From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753560AbcHXIUg (ORCPT ); Wed, 24 Aug 2016 04:20:36 -0400 Received: from mail-pa0-f51.google.com ([209.85.220.51]:33598 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752865AbcHXIU3 (ORCPT ); Wed, 24 Aug 2016 04:20:29 -0400 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.1 \(1993\)) Subject: Re: [RFC/PATCHSET 0/3] virtio: Implement virtio pstore device (v3) From: Joel In-Reply-To: Date: Wed, 24 Aug 2016 00:10:22 -0700 Cc: "linux-kernel@vger.kernel.org" , qemu-devel , Kees Cook Message-Id: <30A771DF-9BAF-4929-B333-04DF0534D3F6@gmail.com> References: <20160820080744.10344-1-namhyung@kernel.org> <1471947901-3951-1-git-send-email-agnel.joel@gmail.com> To: Namhyung Kim X-Mailer: Apple Mail (2.1993) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id u7O8LuMe028591 Hi Namhyung, > On Aug 23, 2016, at 8:20 AM, Namhyung Kim wrote: > > Hi Joel, > > On Tue, Aug 23, 2016 at 7:25 PM, Joel Fernandes wrote: >> From: Namhyung Kim > >> >> Any thoughts on what you think about it? In your approach though, you >> wouldn't need a backing mem-path file which is the size of the guest >> RAM (which could be as big as the mem-path file). I wonder if the >> mem-path file can be created sparse, and/or Qemu has support to >> configure a certain part of guest RAM as file-backed memory and the >> rest of it from Anonymous memory (not backed by mem-path) so that >> the size of the mem-path file can be kept at a minimum. > > The pstore (ramoops) requires the region of the memory is preserved > across reboot. Is it possible when -mem-path is used? I think it’s I believe the stock qemu won’t persist memory on its own without a reboot. I found atleast one post where someone was trying to make mem-path persist across a reboot and claimed to succeed: https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg03476.html > > Also my approach can handle streams of data bigger than the pstore > buffer size. Although we can extract the contents of mem-path file > periodically, it might be hard for externel process to know the right > time to extract and there's a possibility of information loss IMHO. > I agree, your approach is better for an emulated environment. Thanks, Joel > Thanks, > Namhyung