[coreboot - Feature #476] Add option to convert coreboot-inited linear frame buffer to efifb directly

[Patrick Rudolph]

Issue #476 has been updated by Patrick Rudolph.

Might be related: https://github.com/torvalds/linux/commit/dff054e691dae

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Feature #476: Add option to convert coreboot-inited linear frame buffer to efifb directly
https://ticket.coreboot.org/issues/476#change-1834

* Author: Bill XIE
* Status: New
* Priority: Normal
* Category: coreboot common code
* Target version: none
* Start date: 2023-03-30
* Related links: https://review.coreboot.org/c/coreboot/+/76428
https://review.coreboot.org/c/coreboot/+/76431
https://review.coreboot.org/c/coreboot/+/76479
* Affected OS: GNU/Linux
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Currently, the linear frame buffer that coreboot initializes should be handled by Linux kernel with dedicated driver "simplefb", but most installer of GNU/Linux distributions only enables "efifb" support, which causes a GNU/Linux installer kexec-ed from a Linux payload running atop simplefb unable to output graphics.

Currently, Grub payload could turn coreboot-initialized simplefb to efifb, which can be easily examined from the dmesg log of GNU/Linux booted from Grub payload running atop coreboot-inited linear frame buffer (simplefb). Chainloading a Linux payload with a minimal Grub payload only containing module "linux" and "cbfs" could make the Linux payload running atop efifb, of which GNU/Linux installers can make use, but the related code could be ported to coreboot to make things easier.