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([171.61.161.8]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a8bd74e9bbsm85105ad.95.2026.01.28.09.13.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jan 2026 09:13:07 -0800 (PST) From: Atharva Tiwari To: lukas@wunner.de Cc: airlied@gmail.com, ardb@kernel.org, atharvatiwarilinuxdev@gmail.com, dri-devel@lists.freedesktop.org, francescopompo2@gmail.com, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, jani.nikula@linux.intel.com, javierm@redhat.com, joonas.lahtinen@linux.intel.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, lszubowi@redhat.com, mingo@kernel.org, rodrigo.vivi@intel.com, simona@ffwll.ch, tursulin@ursulin.net, tzimmermann@suse.de Subject: Re: [PATCH v2 0/2] Add support for eGPUs on Apple Products Date: Wed, 28 Jan 2026 17:12:58 +0000 Message-ID: <20260128171258.1081-1-atharvatiwarilinuxdev@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > It's possible that the iMac has a multiplexer built-in which can > switch between the iGPU and dGPU at runtime. Please ensure that > you have set CONFIG_APPLE_GMUX=y in your .config, the gmux driver > should bind to the multiplexer if there is one. > > If there is a multiplexer built-in, then disabling the iGPU is the > wrong approach. I was using apple-gmux even before this patch, and runtime GPU switching does not work on either macOS or Linux. On macOS, the iGPU does not even appear in System Information. However, the iGPU is present in IORegistry, and Apple appears to use it only for acceleration, not for display output. This can be seen from the following IORegistry entry: | | | +-o AppleIntelFramebufferController | | | | | "IOClass" = "AppleIntelFramebufferController" | | | | | "IOPersonalityPublisher" = "com.apple.driver.AppleIntelCFLGraphicsFramebuffer" | | | | | "CFBundleIdentifierKernel" = "com.apple.driver.AppleIntelCFLGraphicsFramebuffer" | | | | | "CFBundleIdentifier" = "com.apple.driver.AppleIntelCFLGraphicsFramebuffer" | | | | | "IOMatchCategory" = "IOFramebuffer" | | | | | "NumFrameBuffer" = <00> NumFrameBuffer=0 says that iGPU isint handling any dispaly atm.