From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15CBFC433F5 for ; Tue, 5 Oct 2021 07:38:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9FA561507 for ; Tue, 5 Oct 2021 07:38:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232549AbhJEHkP (ORCPT ); Tue, 5 Oct 2021 03:40:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:29506 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230526AbhJEHkO (ORCPT ); Tue, 5 Oct 2021 03:40:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633419504; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=EtTBfJ7umQKOo9c4zQtEMAqccC4CaaUVFj0BPcVpmPk=; b=XiJlvClezweNM6eqgBAgka1GbG0/XUBZCiCbFpQ/qYJ9/NMvGQiXq6uYNtK5WDT7AIglRk MeBdAmWd9pn+yzlyrSydXIsYJV6fpBh3Ly9e9zJsc6/8U5gEM1jWAVrRprzRTwDBxwA1Kq +yoNxUlqZ6s8lgKxrIXFgoTIb5Ue1Ww= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-520-N9l1X2KRMuymU2ciTndIsQ-1; Tue, 05 Oct 2021 03:38:21 -0400 X-MC-Unique: N9l1X2KRMuymU2ciTndIsQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F331DA40C0; Tue, 5 Oct 2021 07:38:19 +0000 (UTC) Received: from localhost (unknown [10.39.192.167]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D750F18A50; Tue, 5 Oct 2021 07:38:07 +0000 (UTC) From: Cornelia Huck To: "Michael S. Tsirkin" Cc: Halil Pasic , Jason Wang , Xie Yongji , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, markver@us.ibm.com, Christian Borntraeger , linux-s390@vger.kernel.org, virtio-dev@lists.oasis-open.org Subject: Re: [virtio-dev] Re: [RFC PATCH 1/1] virtio: write back features before verify In-Reply-To: <20211004160005-mutt-send-email-mst@kernel.org> Organization: Red Hat GmbH References: <87fstm47no.fsf@redhat.com> <20211002141351-mutt-send-email-mst@kernel.org> <20211003070030.658fc94e.pasic@linux.ibm.com> <20211003021027-mutt-send-email-mst@kernel.org> <20211003032253-mutt-send-email-mst@kernel.org> <87ee912e45.fsf@redhat.com> <20211004083455-mutt-send-email-mst@kernel.org> <878rz83lx0.fsf@redhat.com> <20211004110152-mutt-send-email-mst@kernel.org> <87zgro23r1.fsf@redhat.com> <20211004160005-mutt-send-email-mst@kernel.org> User-Agent: Notmuch/0.32.1 (https://notmuchmail.org) Date: Tue, 05 Oct 2021 09:38:05 +0200 Message-ID: <87r1cz2a76.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 04 2021, "Michael S. Tsirkin" wrote: > On Mon, Oct 04, 2021 at 05:45:06PM +0200, Cornelia Huck wrote: >> On Mon, Oct 04 2021, "Michael S. Tsirkin" wrote: >> >> > On Mon, Oct 04, 2021 at 04:27:23PM +0200, Cornelia Huck wrote: >> >> On Mon, Oct 04 2021, "Michael S. Tsirkin" wrote: >> >> >> >> > Do we want to also add explanation that features can be >> >> > changed until FEATURES_OK? >> >> >> >> I always considered that to be implict, as feature negotiation is not >> >> over until we have FEATURES_OK. Not sure whether we need an extra note. >> > >> > Well Halil here says once you set a feature bit you can't clear it. >> > So maybe not ... >> >> Ok, so what about something like >> >> "If FEATURES_OK is not set, the driver MAY change the set of features it >> accepts." >> >> in the device initialization section? > > Maybe "as long as". However Halil implied that some features are not > turned off properly if that happens. Halil could you pls provide > some examples? Yes, "as long as" sounds better.