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617a4aec0a
A boot printed about thirty lines before reaching a prompt. Every one was
useful once, and printed on every boot for ever they train the person in front
of the machine to stop reading their own console -- which is expensive on the
day one of them changes.
SchOS UEFI loader
Press F8 for boot options... booting
Welcome to SchOS! (F8 at boot for the full log, or dmesg once you are in)
root@schos / »
**Nothing was deleted, it was routed.** consputc() already wrote to the klog
ring before anywhere else, so a line can be kept in full while being held back
from the two places a person looks. kinfo() is cprintf() with that routing, and
`dmesg` still has the whole boot with timestamps afterwards. The rule for which
is which is not how interesting a line is -- everything was interesting to
somebody once -- but whether you would want to see it on a machine that is
*working*. `pci: 7 devices` is yes the first time and no every time after;
`e1000: no DMA memory for the rings` is yes for ever and stays a cprintf.
The verbose boot the F8 menu already offered now means something much bigger,
which is the other half of this: it is the only way to see any of it live.
Userspace follows through /proc/bootmode, one word. schinit, schinitd and vgpud
hold back their progress lines and never their failures -- a supervisor that
goes quiet when a job dies is worse than one that chatters.
Two things found by testing rather than by reading:
- schinit read /proc/bootmode *before* bootstrap() mounted /proc, so it got
"quiet" every time and the verbose boot was quiet in the one process that
runs first. It reads after the mount now.
- resolvconf announced "already exists; -f to replace it" on every boot after
the first, which is a line about having done nothing. It is quiet when the
file already says what it would have written, and speaks only when the two
disagree -- which means the nameserver changed and the machine is using the
old one.
Verified both ways: quiet boot is six lines, a forced-verbose build prints all
thirty plus the `verbose boot:` steps, and /proc/kmsg holds every line in both.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
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| .. | ||
| efi.h | ||
| main.c | ||
| README.md | ||
| startup.nsh | ||
UEFI loader
The loader. This directory once existed only so the BIOS path could be moved
into boot/bios/ without pretending the split was hypothetical; it is now the
only path there is.
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 kernel reads.
The image goes at EFI/BOOT/BOOTX64.EFI on a FAT ESP, which also means the
ISO carries a single El Torito EFI entry.