Hi Thomas, On 11-Oct-25 5:17 PM, Thomas Zimmermann wrote: > Hi Hans > > Am 11.10.25 um 12:02 schrieb Hans de Goede: >> Hi, >> >> A while ago I did a blogpost about not having the native GPU drivers in >> the initrd: https://hansdegoede.dreamwidth.org/28291.html >> >> With the Fedora /boot partition size increase there has been renewed >> interest in this and as a result I got an interesting comment on >> the blog post pointing out that there are EFI protocols to get EDID >> info for the monitor (presumably for the one the GOP has lit up). >> >> It would be useful to see if we can hook this up so that the simpledrm >> device can report the physical dimensions of the screen and the boot >> splash does not need to guess the DPI and thus does not need to guess >> whether to do hiDPI scaling or not. The comment is here: >> >> https://hansdegoede.dreamwidth.org/28291.html?thread=14467#cmt14467 >> >> and it points to: >> >> https://uefi.org/sites/default/files/resources/2_-_AMD_UEFI_Plugfest_EDID_Spring2012.pdf >> https://uefi.org/specs/UEFI/2.9_A/12_Protocols_Console_Support.html >> >> Unfortunately I do not have time to work on this myself, hence this >> email in the hope that someone else can pick this idea up. > > There are now efidrm and vesadrm, which support specifically the features > that we get from the rsp. standards, hardware and bootloader. For VESA and > EFI the EDID can be transferred from grub via bootparams. A patch [1] is on > its way into upstream grub. The Linux kernel stores that data in edid_info, > from where it is picked up by efidrm and vesadrm. If the EFI framebuffer > comes directly from the EFI calls, we need to implement this in the kernel, > but the principle is the same. I also have ideas for making this work on > Coreboot. > > For simpledrm, I'd rather strip if from the ability to use EFI/VESA > framebuffers and focus on simple-framebuffer DT nodes. These sometimes come > with DPI information. Maybe we could extend the DT to support EDID as well. > > [1] https://lists.gnu.org/archive/html/grub-devel/2025-10/msg00043.html > > I have long been working on all this and it is now slowly coming together.
Cool, thank you for working on this! I agree that if we are going to have efidrm and vesadrm that making simpledrm a DT platform thing only makes sense. I do wonder about the choice to primarily make the EDID passing a grub thing though. Some distros are actively trying to move away from grub since grub is quite a complex beast and they are trying to move to something simpler like systemd-boot. As such it would be a good idea IMHO if efidrm could directly get the EDID from EFI itself. Note I'm afraid I don't really have time to work on this myself. Regards, Hans
