651899220c
1449 lines of boot/bios/, tools/sign.pl and tools/padstage2.pl, plus the build rules, the disk image and the ISO entry that existed to carry them. Everything since roughly 2012 boots UEFI, and CSM -- the firmware-side BIOS emulation that lets a legacy loader run on such a machine at all -- has been going away since Intel dropped support for it in 2020. So this is not a path being retired early; it is one whose remaining hardware is already the exception. The cost was never the code, it was the tax on everything near it. Stage 2 had a 65-sector ceiling it overflowed silently -- 25440 bytes against 24576 -- and because the kernel is written at sector 1 + STAGE2_SECTORS, an overflowing loader was overwritten by the very kernel it was loading. The resolution list could not be shared with UEFI either: VBE mode setting is INT 10h, so matching it needed unreal mode, which is the riskiest code in the tree for a feature that already worked elsewhere. What replaces schos.img is the staged ESP, handed to QEMU as a virtual FAT volume. That is a development arrangement and not an installable disk; a real GPT image with a real FAT partition is the installer's job, and until it exists nothing here writes a disk a machine boots unaided. Secure Boot is untouched too -- the loader is unsigned. The ISO keeps one El Torito entry, the FAT image holding loader and kernel. It never booted from a USB stick via BIOS anyway: the firmware presents the stick as a hard disk while stage2main.c read the kernel back over ATAPI. The 32-bit multiboot entry in entry.S now has no caller and is left in place. Deleting kernel entry code is its own change with its own way of failing silently, and it should not ride along with this one. Ported with it: run.ps1, the six screenshot tools, and schcom_test.sh, each with its own OVMF varstore copy so no run inherits another's UEFI variables. Two things this shook out. OVMF now belongs in `all`: nothing boots without firmware, `make clean` wipes build/ including the copy fetched from the host, and a clean followed by a build left every run script throwing. And it cannot be listed as a prerequisite at the top of the file -- make expands prerequisites when it reads the line, and $(OVMF_CODE) is defined further down, so naming it there appends nothing and says nothing. Verified from a clean tree: 110 [ok] and no failures on the full suite, the ISO boots with no hard disk attached, schfs-check passes, schcom's end-to-end pixel test passes, and fbshot captures a real 1280x800 frame.
131 lines
5.1 KiB
Markdown
131 lines
5.1 KiB
Markdown
<!-- SPDX-License-Identifier: Apache-2.0 -->
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# Moving the project to a Linux machine
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Written for the move to `/home/nexoniarz/Documents/SchOS` on Fedora 44. Nothing
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here is Fedora-specific except the package names.
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## 1. Copy the repo
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Copy the whole directory, `.git` included. Everything that matters is committed
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— 17 commits, no remote — and that includes the project memory, which lives in
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`.claude/memory/` precisely so it survives this.
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```sh
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# whatever transport suits: a USB stick, rsync, scp
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rsync -a /path/to/SchOS/ /home/nexoniarz/Documents/SchOS/
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cd /home/nexoniarz/Documents/SchOS
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git log --oneline | head -3 # should show the same commits
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git status # should be clean
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```
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### What is not in the repo
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`build/`, `sysroot/` and `dist/` are all gitignored, so `rsync -a` of the
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working tree carries them but a `git clone` would not. Two are worth thinking
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about:
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- **`dist/`** holds the upstream tarballs — musl, toybox, mksh, the DOOM WADs,
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`usb.ids`. 61 MB of other people's release artefacts. Copy it to save the
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download, or let the build fetch them again; `make ports` calls `curl` and
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verifies each against a known SHA-256, so a re-download is safe either way.
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Without a network connection, copy it.
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- **`sysroot/`** is assembled by the build, so it does not need copying — and
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on this machine it should not be. Its `bin/` holds musl, toybox and mksh,
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staged once because Windows cannot build them. Linux can, so let `make ports`
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produce them rather than carrying stale binaries across: the staged copies
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predate the rename, and `sysroot/bin/sh` still contains `__schunix_tp`.
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- **`build/`** is pure output. Delete it and forget it.
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## 2. Restore the memory
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Claude Code keeps per-project memory under a key derived from the project's
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absolute path, so it differs per machine:
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|---|---|
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| `D:\DEV\SchOS` | `D--DEV-SchOS` |
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| `/home/nexoniarz/Documents/SchOS` | `-home-nexoniarz-Documents-SchOS` |
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One command puts it where this machine looks:
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```sh
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tools/posix/memory-sync.sh status # shows both sides, changes nothing
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tools/posix/memory-sync.sh import # repo -> ~/.claude/projects/<key>/memory/
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```
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That writes to
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`/home/nexoniarz/.claude/projects/-home-nexoniarz-Documents-SchOS/memory/`.
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After a session that learned something, `export` and commit, so the knowledge
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travels back:
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```sh
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tools/posix/memory-sync.sh export && git add -A && git commit -m "memory: ..."
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```
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## 3. Install the toolchain
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```sh
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tools/posix/setup-fedora.sh --check # report what is missing
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tools/posix/setup-fedora.sh # install it
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```
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That covers clang, lld, llvm, make, gcc, perl, python3, qemu-system-x86,
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edk2-ovmf, xorriso and mtools. See [building.md](building.md) for what each is
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for and for the other supported hosts.
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**PowerShell is the one thing dnf cannot supply.** `tools/windows/bootcheck.ps1`
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is the boot test suite, and `pwsh` runs it on Linux perfectly well — there is
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simply no Fedora package. The script prints the two ways to get it. Nothing
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else needs it: `make`, `make schfs-check` and `make qemu` all work without.
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## 4. Build and check
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```sh
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make # kernel + root filesystem
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make schfs-check # B-tree, object and image suites -- all host-native
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make qemu # boot it
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```
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Two things will behave differently here, both improvements:
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- **`make ports` works.** musl, toybox and mksh build from source. On Windows
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the build skips them and uses whatever is staged.
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- **The SchFS round-trip test runs.** It needs symlinks and hard links, which
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Git Bash cannot create, so on Windows it skips with a message. This is the
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first machine that can actually exercise that path — worth running early,
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since it is the one part of SchFS never yet tested.
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## 5. KVM
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A Ryzen 7000 has SVM, so QEMU can run at native speed instead of emulating:
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```sh
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ls -l /dev/kvm # should exist
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sudo usermod -aG kvm $(id -un) # if it exists but is not readable
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```
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Then add `-enable-kvm` to a QEMU command line. It is deliberately **not** the
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default in the Makefile: the test suite's timings were established under TCG,
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and changing the execution engine underneath them is a variable worth
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introducing on purpose rather than by accident.
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## 6. UEFI
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`make qemu-uefi` boots the UEFI path under OVMF. The Makefile searches the
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usual locations for the firmware and Fedora's `edk2-ovmf`
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(`/usr/share/edk2/ovmf/OVMF_CODE.fd`) is among them.
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Note the open bug before spending time on it: under OVMF the kernel reports
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`e820: only 8 MB usable`, because `e820_init` takes the usable run *containing
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the kernel* and OVMF puts an ACPI NVS region at 0x800000, genuinely fragmenting
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it. The loader's map is correct; the kernel's one-contiguous-run assumption is
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BIOS-shaped. The fix is to free each usable region rather than one range, which
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touches `kalloc`.
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## The hardware, for reference
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Fedora 44, Ryzen 5 7000-series, RTX 4050, 16 GB DDR5. Nothing in the build cares
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about the GPU — QEMU runs headless for tests and uses its own emulated display
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otherwise. The Nvidia driver matters only if you want a QEMU window, and the
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`nouveau`/proprietary choice makes no difference to SchOS either way.
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