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55a585792e
UEFI had no boot menu at all, and asked about resolution in a prompt of
its own before anything else. Two questions at two moments through two
mechanisms is what made the firmwares feel like different programs.
There is one window now: press F8 (or 'o' -- a serial console sends no
scan codes, and that is how this is usually driven) and the same panel
the BIOS loader shows appears, with resolution as a row in it. Selecting
it steps to the next 32bpp mode at or above 800x600 and redraws; the
framebuffer is re-read every pass, because changing mode moves it and
drawing where it used to be is a black screen with no explanation.
Two layout bugs, both visible and both arithmetic:
- TITLE_H was 34 while the heading alone occupies PANEL_PAD + GLYPH_H
= 34, so the rule at TITLE_H - 6 was drawn *through* the lettering
and the first row started on the heading's baseline. TITLE_H is
derived from its parts now and cannot drift from them again.
- the selected row's highlight was offset by a fixed 3px against a
24px row, so it sat on the text rather than around it. It is centred
on the glyph box: (ROW_H - GLYPH_H) / 2 above and below.
Verified from the host: the panel is centred at 640 on a 1280 screen, the
highlight is exactly ROW_H tall and clear of the rule, and Enter boots
through to cpu0. bootcheck 108 [ok], iso builds.
The BIOS resolution chooser is still a separate text prompt, and that is
not an oversight to fix later in the same way. VBE mode setting is an
INT 10h call, so it can only happen in real mode -- before there is any
framebuffer to draw a menu in. Offering it from the graphical menu means
either returning to real mode from long mode, or entering unreal mode to
draw the menu before the switch. Both are real mode-switching work in the
riskiest code in the tree, and neither is a tidy-up.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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| .. | ||
| efi.h | ||
| main.c | ||
| README.md | ||
| startup.nsh | ||
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:
- 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. - 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. GetMemoryMaptranslated into the same 24-byte entriese820.calready parses. Not a second format for the kernel to learn.ExitBootServicesbefore touching the memory it described.- Graphics Output Protocol for the framebuffer, filling the same
VBE_INFO_ADDRstructure 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.