From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: Re: [PATCH] Support swap a page from user space tools -- Was RE: [RFC][PATCH] Basic support for page offline Date: Fri, 20 Mar 2009 09:05:33 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Jiang, Yunhong" , Tim Deegan Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On 20/03/2009 02:52, "Jiang, Yunhong" wrote: > This requires we need to allocate the new page before the exchange call and we > have to pass both old_mfn and new_mfn in step 5 to exchange the memory. > However, current hypercall will always allocate a new page to replace the old > one. > > Currently I try to add a new hypercall for this purpose. > > Maybe we can enhance the current XENMEM_exchange to accept a mem_flags, when > that flag is set, the exch.out.extent_start will be the new_mfn instead of the > gpfn, and the gpfn will be always same as corresponding gpfn in the > exch.in.ext_start. But I do think this is a bit tricky, it change the meaning > of exch.out.extent_start and how the gpn is pass down. Thanks for the description. I guess I will wait for your next patch, which should I think at least separate the foreign pagetable update hypercall from this weird swap hypercall. Then I can comment on the new swap hypercall perhaps getting less confused by it. I certainly don't promise to get this in for 3.4 at this point however. -- Keir