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Wed, 18 Mar 2020 02:27:08 -0700 (PDT) MIME-Version: 1.0 References: <1584200119-18594-1-git-send-email-mikelley@microsoft.com> <1584200119-18594-10-git-send-email-mikelley@microsoft.com> In-Reply-To: From: Arnd Bergmann Date: Wed, 18 Mar 2020 10:26:52 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 09/10] arm64: efi: Export screen_info To: Michael Kelley X-Provags-ID: V03:K1:D+PYxEZ8dlW1bGumGz8ORTzFAGiZUTHRZdVxRD0bCXMwaF6WxHe 07LwOxmBo2FYISxuD5h6OJWJGV6cBO+owrJX/wZBwWF3JDICuxF/m9UyLM6EslbZF92FlyO Gu9PlaNPM3YHMcmNUif5EXb07Ba0o0wYE0e+CPpmrpX/7QBjXUvyP5BMa2cPLBgIl+2MUw/ ZRLBuBleICUaqJbs3U+Cg== X-UI-Out-Filterresults: notjunk:1;V03:K0:RWiAdXSV1AQ=:7prXP4ufNXky1fbijTj2Ee rOEqR7DMLju+aJjx7Wd+j+mHiwmDMblj8TnBdP+ovd/M3bUL/VMIrIesx++f66YuzQ3wHYQAH /VP+xo8xlG8oIg0s0YlP/0vc5VoMrVpIed54gq/PnX/Yex8h8Jb2R4GnJnjxP7mUNJ0zOmewI 2nCp+b7dJNkJouT1mkt6urw0P2OAQRi+8c1OuIXr/eiowZXZZu2EgN99sNVJii5jJqCi/tp4Z Az7i38AEbxsSMLMY8Q9cdOyyViElUYiubDO0IYG8tW/fd5QJxu6h+BTtycIzZHcqGWeaOH5PP LWRPQjlR6pWQAqZ1t1vXSIqJpUNlgmooc6QD2qzUjXbSPn3h8f21UbDteAxqGdnApZ8Xyhn3d MP77prti8p3IFh+lVlAniNOt52zvtNRq4saBWjhfNwivT2ln6LuFuZQD+62SAt2PDRdGVt5pK fkUsK9+EZ6UTrSS5HdH/1Zms/gpFX5pZqzXonxSWp0w5EsZpBPf8MOX7RiDLeOK2Qo7xmb4cc q/aKALRlVOJcEtVJdW3YiUwlc7WeV+56v+nvaBGeAp9FdQGwBHUTlryRXfZb9mZ1WWMvC1IQK L+UlR7sZHzJwNa+2wL/C8GcFEVi2rTOmliIdKJ8rOD7aEXuma8YwwGpIDK9DtyNWua622ZCrL waFbGI3heFLNzP0oORfqx+CQ3Wc5mzCqwh9SmdQruca4cT7YAvMAIMPD23U7XCJEQw8tpWo3f WYtX7+WUWPHC3a/yAQwNRUBlWtRZe6GUwer50QEJTIZ4Tcy9ReeK+Z4hOdVkZqTEBDwfx0hdI NutOB3sNbysx7J2/Z+NzhMmw8ZwFY75h+AWW1mD6GCCXZ2w2ac= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200318_022717_660950_8BFF6823 X-CRM114-Status: GOOD ( 15.96 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , linux-arch , "linux-hyperv@vger.kernel.org" , linux-efi , Boqun Feng , gregkh , Catalin Marinas , Jason Wang , Sunil Muthuswamy , "linux-kernel@vger.kernel.org" , "marcelo.cerri@canonical.com" , "olaf@aepfle.de" , Marc Zyngier , Andy Whitcroft , vkuznets , KY Srinivasan , Will Deacon , Ard Biesheuvel , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Mar 18, 2020 at 1:18 AM Michael Kelley wrote: > From: Arnd Bergmann > > On Sat, Mar 14, 2020 at 4:36 PM Michael Kelley wrote: > > > > > > The Hyper-V frame buffer driver may be built as a module, and > > > it needs access to screen_info. So export screen_info. > > > > > > Signed-off-by: Michael Kelley > > > > Is there any chance of using a more modern KMS based driver for the screen > > than the old fbdev subsystem? I had hoped to one day completely remove > > support for the old CONFIG_VIDEO_FBDEV and screen_info from modern > > architectures. > > > > The current hyperv_fb.c driver is all we have today for the synthetic Hyper-V > frame buffer device. That driver builds and runs on both ARM64 and x86. > > I'm not knowledgeable about video/graphics drivers, but when you > say "a more modern KMS based driver", are you meaning one based on > DRM & KMS? Does DRM make sense for a "dumb" frame buffer device? > Are there any drivers that would be a good pattern to look at? It used to be a lot harder to write a DRM driver compared to an fbdev driver, but this has changed to the opposite over the years. A fairly minimal example would be drivers/gpu/drm/pl111/pl111_drv.c or anything in drivers/gpu/drm/tiny/, but you may want to look at the other hypervisor platforms first, i.e drivers/gpu/drm/virtio/virtgpu_drv.c, drivers/gpu/drm/vmwgfx/vmwgfx_drv.c, drivers/gpu/drm/xen/xen_drm_front.c, drivers/gpu/drm/qxl/qxl_drv.c, and drivers/gpu/drm/bochs/bochs_drv.c. Arnd _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel