From nobody Wed Nov 5 15:02:42 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1534939593386859.6514133049578; Wed, 22 Aug 2018 05:06:33 -0700 (PDT) Received: from localhost ([::1]:58666 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fsRu3-00032o-Rq for importer@patchew.org; Wed, 22 Aug 2018 08:06:23 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38851) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fsRp5-0006eA-Ox for qemu-devel@nongnu.org; Wed, 22 Aug 2018 08:01:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fsRp3-0008LD-Bs for qemu-devel@nongnu.org; Wed, 22 Aug 2018 08:01:15 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:46168 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fsRoy-0008EX-CU for qemu-devel@nongnu.org; Wed, 22 Aug 2018 08:01:10 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8BBD77A7EA for ; Wed, 22 Aug 2018 12:01:05 +0000 (UTC) Received: from secure.mitica (ovpn-116-35.ams2.redhat.com [10.36.116.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id D1C4FA9E65; Wed, 22 Aug 2018 12:01:02 +0000 (UTC) From: Juan Quintela To: qemu-devel@nongnu.org Date: Wed, 22 Aug 2018 14:00:33 +0200 Message-Id: <20180822120050.12694-4-quintela@redhat.com> In-Reply-To: <20180822120050.12694-1-quintela@redhat.com> References: <20180822120050.12694-1-quintela@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 22 Aug 2018 12:01:05 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 22 Aug 2018 12:01:05 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'quintela@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 03/20] docs/migration: Clarify pre_load in subsections X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lvivier@redhat.com, dgilbert@redhat.com, peterx@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RDMRC_1 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: "Dr. David Alan Gilbert" Clarify that the pre_load function in a subsection is only called if the subsection is found; to handle a missing subsection you may set values in the pre_load of the parent vmsd. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- docs/devel/migration.rst | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/docs/devel/migration.rst b/docs/devel/migration.rst index 6ed3fce061..687570754d 100644 --- a/docs/devel/migration.rst +++ b/docs/devel/migration.rst @@ -240,10 +240,13 @@ should succeed even with the data missing. To suppor= t this the subsection can be connected to a device property and from there to a versioned machine type. =20 -One important note is that the post_load() function is called "after" -loading all subsections, because a newer subsection could change same -value that it uses. A flag, and the combination of pre_load and post_load -can be used to detect whether a subsection was loaded, and to +The 'pre_load' and 'post_load' functions on subsections are only +called if the subsection is loaded. + +One important note is that the outer post_load() function is called "after" +loading all subsections, because a newer subsection could change the same +value that it uses. A flag, and the combination of outer pre_load and +post_load can be used to detect whether a subsection was loaded, and to fall back on default behaviour when the subsection isn't present. =20 Example: @@ -315,8 +318,8 @@ For example: the property to false. c) Add a static bool support_foo function that tests the property. d) Add a subsection with a .needed set to the support_foo function - e) (potentially) Add a pre_load that sets up a default value for 'foo' - to be used if the subsection isn't loaded. + e) (potentially) Add an outer pre_load that sets up a default value + for 'foo' to be used if the subsection isn't loaded. =20 Now that subsection will not be generated when using an older machine type and the migration stream will be accepted by older --=20 2.17.1