From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: Domain Save Image Format proposal (draft B) Date: Tue, 11 Feb 2014 13:12:32 +0000 Message-ID: <1392124352.26657.120.camel@kazak.uk.xensource.com> References: <52F90A71.40802@citrix.com> <1392111040.26657.50.camel@kazak.uk.xensource.com> <52FA0C1A.5080004@citrix.com> <1392120588.26657.99.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1392120588.26657.99.camel@kazak.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: David Vrabel Cc: Shriram Rajagopalan , Stefano Stabellini , Ian Jackson , "Xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On Tue, 2014-02-11 at 12:09 +0000, Ian Campbell wrote: > > > > >> > -------------------------------------------------------------------- > > >> Field Description > > >> ----------- > -------------------------------------------------------- > > >> count Number of pages described in this record. > > >> > > >> pfn An array of count PFNs. Bits 63-60 contain > > >> the XEN\_DOMCTL\_PFINFO_* value for that PFN. > > > > > > Now might be a good time to remove this intertwining? I suppose > 60-bits > > > is a lot of pfn's, but if the VMs address space is sparse it isn't > out > > > of the question. > > > > I don't think we want to consider systems with > 64 bits of address > > space so 60-bits is more than enough for PFNs. > > Is it? What about systems with 61..63 bits of address space? Nevermind, another reply in the thread reminded me that these are PFNs, so 64-bit PFN == 72 bits of address space. Although, perhaps it would be better to spec this as nibble and a 60-bit field rather than by pretending the top of a 64-bit field is special. (or an octet and a 7 octet field if you prefer) Ian.