We don't need coreboot to initialize graphics on this boards, this
eliminates some unneeded code and the gnat dependency for them.
Coreboot was using libgfxinit, but it was initializing in text mode.
Heads' kernel will then switch to graphics mode, and we hand that
framebuffer from i915 to the target kernel during kexec.
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
Add CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM and related kernel parameters to
t440p. This board is already on kernel 5.10 and uses i915 graphics.
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
Remove options that haven't deviated from defaults in the Coreboot
Kconfig, despite being saved by `make savedefconfig`. Also, add
`CONFIG_BOARD_LENOVO_THINKPAD_T440P`, which was missing from the `make
savedefconfig` output, causing Heads builds to fail. And finally, bump
`CONFIG_CBFS_SIZE` to `0x800000` (8 MiB to bytes to hexadecimal).
This value for the CBFS size is arbitrary. Originally, I had totaled the
size of all binary blobs, subtracted that from the T440p's ROM size (12
MiB), and used the remaining space as the CBFS size (~11.68 MiB).
However, this caused very long RAM initialization times (courtesy of
`cbmem -t`). And, an anecdote in
https://groups.google.com/a/chromium.org/g/chromium-os-reviews/c/lUqRrGUoEBY/m/ka7L1f2BS8gJ
suggested that this value needs to be a power of 2.
So, I picked a size I expected our Linux payload to fit into that was a
power of 2 that I also expected would leave enough space in the ROM for
the IFD, ME, GbE, and Coreboot.
Now, it takes less than a second for RAM initialization after
flashing/first boot (anecdotally, it seems the MRC needs to be
"trained?").
