6c42ab3b1a
make falls back to the GNU toolchain when clang is absent, and that works for the kernel. It does not work for the UEFI loader: BOOTX64.EFI is PE/COFF and wants clang plus lld-link, so a machine with only gcc gets a kernel that builds and a loader that silently stays whatever it already was. That is not hypothetical -- it is what left a stale boot splash on this tree for half a day. The mask in include/logo.h was the new mark, the kernel drew it, and the loader kept drawing one compiled months earlier because nothing could relink it and nothing said so. shell.nix declares everything docs/guides/building.md lists, and building.md gains a NixOS section saying why using it matters rather than just how. Verified: with clang 21.1.8 and LLD 21.1.8 the loader relinks and the splash draws Shift in metal, screendumped from the framebuffer rather than inferred. Pinned to the host's nixpkgs rather than a flake input, deliberately. This is a convenience for a development machine, not a reproducibility claim; if it ever needs to be the latter it wants a flake and should say so. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
48 lines
1.9 KiB
Nix
48 lines
1.9 KiB
Nix
# A development shell with everything docs/guides/building.md asks for.
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#
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# nix-shell # then: make, make qemu, make iso
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#
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# Why this exists: the UEFI loader is the one part that genuinely cannot be
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# built without clang and lld. `make` falls back to the GNU toolchain for the
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# kernel, so a machine with only gcc gets a kernel that builds and a loader that
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# silently stays whatever it was -- which is exactly the failure that left a
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# stale boot splash on this tree for half a day.
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#
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# Pinned to whatever nixpkgs the host is on rather than to a flake input, on
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# purpose: this is a convenience for one developer's machine, not a
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# reproducibility claim. If it ever needs to be the latter it wants a flake.
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{ pkgs ? import <nixpkgs> { } }:
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pkgs.mkShell {
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name = "schos";
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nativeBuildInputs = with pkgs; [
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# The cross-compiler, and the reason this file exists. clang targets
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# bare-metal ELF, 16-bit code and PE/COFF from one install; lld-link is what
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# produces BOOTX64.EFI.
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clang
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lld
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llvm # llvm-objcopy, llvm-objdump
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# The host compiler, for tools/ -- mkfs, mkschfs, the SchFS suites. Must be
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# a real Unix compiler: those need <unistd.h> and <dirent.h>.
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gcc
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gnumake
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perl # generates the interrupt vector table
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python3 # boot logo, crash-screen QR, mklogo
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qemu # make qemu, and every test harness
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OVMF # firmware for the UEFI path; the Makefile searches for it
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xorriso # make iso
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mtools # ESP staging
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curl gnutar # fetching ports
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];
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shellHook = ''
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echo "schos: clang $(clang --version | head -1 | grep -oE '[0-9]+\.[0-9]+\.[0-9]+')," \
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"$(qemu-system-x86_64 --version | head -1 | grep -oE '[0-9]+\.[0-9]+\.[0-9]+')"
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echo " make | make qemu | make schfs-check | make iso"
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'';
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}
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