On Sun, 28 Dec 2025 01:23:59 +0100, Crystal Kolipe <[email protected]> wrote: > > Ah, right, I remember casually reading that thread last month :-). > > So resuming: > > The issue has already been identified and it is indeed that no console > attaches for two reasons: > > * RAMDISK doesn't include the same set of drivers that GENERIC does. > > * Efifb which is included sees fb_addr == 0 as set by the firmware, which has > not allocated a framebuffer because there is no EDID data from a monitor. > As a result, efifb doesn't connect. > > Creating a dummy console device, (for example, in the style of Xvfb), is > undesirable because you have to deal with the fact that it can't provide > input, and work around that limitation in a way that doesn't introduce other > issues, although in practice from my work on wscons, I don't see any obvious > reason why it would immediately break due to the lack of input capability. > > In the past this whole situation was uncommon because VGA hardware or > emulation was usually present on most hardware, so failing anything else the > VGA driver was basically always available. > > Thinking further: > > Quite possibly the pre-boot environment on your hardware is using uefi text > mode with a fixed scan rate regardless of what monitor is connected, (or > indeed not connected). > > Unfortunately, whilst uefi text mode is conceptially similar to VGA text mode, > it's a boot service and as such is not usable after calling ExitBootServices() > which would prevent a kernel driver being written to use it. > > However there are other uefi boot services which allow manipulation of the > EDID data, (including presenting completely fake EDID data), and > re-initialising the graphics hardware. Presumably the 'correct' or 'intended' > way to fix this at a firmware level is for the bootloader, (or other UEFI > program), to do this manipulation and allow a framebuffer to be allocated, > then the efifb kernel driver, (and indeed any other OS that subsequently > boots), sees a real framebuffer connected to a virtual monitor. >
The most wired things that it looks that machine is locked somewhere. When I run sysupgrade without serial console hack, it just wait something. As soon as KVM is attached, it continue to boot, make upgrade and everything works fine. And I had asked the technican, he confirmed that he just plug KVM, nothing else. -- wbr, Kirill
