include: one folder per subsystem, and includes that name it

Sixty-five headers sat side by side in include/, so `#include "irq.h"`
said nothing about where irq.h was or what it belonged to, and errno.h,
stat.h and fcntl.h at the top shadowed the system's for any host tool
built with -I./include. They are in folders now -- arch/ core/ fs/
dev/ gfx/ net/ uapi/ (and ldls/ for the Linux driver layer) -- and
every include names the folder, as Linux's do: "core/proc.h".

Done mechanically and checked the hard way: the kernel built from this
tree disassembles identically to the one built from the tree before
it. The full image boots, and userland is the same set of programs.
Paths in docs and comments follow; docs/guides/layout.md has a table
of what is where, and tools/fix-includes.py rewrites old-style
includes from the folders in the tree, for code written before this.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

tools/fix-includes.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Rewrite #include "x.h" to the folder x.h lives in under include/.
+#
+# include/ is split by subsystem -- arch/, core/, fs/, dev/, gfx/, net/,
+# uapi/, ldls/ -- and every include names the folder, as Linux's do. Code
+# written before the split, or by habit, says #include "proc.h"; this turns it
+# into #include "core/proc.h". The folder each header is in is read from the
+# tree, so moving a header and running this again is the whole procedure.
+#
+#   python3 tools/fix-includes.py FILE...       rewrite these files
+#   python3 tools/fix-includes.py --modified    every file git says is changed
+#   python3 tools/fix-includes.py --check FILE  print what would change, write
+#                                               nothing; exit 1 if anything would
+#
+# Only quoted includes are touched. <errno.h> in a host tool is the system's
+# errno.h and stays that way, and a file with a same-named header next to it
+# keeps its own.
+
+import os
+import re
+import subprocess
+import sys
+
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+INC = os.path.join(ROOT, "include")
+
+where = {}
+for sub in sorted(os.listdir(INC)):
+    d = os.path.join(INC, sub)
+    if os.path.isdir(d):
+        for h in os.listdir(d):
+            if h.endswith(".h"):
+                where[h] = sub
+
+pat = re.compile(r'(#\s*include\s*")((?:\.\./)*)(include/)?([A-Za-z0-9_]+\.h)"')
+
+
+def fix(path, text):
+    def one(m):
+        pre, dots, incdir, h = m.groups()
+        if h not in where:
+            return m.group(0)
+        if incdir:
+            return '%s%sinclude/%s/%s"' % (pre, dots, where[h], h)
+        if dots or os.path.exists(os.path.join(os.path.dirname(path), h)):
+            return m.group(0)
+        return '%s%s/%s"' % (pre, where[h], h)
+    return pat.sub(one, text)
+
+
+def modified():
+    out = subprocess.run(["git", "-C", ROOT, "status", "--porcelain"],
+                         capture_output=True, text=True, check=True).stdout
+    files = []
+    for line in out.splitlines():
+        p = line[3:].split(" -> ")[-1]
+        if p.endswith((".c", ".h", ".S", ".inc")):
+            files.append(os.path.join(ROOT, p))
+    return files
+
+
+def main(argv):
+    check = "--check" in argv
+    args = [a for a in argv if not a.startswith("--")]
+    files = modified() if "--modified" in argv else args
+    if not files:
+        print(__doc__ or "usage: fix-includes.py [--check] [--modified] FILE...")
+        return 2
+    changed = 0
+    for f in files:
+        if not os.path.isfile(f):
+            continue
+        with open(f, encoding="utf-8", errors="surrogateescape") as fh:
+            old = fh.read()
+        new = fix(f, old)
+        if new == old:
+            continue
+        changed += 1
+        if check:
+            for a, b in zip(old.splitlines(), new.splitlines()):
+                if a != b:
+                    print("%s: %s  ->  %s" % (os.path.relpath(f), a.strip(), b.strip()))
+        else:
+            with open(f, "w", encoding="utf-8", errors="surrogateescape") as fh:
+                fh.write(new)
+            print("fixed", os.path.relpath(f))
+    return 1 if check and changed else 0
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv[1:]))

tools/ksyms.pl

@@ -9,7 +9,7 @@
 #
 # Perl and not Python, deliberately: this runs on every kernel link, so it is
 # on the critical path of a clean build, and tools/vectors.pl already makes
-# perl a requirement there. The Makefile comment above include/logo.h says why
+# perl a requirement there. The Makefile comment above include/gfx/logo.h says why
 # that line is worth holding.
 #
 # Two modes:
@@ -109,7 +109,7 @@ print <<"HDR";
 // places after .text and .rodata so that carrying the table cannot move the
 // addresses recorded in it.
 
-#include "types.h"
+#include "core/types.h"
 
 #define KSYM_SECTION __attribute__((section(".ksym"), used))
 

tools/mkfs.c

@@ -44,10 +44,10 @@
 #define stat     xv6_stat
 #define sigset_t xv6_sigset_t
 #define dirent   schfs_dirent
-#include "../include/types.h"
-#include "../include/param.h"
-#include "../include/fs.h"
-#include "../include/stat.h"
+#include "../include/core/types.h"
+#include "../include/core/param.h"
+#include "../include/fs/fs.h"
+#include "../include/uapi/stat.h"
 #undef dirent
 #undef stat
 #include <dirent.h>
@@ -730,7 +730,7 @@ check_disk_space(void)
             freeblock, fssize, nmeta, nlog, ninodeblocks, nbitmap + nibitmap);
         fprintf(stderr,
             "  Which knob depends on the image:\n"
-            "    the main root image  -> FSSIZE in include/param.h\n"
+            "    the main root image  -> FSSIZE in include/core/param.h\n"
             "    the ramdisk root     -> RAMDISK_BLOCKS in the Makefile\n"
             "  Before growing it, check whether the content belongs here at all:\n"
             "  --exclude <path> drops a subtree, and --ninodes shrinks the\n"

tools/python/mklogo.py

@@ -4,7 +4,7 @@
 Why this exists rather than a PNG decoder in the kernel: the boot logo is one
 fixed image that changes about never, so decoding it at runtime would mean
 carrying an inflate implementation in the kernel forever to answer a question
-that is already known at build time. Precedent is include/font.h, which is the
+that is already known at build time. Precedent is include/gfx/font.h, which is the
 same trade for the same reason.
 
 Output is an 8-bit coverage mask, not colour. The logo is a single-colour
@@ -13,7 +13,7 @@ is ink -- which lets the kernel composite it in whatever the theme's accent
 happens to be, anti-aliased, at one byte per pixel. Storing RGB would be four
 times the size and would hardcode a colour into the kernel image.
 
-    python3 tools/python/mklogo.py docs/branding/shift-mask.png include/logo.h 128
+    python3 tools/python/mklogo.py docs/branding/shift-mask.png include/gfx/logo.h 128
 """
 
 import sys, zlib, struct
@@ -161,7 +161,7 @@ def main():
         f.write('//\n')
         f.write('// An ink-coverage mask, not colour: 0 is background and full scale is\n')
         f.write('// solid logo. Whoever draws it picks the colour, so the palette stays in\n')
-        f.write('// include/theme.h and can change without regenerating anything.\n')
+        f.write('// include/gfx/theme.h and can change without regenerating anything.\n')
         f.write('//\n')
         f.write('// Two pixels per byte, high nibble first. Included by boot/stage2main.c\n')
         f.write('// as well as kernel/dev/vga.c, and stage2 must fit below the 0x10000\n')