-To: david.nospam.hopwood@blueyonder.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200509040423.51526.mark.williamson@cl.cam.ac.uk> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Mark Williamson wrote: > While I'm on the subject, I'd personally like to see guests granted IO access > slightly differently. There are two ways to grant IO access on x86: change > the IOPL (giving the guest access to all IO ports) or set IO bits in the TSS > (giving fine grained control). The problem with the latter is that guest > *apps* will be able to access the hardware; essentially x86 gives you coarse > grained control and ring-level protection, or vice-versa. Could XenLinux use a different TSS to run its apps? -- David Hopwood