feat: make kernel architecture-agnostic; primitive work on arm port

scripts/check-arch-neutral.sh

@@ -0,0 +1,101 @@
+#!/bin/sh
+# check-arch-neutral.sh - Verify the kernel's architecture boundary.
+#
+# 1. Static rules: outside kernel/src/Arch/, kernel code may not contain
+#    inline assembly, assembly sources, architecture #ifdefs, or includes of
+#    a specific port's headers (it must use the interfaces in Arch/*.hpp).
+# 2. If clang is installed, compile the whole kernel for a second
+#    architecture (default aarch64) and report any symbol the generic code
+#    needs that the port does not define. Links too when ld.lld is found.
+#
+# Usage: ./scripts/check-arch-neutral.sh [arch]
+#
+# Copyright (c) 2026 Daniel Hammer
+
+set -e
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+SRC="$ROOT/kernel/src"
+ARCH="${1:-aarch64}"
+status=0
+
+cd "$SRC"
+
+# Files allowed to name an architecture: the Limine adapter reads the
+# per-architecture MP structures limine.h defines, and Io/IoPort.hpp is an
+# interface header that dispatches to the port like Arch/*.hpp do.
+ALLOW='^(limine\.h|Boot/Protocols/LimineProtocol\.cpp|Io/IoPort\.hpp)$'
+
+generic=$(find . -type f \( -name '*.c' -o -name '*.cpp' -o -name '*.h' -o -name '*.hpp' \) \
+    ! -path './Arch/*' | sed 's|^\./||' | LC_ALL=C sort)
+
+report() {
+    echo "check-arch-neutral: $1" >&2
+    echo "$2" | sed 's/^/    /' >&2
+    status=1
+}
+
+hits=$(grep -nE '(^|[^_[:alnum:]])(asm|__asm__)[[:space:]]*(volatile|\()' $generic || true)
+[ -n "$hits" ] && report "inline assembly outside src/Arch/:" "$hits"
+
+hits=$(find . -type f \( -name '*.asm' -o -name '*.S' -o -name '*.s' \) ! -path './Arch/*')
+[ -n "$hits" ] && report "assembly sources outside src/Arch/:" "$hits"
+
+hits=$(echo "$generic" | grep -vE "$ALLOW" | xargs grep -nE \
+    '__(x86_64|i386|aarch64|arm|riscv|loongarch[0-9]*)__|MONTAUK_ARCH_(X86|AARCH|RISCV|LOONG)[A-Z0-9_]*' || true)
+[ -n "$hits" ] && report "architecture conditionals outside src/Arch/:" "$hits"
+
+hits=$(echo "$generic" | grep -vE "$ALLOW" | xargs grep -nE \
+    '#[[:space:]]*include[[:space:]]*[<"]Arch/[^/>"]+/' || true)
+[ -n "$hits" ] && report "includes of a port's private headers:" "$hits"
+
+if [ $status -eq 0 ]; then
+    echo "check-arch-neutral: static rules OK"
+fi
+
+# ---- Cross-compile check ----
+if ! command -v clang >/dev/null 2>&1; then
+    echo "check-arch-neutral: clang not found, skipping the $ARCH build"
+    exit $status
+fi
+if [ ! -d "Arch/$ARCH" ]; then
+    echo "check-arch-neutral: no src/Arch/$ARCH port" >&2
+    exit 1
+fi
+
+echo "check-arch-neutral: compiling the kernel for $ARCH"
+make -C "$ROOT/kernel" ARCH="$ARCH" objects -j"$(nproc 2>/dev/null || echo 4)" \
+    >/dev/null 2>"$ROOT/kernel/check-arch-$ARCH.log" || {
+    echo "check-arch-neutral: $ARCH compile failed (kernel/check-arch-$ARCH.log):" >&2
+    grep -E 'error' "$ROOT/kernel/check-arch-$ARCH.log" | head -20 >&2
+    exit 1
+}
+rm -f "$ROOT/kernel/check-arch-$ARCH.log"
+
+NM="$(clang -print-prog-name=llvm-nm)"
+command -v "$NM" >/dev/null 2>&1 || NM=nm
+CXXFILT="$(clang -print-prog-name=llvm-cxxfilt)"
+command -v "$CXXFILT" >/dev/null 2>&1 || CXXFILT=cat
+
+cd "$ROOT/kernel"
+objs=$(find "obj-$ARCH" -name '*.o')
+tmp=$(mktemp -d)
+trap 'rm -rf "$tmp"' EXIT
+"$NM" --defined-only -j $objs "cc-runtime-$ARCH/cc-runtime.a" 2>/dev/null | LC_ALL=C sort -u > "$tmp/def"
+"$NM" --undefined-only -j $objs | LC_ALL=C sort -u > "$tmp/undef"
+# Provided by the linker script.
+printf '%s\n' KernelStartSymbol KernelEndSymbol __init_array __init_array_end >> "$tmp/def"
+LC_ALL=C sort -u -o "$tmp/def" "$tmp/def"
+missing=$(LC_ALL=C comm -23 "$tmp/undef" "$tmp/def" | "$CXXFILT")
+if [ -n "$missing" ]; then
+    report "symbols the $ARCH port must still provide:" "$missing"
+    exit 1
+fi
+echo "check-arch-neutral: $ARCH objects compile and every symbol resolves"
+
+if command -v "${KERNEL_LD:-ld.lld}" >/dev/null 2>&1; then
+    make ARCH="$ARCH" >/dev/null
+    echo "check-arch-neutral: linked kernel/bin-$ARCH/kernel"
+fi
+
+exit $status