# Applying the PF-on-Linux patch set / build guide

Both languages: this file is mirrored at `docs/pt-BR/install.md`.

Target: Linux **7.3.4** source tree + out-of-tree modules `pf.ko`
(PF engine, divert(4) family, ifq queues). The port is currently delivered
as a **source tree + zero core patches** (see patches/kernel/README.md):
the module links against symbols the stock 7.3.4 kernel already exports.

## 1. Prerequisites

| Requirement | Why |
|---|---|
| gcc >= 15, GNU make, flex, bison, bc | kernel + pfctl build |
| `glibc-static` (or musl-static) | static pfctl for guest VMs |
| Linux 7.3.4 sources (`/home/lgcosta/lab/linux_kernel/linux-7.3.4`) | build target |
| OpenBSD 8.0 `sys.tar.gz` + `src.tar.gz` | ported sources (fetched + sha256-verified by script; primary mirror openbsd.c3sl.ufpr.br, fallback cdn.openbsd.org) |
| root on the build host | module signing not configured; `insmod` as root |

## 2. Steps

```sh
cd pf_port

# 2.1 fetch + verify OpenBSD 8.0 sources (checksums pinned in VERSIONS)
./scripts/fetch-sources.sh
./scripts/vendorize.sh          # stages _vendor/upstream + IDS.txt

# 2.2 prepare the kernel tree (config + build + external-module prep)
KERNELDIR=/path/to/linux-7.3.4 ./scripts/build-kernel.sh
#   - defconfig + virtio/ext4 built-in (direct kernel boot for the VM lab)
#   - make bzImage modules_prepare
#   - copies vmlinux.symvers -> Module.symvers (needed by M= builds)

# 2.3 apply kernel core patches (currently NONE are required)
./scripts/apply-patches.sh /path/to/linux-7.3.4
#   patches/kernel/series is empty by design; if future milestones need
#   exports, each lands as 000N-*.patch documented in docs/*/patches.md.

# 2.4 build the module and userland
./scripts/build-module.sh        # -> module/pf.ko
make -C tools                    # -> tools/out/pfctl (static)

# 2.5 install on a running 7.3.4 system
sudo insmod module/pf.ko         # creates /dev/pf (0600 root)
sudo cp tools/out/pfctl /usr/local/sbin/
sudo pfctl -e                    # enable
sudo pfctl -f /etc/pf.conf       # real OpenBSD 8.0 syntax
```

## 3. Verify

```sh
pfctl -s info            # "Status: Enabled", live counters
pfctl -nf /etc/pf.conf   # parse-only check
dmesg | grep pfk         # hooks registered (netisr wq data path)
```

VM end-to-end suite (Alpine 3.22 on libvirt): `./scripts/vm-create.sh`,
`./scripts/vm-deploy.sh`, `./scripts/vm-run-tests.sh` — see
`docs/en/vm-lab.md`.

## 4. Uninstall / revert

```sh
sudo pfctl -d; sudo rmmod pf          # flushes rulesets/states
./scripts/unpatch.sh /path/to/linux-7.3.4   # reverse-applies any future patches
```

## 5. What "applied" means here

Because the deliverable is an out-of-tree module, "applying the patch set"
= steps 2.1–2.4; the untouched Linux tree is only *configured and built*
(virtio/EXT4 =y) — no source files are modified unless a future milestone
adds a documented `patches/kernel/000N-*.patch` (all such patches: one
section each in docs/en/patches.md with what/why/impact/revert).