From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: Linux'es free_initmem() on Xen Date: Tue, 2 Feb 2016 15:09:51 +0000 Message-ID: <56B0C6BF.7000008@citrix.com> References: <56B0B2A702000078000CD7BC@prv-mh.provo.novell.com> <56B0AF63.1050803@citrix.com> <56B0C6FE02000078000CD88E@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aQcaa-0002j6-AC for xen-devel@lists.xenproject.org; Tue, 02 Feb 2016 15:09:56 +0000 In-Reply-To: <56B0C6FE02000078000CD88E@prv-mh.provo.novell.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: Jan Beulich Cc: xen-devel , Boris Ostrovsky List-Id: xen-devel@lists.xenproject.org On 02/02/16 14:10, Jan Beulich wrote: >>>> On 02.02.16 at 14:30, wrote: >> On 02/02/16 12:44, Jan Beulich wrote: >>> All, >>> >>> while looking into some of the DEBUG_WX issues I came across >>> aforementioned function and started wondering how pv-ops gets >>> away without the unmapping XenoLinux has always been doing >>> (in free_init_pages()). >> >> Um. I'm not sure why you think something needs to be unmapped. This is >> freeing the pages back to the page allocator -- thus the pages still >> need to be mapped. > > In the 1:1 mapping, yes. But the secondary mapping in the kernel > VA range is not needed anymore, and (unless accounted for) would > get in the way of said operations. The PMDs are shared between the two mappings. See xen_setup_kernel_pagetable(). David