Hi Am 23.12.21 um 23:18 schrieb Jan Engelhardt:
On Thursday 2021-12-23 20:17, Frans de Boer wrote:
On 23/12/2021 11:00, Thomas Zimmermann wrote:
tl;dr: Enable DRM for all graphics output and retire fbdev drivers in TW.
I just wonder what this implies for text based output only?
Hm... disabling efifb would mean you get no kernel console on UEFI until e.g. i915 is successfully loaded. Considering that i915 is not part of the initramfs normally and also requires firmware files (which usually are kernel-version specific), something as simple as upgrading the kernel (without kernel-firmware) could potentially produce black screens. That is not a great prospect.
That's exactly what the generic DRM driver is about. [1] It's built into the kenel binary and ready as soon as efifb/vesafb would be. The hardware driver still gets loaded later from the initramfs.
Another consequence is that the kernel footprint will be raised again due to
DirectRendering is practically already present at all times: The moment i915.ko/amdgpu.ko/etc. (or whatever it is you have) loads, and it loads irrespective of whether you use X11 or not, vesafb/efifb gets switched out for inteldrmfb/amdgpudrmfb/etc. (the names were changed in kernel commit 97c9bfe3f6605d41eb8f1206e6e0f62b31ba15d6).
Therefore you lose nothing for which you already paid since practically KMS first became available.
The size of the kernel binary will indeed grow. Some parts of the DRM framework will have to be linked in. We have been working to further modularize DRM to improve the binary size. It only affects the booting, as the DRM modules are already part of the running system today. Best regards Thomas [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/driv... -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev