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[92.176.231.205]) by smtp.gmail.com with ESMTPSA id y5-20020a05600c364500b003ee0d191539sm15036395wmq.10.2023.04.04.04.36.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Apr 2023 04:36:43 -0700 (PDT) From: Javier Martinez Canillas To: Samuel =?utf-8?Q?=C4=8Cavoj?= Cc: Thomas Zimmermann , deller@gmx.de, daniel@ffwll.ch, sam@ravnborg.org, maxime@cerno.tech, linux-fbdev@vger.kernel.org, linux-staging@lists.linux.dev, dri-devel@lists.freedesktop.org, Zack Rusin , Daniel Vetter , Alex Deucher , Zhen Lei , Changcheng Deng , Maarten Lankhorst , Maxime Ripard Subject: Re: [PATCH v2 07/11] video/aperture: Disable and unregister sysfb devices via aperture helpers In-Reply-To: References: <20220718072322.8927-1-tzimmermann@suse.de> <20220718072322.8927-8-tzimmermann@suse.de> <9f682c15a5484b4a94f63e20d41f67d0@cavoj.net> <874jqfpw7k.fsf@minerva.mail-host-address-is-not-set> <87706a167c1e490a12371e2edf0f34e3@cavoj.net> <87v8ivoc3r.fsf@minerva.mail-host-address-is-not-set> Date: Tue, 04 Apr 2023 13:36:42 +0200 Message-ID: <87wn2rdgl1.fsf@minerva.mail-host-address-is-not-set> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Samuel =C4=8Cavoj writes: Hello Samuel, > On 2023-03-20 13:12, Javier Martinez Canillas wrote: >> Samuel =C4=8Cavoj writes: >>=20 >> [...] >>=20 >>>>>> This call to sysfb_disable() has been causing trouble with regard=20 >>>>>> to >>>>>> VFIO. VFIO has been calling aperture_remove_conflicting_pci_devices >>>>>> to >>>>>> get rid of any console drivers (d173780620792c) using the device in >>>>>> question, but now even unrelated drivers are getting killed.=20 >>>>>> Example >>>>>> situation: >>>>>=20 >>>>> Which drivers do you use? >>>=20 >>> This happens with either no drivers loaded or the proprietary nvidia >>> driver. Nouveau is fine as it doesn't rely on efifb but brings its=20 >>> own. >>>=20 >>=20 >> Which is what all DRM drivers should do. If they want to make sure that= =20 >> a >> fbdev will be present after the DRM driver probes, then should register= =20 >> an >> emulated fbdev. > > I don't see how this is specific to Nvidia or DRM drivers. > Not specific to Nvidia per se but as mentioned it only affected Nvidia due that driver relying on a different graphics driver to get a VT console. > The efifb is killed if vfio-pci (or another driver which uses the > aperture system to remove conflicting drivers) is bound to ANY pci > device, regardless of whether it's nvidia's fault for not implementing > a framebuffer. Fair enough, I agree that they should, but > I for one expect my efifb to not die at a random time > when a random unrelated driver does a random thing with another > unrelated GPU. > There was a patch series to address that: https://patchwork.kernel.org/project/dri-devel/list/?series=3D711019&archiv= e=3Dboth In particular, this patch: https://patchwork.kernel.org/project/dri-devel/patch/20230111154112.90575-1= 1-daniel.vetter@ffwll.ch/ > Or is the efifb considered a stop-gap solution the only purpose of > which is early boot--before another GPU driver is loaded? > All the firmware-provided graphics drivers are really a best effort IMO, that is something only to be used to get early video output and any in the case of "nomodeset" (i.e: some distros have a "Safe graphics mode" boot entry that prevents DRM drivers to be loaded but used for troubleshooting. But as soon as a real DRM driver is probed (either in the host or a guest when the device is passed-through), I believe that is very likely that it won't work anymore. In other words, is not a robust way to get output and is just a best effort. --=20 Best regards, Javier Martinez Canillas Core Platforms Red Hat