2. It doesn't do the right thing for devices that don't
have a display at all...
Thanks for elaborating. Hidden feature that is easy to miss,
indeed. CONFIG_LINEAR_FRAMEBUFFER should be the right thing.
Just one question, is it `VB2_CONTEXT_DISPLAY_INIT` that
is passed on or `VBOOT_WD_FLAG_DISPLAY_INIT`?

VB2_CONTEXT_DISPLAY_INIT is an in+out flag to vb2api_fw_phase1() (the code on the other side is here: https://review.coreboot.org/cgit/vboot.git/tree/firmware/2lib/2api.c#n92). If coreboot already sets it, it will definitely be on. If coreboot doesn't set it, vboot may still independently decide to set it anyway. The final value is then memorized by coreboot as VBOOT_WD_FLAG_DISPLAY_INIT and decides whether to actually initialize the display later in ramstage. (It is also memorized internally in vboot and later used in the payload to tell whether display is available or we need another reboot to turn it on.)

Note that we're planning to get rid of the VBOOT_WD_FLAGs again and instead just persist the vb2_context structure across stages. But that shouldn't make a difference for this. All you need to do is to make sure VB2_CONTEXT_DISPLAY_INIT is set before phase1() on all platforms that either always initialize their display unconditionally, or don't have a display to begin with.

2 comments:

File src/device/Kconfig:
- Patch Set #1, Line 24: config HAVE_VBE_LINEAR_FRAMEBUFFER
  Difference is in Kconfig texts presented to the user in the "Framebuffer […]
  You mean the only difference is whether CONFIG_VBE_LINEAR_FRAMEBUFFER or CONFIG_GENERIC_LINEAR_FRAMEBUFFER is selected down there? But I don't see the difference between those two either. The only place either of them is ever used is in line 441 in this file, where they're ORed together. Why not merge them into one option?
File src/drivers/aspeed/ast2050/Kconfig:
- Patch Set #1, Line 10: select VBOOT_FORCE_DISPLAY_INIT if MAINBOARD_DO_NATIVE_VGA_INIT
  Welcome to the messy PC world :) That a board has this chip, doesn't […]
  Okay, makes sense.

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