From patchwork Thu Feb 24 13:24:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12758582 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 244E2C433EF for ; Thu, 24 Feb 2022 13:24:33 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 666F310E155; Thu, 24 Feb 2022 13:24:32 +0000 (UTC) Received: from mail-ej1-x631.google.com (mail-ej1-x631.google.com [IPv6:2a00:1450:4864:20::631]) by gabe.freedesktop.org (Postfix) with ESMTPS id 842A710E155 for ; Thu, 24 Feb 2022 13:24:31 +0000 (UTC) Received: by mail-ej1-x631.google.com with SMTP id vz16so4418988ejb.0 for ; Thu, 24 Feb 2022 05:24:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=alfPJoJ2lpQMy7GyV5GIkRGO5hFrLyMHRmmQh62LRlI=; b=SZX1UsyXsZ55iCmaWj1avilJ5e6FDQaBBtdHRuqKTJBAGrr9NwSmxCumQ7qjuB2zkJ qX28moK16Lwehi9O1RtZmsOSB4YK9pNoHX3kUUNpae7ivjlZqHCLDejHvu/hVihCBb9c xzxTEbJjqSbiNM+OI+DSWDkib3MX5L/zU/tis= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=alfPJoJ2lpQMy7GyV5GIkRGO5hFrLyMHRmmQh62LRlI=; b=JGn5AKJtjvi07mgS+nErh2cCPfJlpttWqfZWzaLuGJn9RwRpUoQC6qVgzL+44lrhi8 rNaYC3lM02wpemnDujrlg6fRz5H2ZkeiGzYhPTnd/K4wzzs0I7XP3Nc50qOfgIHe1RoC YEp4reSHPNryHCOTfNWcZgGguRGd4wQcLfBpTysLMSI1bxSQcLGztTOssoqXMRh2VnoT O8yjR74ohBDV1pNcgezHqkxZZUBcpkUAJlHxlXoDxkwg0WojDCi7zwKB8oTajiJPULzb zqf07MqkNRwYfSUpOI59eyYbhHr9JwUM5Ds0o26FfRgSuTY75BS20yv6hmeQxO6jsBqB Wuew== X-Gm-Message-State: AOAM532kERRlWnlJ4dW22k2umG19//RP9K6Z9jNtqoEq624r7P/HTtTO AzK1A5e0RruN0kAtlA5TzTpJJrrGZqqIIw== X-Google-Smtp-Source: ABdhPJxA83YAFq9B/5sIO9ARYugrmhRjPFdDkvi3VVrEqWFQzrayQltUwoU6KIGGEcqxIWzIC2+bww== X-Received: by 2002:a17:906:7e52:b0:6cf:cf1a:17f with SMTP id z18-20020a1709067e5200b006cfcf1a017fmr2237436ejr.251.1645709070003; Thu, 24 Feb 2022 05:24:30 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id dz8sm1374788edb.96.2022.02.24.05.24.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Feb 2022 05:24:29 -0800 (PST) From: Daniel Vetter To: DRI Development Subject: [PATCH] drm/todo: Update panic handling todo Date: Thu, 24 Feb 2022 14:24:25 +0100 Message-Id: <20220224132425.3463791-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220224125934.3461478-1-daniel.vetter@ffwll.ch> References: <20220224125934.3461478-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 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: Daniel Vetter , Daniel Vetter , Javier Martinez Canillas , gpiccoli@igalia.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Some things changed, and add two useful links. v2: Also include a link to the QR encoding work. Plus review from Javier. Reviewed-by: Javier Martinez Canillas Cc: Javier Martinez Canillas Cc: Pekka Paalanen Cc: gpiccoli@igalia.com Signed-off-by: Daniel Vetter Reviewed-by: Guilherme G. Piccoli Acked-by: Pekka Paalanen --- Documentation/gpu/todo.rst | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 7bf7f2111696..2b1e7fa45603 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -475,8 +475,12 @@ This is a really varied tasks with lots of little bits and pieces: achieved by using an IPI to the local processor. * There's a massive confusion of different panic handlers. DRM fbdev emulation - helpers have one, but on top of that the fbcon code itself also has one. We - need to make sure that they stop fighting over each another. + helpers had their own (long removed), but on top of that the fbcon code itself + also has one. We need to make sure that they stop fighting over each other. + This is worked around by checking ``oops_in_progress`` at various entry points + into the DRM fbdev emulation helpers. A much cleaner approach here would be to + switch fbcon to the `threaded printk support + `_. * ``drm_can_sleep()`` is a mess. It hides real bugs in normal operations and isn't a full solution for panic paths. We need to make sure that it only @@ -488,16 +492,15 @@ This is a really varied tasks with lots of little bits and pieces: even spinlocks (because NMI and hardirq can panic too). We need to either make sure to not call such paths, or trylock everything. Really tricky. -* For the above locking troubles reasons it's pretty much impossible to - attempt a synchronous modeset from panic handlers. The only thing we could - try to achive is an atomic ``set_base`` of the primary plane, and hope that - it shows up. Everything else probably needs to be delayed to some worker or - something else which happens later on. Otherwise it just kills the box - harder, prevent the panic from going out on e.g. netconsole. +* A clean solution would be an entirely separate panic output support in KMS, + bypassing the current fbcon support. See `[PATCH v2 0/3] drm: Add panic handling + `_. -* There's also proposal for a simplied DRM console instead of the full-blown - fbcon and DRM fbdev emulation. Any kind of panic handling tricks should - obviously work for both console, in case we ever get kmslog merged. +* Encoding the actual oops and preceeding dmesg in a QR might help with the + dread "important stuff scrolled away" problem. See `[RFC][PATCH] Oops messages + transfer using QR codes + `_ + for some example code that could be reused. Contact: Daniel Vetter