On Fri, Dec 10, 2021 at 07:54:34PM -0500, Felix Kuehling wrote:
 

Do you actually need to restore the exact boot-up mode? If you have the same
framebuffer memory layout (width, height, bpp, stride) the precise display
timing doesn't really matter. So we "just" need to switch to a mode that's
compatible with the efifb framebuffer parameters and point the display
engine at the efifb as the scan-out buffer.

That'll probably doable for a normal kexec but in case of a crashdump
kexec I don't think it is a good idea to touch the gpu using the driver
of the kernel which just crashed ...

take care,
  Gerd