From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hollis Blanchard Subject: Re: Re: Xen/ia64 presentation Date: Thu, 28 Apr 2005 15:11:22 -0500 Message-ID: <4271436A.4020009@us.ibm.com> References: <516F50407E01324991DD6D07B0531AD535AFC4@cacexc12.americas.cpqcorp.net> <426FE40C.60102@us.ibm.com> <426FE884.2010904@us.ibm.com> <46747f931d038af6b7606bf02b93c216@cl.cam.ac.uk> <426FF155.6050608@us.ibm.com> <768cdb9ef8393197f3d7772291d527c7@cl.cam.ac.uk> <4271271B.2000206@us.ibm.com> <38880a67d18698b906a675852e9a80b1@cl.cam.ac.uk> <4271325E.9020307@us.ibm.com> <1dffe19ca0890156a50e44ec6b974de6@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1dffe19ca0890156a50e44ec6b974de6@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: Keir Fraser Cc: "Magenheimer, Dan (HP Labs Fort Collins)" , Xen-devel List-Id: xen-devel@lists.xenproject.org Keir Fraser wrote: >> We've already seen that the only common code >> using that type is to pass to (architecture-specific) show_registers(). > > Yes. Common code never dereferences cpu_user_regs, but it needs to > receive it and pass it on. Shrug, I don't mind things how they are, especially since Dan says it works for him. It just seems silly to pass it everywhere for a single user. >> x86 can get at its state by masking off ESP. PPC can get at it via >> 'current'. Why then pass a pointer through all interrupt handlers when >> none of them care? > > No, that gets you an exec_domain (or 'vcpu', as we plan to rename it). > Or it can get you the guest's cpu_user_regs. But if you interrupted a > Xen activation then there is no way of getting at that outer > activation's register state. Ah, ok. I will have to think more about these activations. > Even Linux has a pt_regs parameter passed to every interrupt handler, so > it must surely be a good thing to do. ;-) Yes yes... :) -- Hollis Blanchard IBM Linux Technology Center