From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Deegan Subject: Re: [PATCH 4 of 5] Add code to track the address of the VM generation id buffer across a Date: Mon, 28 Nov 2011 13:48:34 +0000 Message-ID: <20111128134834.GC79829@ocelot.phlegethon.org> References: <20111128123246.GB79829@ocelot.phlegethon.org> <291EDFCB1E9E224A99088639C4762022B5988E4DCC@LONPMAILBOX01.citrite.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <291EDFCB1E9E224A99088639C4762022B5988E4DCC@LONPMAILBOX01.citrite.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Paul Durrant Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org At 13:26 +0000 on 28 Nov (1322486771), Paul Durrant wrote: > > > +/* Address of VM generation id buffer */ #define > > > +HVM_PARAM_VM_GENERATION_ID_ADDR 27 > > > + > > > +#define HVM_NR_PARAMS 28 > > > > > > #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */ > > > > Since the hypervisor doesn't use this value, I don't think this is > > the right place for it to live. Tools-only VM metadata should > > probably go in xenstore or in the toolstacks' own datastructures. > > > > Yes, I was a little unsure about that. Is there any precedent for > getting information from hvmloader out to the tools? Writing guest > physical addresses into xenstore seems like the wrong thing to but > apart from HVM params or the shared hvm info page, I couldn't think of > another way apart from putting the VM generation id in a static > well-known place. Presumably in this case the tools can find the address by walking the ACPI tables, just like the guest OS would. :P Not very pretty, though. I don't think there's anything wrong with putting a GPA into xenstore. All the other tools interactions are in guest-physical addressing already. IIRC HVMloader's xenbus client doesn't have a xenstore_write() but it shouldn't be hard to add. I can't think of another way to pass data from hvmloader to the tools right now -- I think the hvm-info page should probably be replaced entirely with xenstore keys at some point. Tim.