On Fri, Dec 26, 2025 at 01:12:18PM +0000, Stuart Henderson wrote: > On 2025/12/26 12:57, Crystal Kolipe wrote: > > 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. > > It needs someone with hardware to investigate really. Comparing GPT > (UEFI, efifb) and MBR (BIOS) installs might give more clues. > I wonder if serial console makes a difference. (If it still reboots > with serial console that gives more debug opportunities).
If nobody with the affected hardware has the resources, (serial console), or knowledge to supply that information then at least it would be useful to have: * a dmesg from a regular booting kernel with monitor attached * a dmesg from a regular booting kernel without monitor attached * a dmesg from the ramdisk kernel with monitor attached Also, what happens when a monitor is plugged in to the crashed system, I.E.: * boot bsd.rd without a monitor connected * wait two or three minutes * connect monitor and observe not only if there is output or not, but whether the monitor even gets sync, (I.E. whether there is any valid signal on the display connector).
