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SchOS/boot/uefi
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Filename Latest commit message Latest commit date
Nexoniarz 0362427e80 boot/uefi: choose a resolution with R, the same as the BIOS path 
GOP instead of VBE, and the same reasoning. There are no mode numbers
worth hardcoding here: the firmware publishes however many modes the
hardware can do and which index means what varies by machine, so the menu
is built by walking them. Press R within four seconds for a list, then
either a mode number or Enter to type a size. 800x600 stays the floor.

Fixes a header bug this is the first code to notice. The spec's order in
EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE is MaxMode then Mode; efi.h had them
swapped. Info, SizeOfInfo and FrameBufferBase sit at the same offsets
either way because both fields are UINT32, so the framebuffer worked
perfectly and nothing was wrong until something asked how many modes
existed -- and was told the current mode number instead. Zero, on a
machine reporting thirty.

QueryMode and SetMode were void* padding and now have real prototypes;
ConIn likewise, so the loader can read a key. Under OVMF the console
includes the serial line, which is where `make qemu-uefi` puts it and
where the person actually is -- the same mistake the BIOS menu made first
time round.

Verified over serial against OVMF: 30 modes enumerated; picking listed
mode 14 gives 1280x1024; typing 1024x768 gives 1024x768; no key keeps the
firmware's mode and boots. All reach schinit. bootcheck 108 [ok].

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-10 05:30:03 +02:00
..
efi.h boot/uefi: choose a resolution with R, the same as the BIOS path 2026-08-10 05:30:03 +02:00
main.c boot/uefi: choose a resolution with R, the same as the BIOS path 2026-08-10 05:30:03 +02:00
README.md boot: separate BIOS from UEFI 2026-08-09 16:00:03 +02:00
startup.nsh boot/uefi: a working UEFI loader, with one known limitation 2026-08-09 17:13:09 +02:00

README.md

UEFI loader

Not written yet. This directory exists so the BIOS path could be moved into boot/bios/ without pretending the split was hypothetical.

See ../README.md for the hand-off contract a loader has to satisfy. The short version: the kernel wants long mode with paging on, its ELF segments placed, a 24-byte-entry E820-shaped memory map, and framebuffer geometry — and it does not care which firmware produced them.

What this will need, in rough order:

  1. A PE/COFF target. clang can emit one directly (--target=x86_64-unknown-windows -fuse-ld=lld-link), so no new toolchain: the same LLVM install already builds every other target here.
  2. The handful of UEFI structures actually used — the system table, boot services, LOADED_IMAGE, SIMPLE_FILE_SYSTEM, GRAPHICS_OUTPUT. Written from the specification rather than by importing gnu-efi or EDK II, which is both a licence question and a large dependency for something this small.
  3. GetMemoryMap translated into the same 24-byte entries e820.c already parses. Not a second format for the kernel to learn.
  4. ExitBootServices before touching the memory it described.
  5. Graphics Output Protocol for the framebuffer, filling the same VBE_INFO_ADDR structure the BIOS path fills.

The image goes at EFI/BOOT/BOOTX64.EFI on a FAT ESP, which also means the ISO gains an El Torito EFI entry alongside the BIOS one it already has.