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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2DF0BC07E9D for ; Tue, 27 Sep 2022 09:38:17 +0000 (UTC) Received: from localhost ([::1]:45418 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1od72e-0007x8-AF for qemu-devel@archiver.kernel.org; Tue, 27 Sep 2022 05:38:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43534) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1od615-0006j3-8v for qemu-devel@nongnu.org; Tue, 27 Sep 2022 04:32:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:50148) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1od611-0002Pv-NA for qemu-devel@nongnu.org; Tue, 27 Sep 2022 04:32:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1664267550; 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=rRnimB01fkjB1gcy7qs2bqVlQaW7rt82H474bXpTsZc=; b=EupxqWTkdAkeg6FWON8ufPDXD8Sruo2LgEqO0vO5FO2BSPt49JVyBseZhK6mH1FRx3hGO0 HABcABiavQAwwZZVhxk1BGHcUXAAYaloR4Fe9XA9FnVhs/uiTYeaA7hZ+aH/MVShYZvyxl UUjEewL5D6KmZmNnE6wZIRvHQUL5+hI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-557-l6i_uI7TM2KhMbxXkVa9Dg-1; Tue, 27 Sep 2022 04:32:27 -0400 X-MC-Unique: l6i_uI7TM2KhMbxXkVa9Dg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B07D7382C96B; Tue, 27 Sep 2022 08:32:26 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.39.192.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7B4E91120AC2; Tue, 27 Sep 2022 08:32:26 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 24CD51800622; Tue, 27 Sep 2022 10:32:25 +0200 (CEST) Date: Tue, 27 Sep 2022 10:32:25 +0200 From: Gerd Hoffmann To: Dmitry Osipenko Cc: Antonio Caggiano , qemu-devel@nongnu.org, gert.wollny@collabora.com, "Michael S. Tsirkin" Subject: Re: [PATCH v2 4/4] virtio-gpu: Don't require udmabuf when blob support is enabled Message-ID: <20220927083225.gdgo6tkv4ssw73yd@sirius.home.kraxel.org> References: <20220913105022.81953-1-antonio.caggiano@collabora.com> <20220913105022.81953-5-antonio.caggiano@collabora.com> <20220923123219.ofn2ygm4knljo6w2@sirius.home.kraxel.org> <6fe0d770-1a95-3d8f-6a75-a596f26aad54@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6fe0d770-1a95-3d8f-6a75-a596f26aad54@collabora.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kraxel@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Sep 26, 2022 at 09:32:40PM +0300, Dmitry Osipenko wrote: > On 9/23/22 15:32, Gerd Hoffmann wrote: > > On Tue, Sep 13, 2022 at 12:50:22PM +0200, Antonio Caggiano wrote: > >> From: Dmitry Osipenko > >> > >> Host blobs don't need udmabuf, it's only needed by guest blobs. The host > >> blobs are utilized by the Mesa virgl driver when persistent memory mapping > >> is needed by a GL buffer, otherwise virgl driver doesn't use blobs. > >> Persistent mapping support bumps GL version from 4.3 to 4.5 in guest. > >> Relax the udmabuf requirement. > > > > What about blob=on,virgl=off? > > > > In that case qemu manages the resources and continued to require > > udmabuf. > > The udmabuf is used only by the blob resource-creation command in Qemu. > I couldn't find when we could hit that udmabuf code path in Qemu because > BLOB_MEM_GUEST resource type is used only by crosvm+Venus when crosvm > uses a dedicated render-server for virglrenderer. Recent enough linux guest driver will use BLOB_MEM_GUEST resources with blob=on + virgl=off > - /dev/udmabuf isn't accessible by normal user > - udmabuf driver isn't shipped by all of the popular Linux distros, > for example Debian doesn't ship it That's why blob resources are off by default. > Because of all of the above, I don't think it makes sense to > hard-require udmabuf at the start of Qemu. It's much better to fail > resource creation dynamically. Disagree. When virgl/venus is enabled, then yes, qemu would let virglrenderer manage resources and I'm ok with whatever requirements virglrenderer has. When qemu manages resources by itself udmabuf is a hard requirement for blob support though. take care, Gerd