What should be happening here is that:

  1) The efifb driver initializes, detects a device.
  2) The console driver makes the efifb an active console, and output appears
  3) Later, the astdrmfb initializes, detects a device
  4) The kernel checks for an overlap in the framebuffers used by efifb & 
     to see if they're actually the same physical device.
  5) Overlap is found (they are the same device on ThunderX), so the console 
     actives the preferred astdrmfb driver instead
  6) Console settings are adjusted, output continues

Indeed, this works just like this on a Gigabyte R120 system (same SoC) -
but not on the Cavium CRB. The problem appears to be that UEFI on the
CRB claims the efi framebuffer start address is at 0x10000000 - when it
is really at 0x881010000000 (that's what the Gigabyte system shows). The
kernel assumes this is valid and the efifb driver starts using that
memory and the console driver activates this device... but this isn't
the real location, so nothing appears on VGA. When the astdrm driver
loads, the kernel finds no overlap with the astdrm driver (which is
using the correct window), therefore the console does not attempt to
switch to it, and we continue to not have output.

If I hack the driver to add the 0x8810 prefix, I do begin to see output
at step #2 on the CRB, and the remaining steps work as they should. So,
my assumption is that the framebuffer base is just truncated in

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  Regression: vga term no longer active on Cavium ThunderX

Status in linux package in Ubuntu:
Status in linux source package in Artful:
Status in linux source package in Bionic:

Bug description:
  Cavium ThunderX-based systems, such as the Cavium CRBs and Gigabyte
  implementations, have an ASPEED VGA controller that can be viewed
  remotely using a JAVA application exposed by the BMC. The kernel will
  use serial as the default console on this platform but, with the
  xenial GA (4.4) kernel, boot messages and a login prompt would also
  appear on the VGA display once the DRM stack was initialized during
  boot. You could also override the console default w/ console=tty0 if,
  for example, you wanted to do a d-i install over VGA instead of

  This is no longer the case with later kernels. The significant
  difference is that CONFIG_FB_EFI  is now enabled, starting with this

  commit 44b343e7dd648d738a6b752a81c1ad60c8e0c9b0
  Author: Seth Forshee <seth.fors...@canonical.com>
  Date:   Tue Nov 15 13:45:04 2016 -0600

      UBUNTU: [Config] Enable various drivers for ARM platforms

  This driver detects an EFI framebuffer device, and uses that as the
  default VGA device instead of the ASPEED:

  [    6.426569] efifb: probing for efifb
  [    6.430174] efifb: framebuffer at 0x10000000, using 1200k, total 1200k
  [    6.436703] efifb: mode is 640x480x32, linelength=2560, pages=1
  [    6.442623] efifb: scrolling: redraw
  [    6.446199] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0
  [    6.454324] Console: switching to colour frame buffer device 80x30
  [    6.462878] fb0: EFI VGA frame buffer device
  [    9.320983] ast 0004:21:00.0: enabling device (0002 -> 0003)
  [    9.321192] [drm] Using P2A bridge for configuration
  [    9.321195] [drm] AST 2400 detected
  [    9.321202] [drm] Analog VGA only
  [    9.321213] [drm] dram MCLK=408 Mhz type=6 bus_width=16 size=01000000
  [    9.321351] [TTM] Zone  kernel: Available graphics memory: 65994474 kiB
  [    9.321353] [TTM] Zone   dma32: Available graphics memory: 2097152 kiB
  [    9.321354] [TTM] Initializing pool allocator
  [    9.321386] [TTM] Initializing DMA pool allocator
  [    9.696100] ast 0004:21:00.0: fb1: astdrmfb frame buffer device

  A workaround for this is to disable the efifb device using
  "video=efifb:off". With that in place, I again see output on the
  ASPEED device:

  [    8.799297] ast 0004:21:00.0: enabling device (0002 -> 0003)
  [    8.799449] [drm] Using P2A bridge for configuration
  [    8.799452] [drm] AST 2400 detected
  [    8.799459] [drm] Analog VGA only
  [    8.799470] [drm] dram MCLK=408 Mhz type=6 bus_width=16 size=01000000
  [    8.799602] [TTM] Zone  kernel: Available graphics memory: 65994474 kiB
  [    8.799604] [TTM] Zone   dma32: Available graphics memory: 2097152 kiB
  [    8.799605] [TTM] Initializing pool allocator
  [    8.799614] [TTM] Initializing DMA pool allocator
  [    8.954255] Console: switching to colour frame buffer device 128x48

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