From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43443) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bv5cQ-0004CX-RE for qemu-devel@nongnu.org; Fri, 14 Oct 2016 12:46:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bv5cM-0007gG-KR for qemu-devel@nongnu.org; Fri, 14 Oct 2016 12:46:01 -0400 Received: from mail-wm0-x22b.google.com ([2a00:1450:400c:c09::22b]:35176) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bv5cM-0007g9-Cg for qemu-devel@nongnu.org; Fri, 14 Oct 2016 12:45:58 -0400 Received: by mail-wm0-x22b.google.com with SMTP id c78so8488529wme.0 for ; Fri, 14 Oct 2016 09:45:58 -0700 (PDT) Date: Fri, 14 Oct 2016 17:45:55 +0100 From: Stefan Hajnoczi Message-ID: <20161014164555.GL3482@stefanha-x1.localdomain> References: <20161012140442.GB15590@stefanha-x1.localdomain> <20161013083048.GA2169@work-vm> <20161013142719.GK5613@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="gmhhrsDozM2n+uz5" Content-Disposition: inline In-Reply-To: <20161013142719.GK5613@redhat.com> Subject: Re: [Qemu-devel] Async savevm using userfaultfd(2) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" , qemu-devel , John Snow , "Denis V. Lunev" , Rik van Riel --gmhhrsDozM2n+uz5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Oct 13, 2016 at 04:27:19PM +0200, Andrea Arcangeli wrote: > I would suggest not to implement mprotect+sigsegv because maintaining > both APIs would be messy but mostly because mprotect cannot really > work for all cases and it would risk to fail at any time with > -ENOMEM. postcopy live migration had similar issues and this is why it > wasn't possible to achieve it reliably without userfaultfd. Yes, thanks for explaining the issues. I agree that the mprotect approach isn't worthwhile. We need to use userfaultfd. Stefan --gmhhrsDozM2n+uz5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJYAQvCAAoJEJykq7OBq3PILlcH+wbVIRrxhMsH+Qu+FDJIWRV6 rR69Obm3scKFM+jhGz0tQeD5zR3ITP+Lu7kj/foiHa3d2o5pMzMrW4JeLijb8EmX UZ0IWqlLLgYZnk09OYoxCJzWYNhGSe/qhS6Jpxc3X9Zkv5rfJ8j7Z8r6AFKwLLWv SHg4FIovTCC0/r2CbfcNvAFNchRbcBiAWzHX5Ganlybn/nfdZ4QUInt6MKdmnXzB N51kNvSPcnKtoHT3ocxX3HZnSQ2pvMfNp8J5APYOPoEjKYJMlJinx5FWNlMeJCrM 9K7dVIto0vRmqkk/Hfd//WnpPDMDlDDfN+TGwkDWUU+ZfRXZk1frvlN8fDe9Yos= =XfQt -----END PGP SIGNATURE----- --gmhhrsDozM2n+uz5--