From mboxrd@z Thu Jan 1 00:00:00 1970 From: tgh Subject: Re: question about machine-to-physic table and phy-to-machine table Date: Mon, 26 Mar 2007 09:39:56 +0800 Message-ID: <4607246C.1060709@ncic.ac.cn> References: <45F93B96.76E4.0078.0@novell.com> <460333B8.70307@ncic.ac.cn> <1174650272.3803.29.camel@lapbode42.lrr.in.tum.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1174650272.3803.29.camel@lapbode42.lrr.in.tum.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Daniel Stodden Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Thank you for your reply >> I am confused about the meaning and function of machine-to-physic address >> > > it *is* confusing, admittedly. in my understanding, one reaseon for > 'm2p'/'p2m' being used is that guest operating systems, most prominently > linux, have always been using 'pfn' for 'page frame number' and the like > when referring to 'physical' memory. now you need some kind of > distinction in the paravirtual guest case, because those oses will deal > with both. > in the paravirt case, guestos maintain its own mfn which need m2p and p2m ,is it right? I am confused about how does guestOS maintain its virt-to-physic and physic-to-mach mapping ,in the linux ,there is only v2p mapping, how does guestOS maintain its p2m mapping ,and when a virt address is put into a mmu, does cpu hardware convert virt-addr into machine address or guest's phyiscal address? I am confused about it could you help me Thanks in advance > that host memory becoming a non-contiguous, non-physical one clearly > doesn't justify to substitute the names all across the kernel codebase. > equally, you could not name it virtual or similar in the vmm, because > the term 'virtual' has obviously been allocated elsewhere. > > so host memory became 'machine' memory. in a different universe, it > might have rather been the actual 'physical' one. or 'host' memory. > virtual machine memory got a 'p' like in both 'pseudo-physical' and/or > 'pfn' and i suppose turned for a significant number of people into > 'physical' at some point. which is largely misleading. > > regards, > daniel > >