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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 641A7C3DA7D for ; Thu, 5 Jan 2023 14:16:43 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C049310E10C; Thu, 5 Jan 2023 14:16:42 +0000 (UTC) Received: from mail-wm1-x32a.google.com (mail-wm1-x32a.google.com [IPv6:2a00:1450:4864:20::32a]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3FC0B10E10C for ; Thu, 5 Jan 2023 14:16:41 +0000 (UTC) Received: by mail-wm1-x32a.google.com with SMTP id fm16-20020a05600c0c1000b003d96fb976efso1404685wmb.3 for ; Thu, 05 Jan 2023 06:16:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=8j5hPbefgBGGJHBnsAyQdMEfir+YQPtfFz9+lMOb1kk=; b=MS43t7yLMaxOOYw27ltw2ihRh3bXDSKguTeROQ6X0P6vEVR8/yXWWfWAGKFcjQ9qKQ mXmb4ykZfWTWVe2HFDazsNgLRnlTBYqY9x49K+RanHUSTr76IvYDs4sq8lFetpVYcMuc mqITn65DGKtxcvU5KnrzoxQK5vPzN7hQy6kLk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=8j5hPbefgBGGJHBnsAyQdMEfir+YQPtfFz9+lMOb1kk=; b=ECeh7lFpmgXIKiWPkeUw6+wk2HeZ4+bOlqUy+sCNViSiyYcgqW0WCg4yHciRvn9Iet aph3ntpDxNEl/xW2j/LhTJF+E5v+QhUvy6H0/NhrCzKferj3C5P1ExQHsckloCFTZ5dg iYTPdp9x5AW+g4hG2Bt1d1S4BncrKwx6g7sIAgYtvoHFmxYIzcgLbL0Y0/RSQKwdKrit wLJsjmO0/+C0p4pxbhd03DoyY65eDp+acGMekc90XpL8/g9R5hh+bfnP6vnXhTOI/t0i yi8iQFpIIF0BhL2UaKShIIhLN5AiyXZICkjnS7KpUH6Ek9B8bp0ZHjGgP5BumTcxue77 SScg== X-Gm-Message-State: AFqh2krJpVCCXJKxNOLjEa+cEIKYSVjfTy2hf/wsBYPTBwQaTcI+8LSO SXZPgZJ1S+hMjZR54IAcQNxUyQ== X-Google-Smtp-Source: AMrXdXtZluIu1+RoqDTkX5icw+tri4xuH9ZcJ9XoNEtOvhpmgaaIWHoit8ZaOqAaccmoMv/Zz22XgA== X-Received: by 2002:a05:600c:6016:b0:3d3:3c93:af5e with SMTP id az22-20020a05600c601600b003d33c93af5emr36428987wmb.35.1672928199707; Thu, 05 Jan 2023 06:16:39 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id h8-20020a05600c350800b003d990372dd5sm2825335wmq.20.2023.01.05.06.16.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Jan 2023 06:16:39 -0800 (PST) Date: Thu, 5 Jan 2023 15:16:37 +0100 From: Daniel Vetter To: Yi Xie Subject: Re: [PATCH] drm/vkms: Add a DRM render node to vkms Message-ID: References: <20230105052325.514970-1-yixie@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 5.19.0-2-amd64 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: hamohammed.sa@gmail.com, rodrigosiqueiramelo@gmail.com, dri-devel@lists.freedesktop.org, melissa.srw@gmail.com, lepton@google.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, Jan 05, 2023 at 11:10:23PM +0900, Yi Xie wrote: > On Thu, Jan 5, 2023 at 10:48 PM Daniel Vetter wrote: > > > > On Thu, Jan 05, 2023 at 09:52:26PM +0900, Yi Xie wrote: > > > > This doesn't sound like a good idea to me. Devices without render > > > > capabilities should not fake it. > > > > > > > > User-space (e.g. wlroots) relies on "no render node" to enable > > > > software rendering (Pixman instead of GL). > > > > > > We have virtgpu driver that exports a render node even when virgl is > > > not supported. > > > Mesa has special code path to enable software rendering on it: > > > https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/egl/drivers/dri2/platform_device.c#L296 > > > We can do the same for vkms to force software rendering. > > > > Yeah that is the old kmsro mesa issue, for every combination of kms and > > gem device you need one to make this work. > > > > > On Thu, Jan 5, 2023 at 8:36 PM Daniel Vetter wrote: > > > > > > > > On Thu, Jan 05, 2023 at 02:23:25PM +0900, Yi Xie wrote: > > > > > Some libraries including Mesa and virglrenderer require a render node to > > > > > fully function. By adding a render node to vkms those libraries will > > > > > work properly, supporting use cases like running crosvm with virgl GPU > > > > > support via llvmpipe on a headless virtual machine. > > > > > > > > This is what vgem exists for. More or less at least ... I'm honestly not > > > > really understanding what you're trying to fix here, it sounds a bit like > > > > userspace being stupid. > > > > -Daniel > > > The problem with vgem is that it crashes llvmpipe while working with vkms. > > > Looks like it's due to the same reason as described in this thread in Mesa: > > > https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5830 > > > > I'm not finding any bug description in there and how/why something > > crashes? > > The discussion is in the comment section under the first comment by > Emil Velikov. > It's folded by default (inside "6 replies" at the bottom). > > > > > > Importing buffers allocated by vgem to vkms seems to be unexpected and > > > causes the crash. If we create a render node on vkms then llvmpipe will use > > > vkms to allocate buffers and it no longer crashes. > > > > Uh importing vgem into virtio might not work because those sometimes need > > special buffers iirc. But importing vgem into vkms really should work, > > there's no technical reason it cannot. If it doesn't, then the right fix > > would be to fix that, not paper around it. > > The crash stack trace looks like this: > https://gist.github.com/imxieyi/03053ae79cee2e614850fd41829e1da2 > > Even if we fix the crash issue with vgem, we still need to workaround > quite a few > places that has explicitly blocked vgem. A notable example is virglrenderer: > https://gitlab.freedesktop.org/virgl/virglrenderer/-/blob/master/src/vrend_winsys_gbm.c#L121 > > Actually I have tried to force running virglrenderer on vgem and it > didn't work. I > didn't look into why it wasn't working but I guess that's the reason > for blocking > vgem in the first place. Virglrenderer works well on vkms with render node > enabled though. Ah ok. For next time around, copy a link to the comment you want, e.g. https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5830#note_582477 The 3 dots menu on each comments has an option to copy that link tag. That also highlights the right comment. On this issue, I'm concurring with Emil: "- the import is broken "IMHO that should be fixed, regardless of the rest" The same should be done here. Unless it's a very special device, we should be able to import vgem buffers. -Daniel > > > -Daniel > > > > > > > > > > > > > > > Signed-off-by: Yi Xie > > > > > --- > > > > > drivers/gpu/drm/vkms/vkms_drv.c | 2 +- > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c > > > > > index 293dbca50c31..8eea5d4dece8 100644 > > > > > --- a/drivers/gpu/drm/vkms/vkms_drv.c > > > > > +++ b/drivers/gpu/drm/vkms/vkms_drv.c > > > > > @@ -113,7 +113,7 @@ static void vkms_config_debugfs_init(struct drm_minor *minor) > > > > > } > > > > > > > > > > static const struct drm_driver vkms_driver = { > > > > > - .driver_features = DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM, > > > > > + .driver_features = DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM | DRIVER_RENDER, > > > > > .release = vkms_release, > > > > > .fops = &vkms_driver_fops, > > > > > DRM_GEM_SHMEM_DRIVER_OPS, > > > > > -- > > > > > 2.39.0.314.g84b9a713c41-goog > > > > > > > > > > > > > -- > > > > Daniel Vetter > > > > Software Engineer, Intel Corporation > > > > http://blog.ffwll.ch > > > > -- > > Daniel Vetter > > Software Engineer, Intel Corporation > > http://blog.ffwll.ch -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch