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A comment on The Raspberry Beer’o’meter. Parent comment

Re:The Raspberry Beer’o’meter by jchw on Sunday September 15, 2019 @02:31AM (#20975890)
Even if this is true, isn’t that about drivers and not interfaces? Perhaps I am wrong but I was under the impression that the framebuffer userspace device worked on DRM-based drivers still, just it didn’t use fbdev internally.
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Re:The Raspberry Beer’o’meter by dangxiaopin on Sunday September 15, 2019 @02:44AM (#20975918)
I am not 100% sure either, but I think /dev/fbN does not exist without a fb driver. DRM uses /dev/dri/renderNNN
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Re:The Raspberry Beer’o’meter by Const-me on Sunday September 15, 2019 @10:13AM (#20977286)
> DRM uses /dev/dri/renderNNN

It’s /dev/dri/card0 on my device.

DRM has a thing called “dumb framebuffer” which exposes a memory mapped file with the CPU-accessible frame buffer data. See DRM_IOCTL_MODE_CREATE_DUMB and DRM_IOCTL_MODE_MAP_DUMB IOCTLs. The only inconvenience, some boilerplate is required to find the correct GPU connector, and setup a supported video mode.

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