spectral/README.md

spectral

A monolithic kernel work wrapper, to make it easy.

Status: the loop closes. Every verb below runs. The chain from a random open bug to a patch that git send-email accepts has been walked end to end, including the v2 re-roll threaded off the original. kernel test builds a tree and boots it under qemu, doctor says what is missing before you start, and init writes the config file. Next in ROADMAP.md has landed; what is left is Later and Far, plus the three gaps named under What is not proven below.

Why

The kernel patch lifecycle is a dozen commands you retype every time. Find something to fix, write it, run checkpatch, run it again after --fix, commit with the right trailer, build, boot it under qemu, diff against master, work out who maintains those files, send. Then a week later do it all again as v2, remembering to thread it off the original.

None of those steps are hard. They are just easy to get subtly wrong, and the ones that get a patch ignored rather than reviewed are the boring details: a missing Signed-off-by, a v2 that does not thread, a maintainer who never got CC'd.

spectral is a thin wrapper over that loop, and the thinness is the point. Every verb shells out to a tool you already have and already trust.

What it wraps

What each verb actually ends up running:

spectral	actually runs
patch check / patch format	scripts/checkpatch.pl from your tree
patch commit	git commit
patch create	git format-patch
patch update	a rename, or git format-patch --reroll-count for a series
patch submit	scripts/get_maintainer.pl from your tree, then git send-email
kernel test	make, then qemu-system-x86_64
kernel quest	the bugzilla.kernel.org REST API
doctor	git, the tree's own scripts, qemu, and the paths

checkpatch.pl and get_maintainer.pl are worth calling out. They come from the tree you are working in, so spectral cannot drift out of date with the kernel's own style rules or maintainer map. Upgrade your tree and the new rules apply.

Because it is thin, you can drop the wrapper at any point. patch submit --dry-run prints the recipients and the exact git send-email command line instead of sending anything. Read it, then either drop --dry-run or run the command yourself.

The loop

What the finished tool feels like. Every line below has been run:

$ spectral kernel quest
12345 usb: xhci: device does not enumerate after resume
component: Drivers/USB
https://bugzilla.kernel.org/show_bug.cgi?id=12345

# ... go and fix it, in the tree ...

$ spectral patch check
$ spectral patch format          # checkpatch --fix, then check again
$ git add -A                     # `patch commit` commits what you staged
$ spectral patch commit "usb: xhci: re-arm the port after resume" --signoff
$ spectral kernel test           # build, then boot it under qemu
$ spectral patch create 000-xhci-port-rearm
~/.spectral/patches/000-xhci-port-rearm.patch

$ spectral patch submit 000-xhci-port-rearm.patch --dry-run
# happy? drop --dry-run and it goes out

# ... wait for review ...

$ spectral patch update 000-xhci-port-rearm.patch -v 2
~/.spectral/patches/v2-000-xhci-port-rearm.patch
$ spectral patch submit v2-000-xhci-port-rearm.patch --in-reply-to '<msg-id-of-v1>'

Staging is yours on purpose. patch commit runs git commit, so what goes in is what you put there; spectral will not sweep a dirty tree into your patch, because a stray file in a kernel patch is a review comment you did not want.

For a set rather than a single patch:

$ spectral patch create xhci-port-rearm --range master..HEAD \
      --cover-letter "Re-arm the port after resume"
~/.spectral/patches/xhci-port-rearm
$ spectral patch submit xhci-port-rearm --dry-run
$ spectral patch update xhci-port-rearm     # -v is inferred; every file moves

The series directory holds the patches plus a series.toml recording the range it was generated for (both ends as hashes), the revision, the file list and the cover letter, which is what lets a re-roll happen without retyping the range. Re-rolling regenerates exactly that range: a commit that landed on the branch since create does not join the set, because a re-roll should not mail commits nobody asked to send. The blurb's first line becomes the cover letter's subject. Leave --cover-letter off and the set is written with git's template subject in it, which git send-email refuses: an unsendable series is better than a cover letter nobody wrote.

One deviation from the obvious design: patch update is a single subcommand taking -v N rather than a generated update-v2 / update-v3. clap subcommands are static, and a flag beats a subcommand you cannot tab-complete. Leave -v off and it infers the next revision from the file's current vN- prefix, or from the sidecar for a series.

Install

Needs a recent stable Rust: edition 2024, so 1.85 or newer. Developed against 1.98.1.

$ git clone https://git.spectoria.dev/huntedbytheirs/spectral.git
$ cd spectral
$ cargo build --release
$ install -Dm755 target/release/spectral ~/.local/bin/spectral

Not on crates.io, so cargo install spectral will get you something else. cargo install --path . from a clone works too.

You also need:

• a kernel tree, for scripts/checkpatch.pl and scripts/get_maintainer.pl. Both ship with the kernel, so spectral does not carry its own.
• git with send-email configured. git send-email has to work from a plain shell first. If it does not, spectral cannot fix it for you and is not meant to try.
• qemu, so that qemu-system-x86_64 is on $PATH, for kernel test.

Configuration

Two paths and a couple of settings, resolved in this order: the environment, then ~/.config/spectral/config.toml, then the built-in default.

what	environment	file key	default
kernel tree	$SPECTRAL_KERNEL	kernel_tree	~/.spectral/linux
patch dir	$SPECTRAL_PATCH_DIR	patch_dir	~/.spectral/patches
always CC		always_cc	none
send-email identity		send_email.from	git's own user.email

$ export SPECTRAL_KERNEL=$HOME/src/linux
$ spectral init --tree $HOME/src/linux      # or --clone <url> [--depth N]
wrote /home/you/.config/spectral/config.toml
tree: /home/you/src/linux

init verifies the tree before it writes anything, and refuses to overwrite a config that points somewhere else unless you pass --force. Run it twice with the same tree and the second run says so and changes nothing.

A tree is accepted only if it has scripts/checkpatch.pl. Otherwise you get not a kernel source tree rather than a confusing failure three steps later. A missing tree reports the path and the variable that would have set it. The tree is not needed for kernel quest, which only wants the network.

A path in the config file has to be absolute, and an unknown key is an error rather than a shrug: a mistyped setting that silently does nothing is worse than one that stops the run and says which line is wrong.

Run spectral doctor to see what got resolved and from where:

$ spectral doctor
ok   kernel tree             /home/you/src/linux (from the config file)
ok   kernel tree shape       scripts/checkpatch.pl is there
ok   checkpatch.pl           scripts/checkpatch.pl (the only thing that decides kernel style)
ok   get_maintainer.pl       scripts/get_maintainer.pl (the only thing that knows who to mail)
ok   MAINTAINERS             the maintainer map the script reads
ok   git                     git version 2.55.0
ok   git send-email          runs
ok   sender identity         [email protected]
warn mail route              no sendemail.* config: --dry-run works, a real send will not
                             -> configure `git send-email` before dropping --dry-run
ok   qemu                    QEMU emulator version 11.1.1
ok   patch directory         /home/you/.spectral/patches (exists, the built-in default)
ok   config file             /home/you/.config/spectral/config.toml
doctor: nothing failed, 1 warned

A warning keeps the exit code at 0; a failed check exits 1 and the summary names the first one, because that is the one to fix first.

Commands

$ spectral --help
A monolithic kernel work wrapper to make it easy.

Usage: spectral <COMMAND>

Commands:
  kernel  Find work, build it, boot it
  patch   Carry a change from working tree to mailing list
  doctor  Check the tree, the scripts, the mail setup and the paths
  init    Point the config at a kernel tree, verifying or cloning one
  help    Print this message or the help of the given subcommand(s)

spectral kernel quest, kernel test

spectral patch check, format, commit, create, submit, update

spectral doctor, init

Every one of them has --help that says more than this README does.

What is not proven

Named rather than papered over, because a thin wrapper is only worth trusting where it says where it stops:

• Real mail is unverified. No patch from this project has been sent to a mailing list by spectral. The acceptance evidence is git send-email --dry-run reaching Dry-OK with the recipients spectral chose.
• A full kernel build is not part of the test suite. kernel test's build step is exercised against a Makefile that writes the image; the boot is exercised against a real qemu with a real bzImage, but nothing here builds a kernel from source, because that is hours of work that proves nothing about this crate.
• patch format's fix round trip is proven against a made-up patch, not against a real kernel posting whose damage checkpatch can repair.

Tests

$ cargo test --locked

No test needs a kernel tree or a network, and none needs git send-email configured. Each one builds a throwaway kernel-shaped git repository in a temp directory, points HOME, SPECTRAL_KERNEL and git's global config at it, and drives the built binary through CARGO_BIN_EXE_spectral. The fixture's PATH and git config are the test's, not the machine's, which is how a missing qemu, a missing sender identity or a missing git send-email is produced deliberately instead of inherited.

One host tool is assumed: git with its send-email support. The doctor tests wrap it so a machine without that support still passes, and the send-email flow tests use the real one, because that is the tool under test.

Three tests do want the host's own tools, and they are ignored unless asked for:

$ SPECTRAL_REAL_CHECKPATCH=1 SPECTRAL_REAL_TREE=/usr/src/linux \
      cargo test --locked -- --ignored real_checkpatch
$ SPECTRAL_REAL_GETMAINTAINER=1 SPECTRAL_REAL_TREE=/usr/src/linux \
      cargo test --locked -- --ignored real_get_maintainer
$ SPECTRAL_LIVE=1 cargo test --locked -- --ignored live_bugzilla

They are where a kernel-version change to checkpatch's summary line, or to get_maintainer's role words, or to bugzilla's REST answer, shows up as a test failure rather than inside someone's patch workflow.

Where to pitch in

The verbs are written and the loop closes. What is left is in ROADMAP.md: Later holds more quest sources, more checks, review tracking and packaging; Far holds the TUI and spectral auto.

Two of those are more useful than they look. kernel/quest.rs is behind the QuestSource trait, so a syzbot source is one impl and no change to the command. patch/series.rs holds the sidecar a series carries, and review tracking is the feature that will want to add to it.

The three gaps at the end of What is not proven are honest small tasks: a real send, a real kernel build under kernel test, and the fix round trip against a real kernel patch.

Development

$ cargo fmt --all
$ cargo clippy --all-targets -- -D warnings
$ cargo test
$ cargo doc --no-deps

All four are clean on main and are the bar for a change.

A few conventions:

• src/cli.rs holds the whole command surface. One file on purpose: the CLI is the specification, and reading it top to bottom should tell you what the tool does.
• Command modules return what they produced and main prints it, so output formatting lives in one place.
• Errors go through the one Error enum and ?. Nothing in the command paths calls unwrap. An external command that fails reports what it said, from stdout as well as stderr, because git puts some refusals on stdout.
• Every module that shells out has a comment saying why that tool and not another API: checkpatch.pl and get_maintainer.pl come from the tree, and git format-patch does the series naming because that is already its job.
• No unsafe and no FFI. std::env::set_var is unsafe under edition 2024, which is why environment-dependent behaviour is tested through the binary rather than in a unit test.
• No todo!() is left in the command path. If you add one, say in the test suite what will prove it gone.

License

MIT. See LICENSE, © 2026 huntedbytheirs.