On Thu, Dec 25, 2025 at 11:10:01PM -0000, Stuart Henderson wrote: > Happens with some machines, we don't know why.
If booting without a monitor connected is working with a regular kernel but failing with the ramdisk kernel, then I'd guess that what is happening is that the system is trying to use the efifb driver to connect to wsdisplay rather than a more specific one which is not included in the ramdisk kernel config, (E.G. inteldrm, radeondrm, or amdgpu). If it's using efifb, no EDID data will be being received as there is no monitor providing it, (a dummy hdmi plug obviously supplies that data, mitigating the problem). That might be confusing the efifb driver, for example if the firmware supplies a value of zero for the x resolution then the driver won't attach. Or maybe the firmware simply doesn't present an efi framebuffer at all if it doesn't see EDID data from a monitor. If it's erroneously using the vga driver on a machine with no physical VGA hardware or firmware emulation of VGA hardware, then it's quite plausible that the machine could crash.
