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ACPITOOL v1.1 (Announce)

posted by tkchia Homepage, 03.04.2022, 22:25

Hello Zyzzle,

> Is it possible to create a UEFI BIOS image with a legacy, generic VGA BIOS
> embedded inside? I would think not since that VGA BIOS would rely on DOS
> INT calls and contain legacy 16-bit code which won't run in any UEFI BIOS?
Actually, I would say yes and no. (!)

My extremely experimental biefircate project (https://github.com/tkchia/biefircate) boots up as a UEFI bootloader. However, it tries to find a VGA option ROM among the PC's "Firmware Volumes", and if it does find such an option ROM, it will switch to 16-bit real mode, and run the option ROM to put the display in a VGA-compatible mode. And yes, this works — on some machines, anyway.

But no, a "generic VGA BIOS" will most probably not work. (In particular, I have tried SeaBIOS's VGA BIOS code, and it is simply not enough.) You need an option ROM that knows about the specific kind of display card you are using, so that it can reconfigure the display to a VGA-compatible mode.

Thank you!

---
https://gitlab.com/tkchia · https://codeberg.org/tkchia · 😴 "MOV AX,0D500H+CMOS_REG_D+NMI"

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