licence: SchOS is GPL-2.0-or-later, no longer Apache-2.0

Nexoniarz is the sole author and SchOS was never published under
Apache-2.0, so this is a straight relicence. LICENSE is the FSF GPLv2 text,
every first-party SPDX header moves to GPL-2.0-or-later, and NOTICE,
README.md, docs/licensing.md and the site say so. projects/schfs-linux
follows the rest of the tree.

The GPL gives copyleft: a fork has to ship its source. It also lifts the
old "Linux drivers, never" rule, since GPL-2.0-only code combines with
GPL-2.0-or-later. "Or later" leaves room for GPLv3, but one binary still
has to pick one version, so docs/licensing.md now keeps Apache-2.0 and
GPLv3 code out of the kernel to keep Linux code possible there. BSD
4-clause code goes from "avoid" to "no", because the advertising clause
is GPL-incompatible.

LDLS still ships no .ko. That boundary is now project policy rather than
a legal requirement, and ldls.md, devices.md and licensing.md section 6
say so. refmod declares license=GPL, and ldls-check passes (27 checks).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kernel/arch/x86_64/watch.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Hardware watchpoints. docs/architecture/debugging.md milestone D4.
 //

kernel/core/klog.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The kernel log that outlives the kernel. See include/klog.h.
 //

kernel/core/ksym.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Naming an address.
 //

kernel/core/panic.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // PSOGM — the SchOS crash screen.
 //

kernel/core/sbuf.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The bounded string builder. See include/sbuf.h for what it is and why it
 // moved out of kernel/dev/procfs.c.

kernel/dev/dbg.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // /dev/dbg -- asking the kernel a question. See include/dbg.h.
 //

kernel/dev/netuser.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // /dev/netdev -- a network interface whose backend is a process.
 // See include/netuser.h.

kernel/dev/pciuser.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // /dev/pci -- PCI devices, reachable from userspace.
 //

kernel/dev/vt.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Virtual terminals. See include/vt.h for why this exists at all; the short
 // version is that switching needs a backing store, and the console drew

kernel/drivers/bus/xhci/xhci.c

@@ -10,9 +10,9 @@
 // the controller is not complicated; BSD is much more valuable as the
 // reference you check yourself against than as the code you paste.
 //
-// (Licensing points the same way. The BSD stacks are BSD-2/3-clause, which is
-// compatible with Apache-2.0 -- Linux's drivers are GPL-2.0-only, which is
-// not. See docs/guides/adding-a-driver.md.)
+// (Licensing no longer decides it: the BSD stacks are BSD-2/3-clause and
+// Linux's drivers are GPL-2.0-only, and both combine with GPL-2.0-or-later.
+// The argument above is the whole reason. See docs/licensing.md.)
 //
 // Enumeration polls the event ring instead of using interrupts. That is not
 // laziness: pci_bind_all() runs from kmain() with interrupts disabled and no

kernel/fs/devfs.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // devtmpfs: /dev, generated rather than stored.
 //

kernel/fs/schfs/attr.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Attributes, and the index over them.
 //

kernel/fs/schfs/btree.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS copy-on-write B-tree — see btree.h for the contract.
 //

kernel/fs/schfs/kmount.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS in the kernel: block device, mount, and the transaction bracket.
 //

kernel/fs/schfs/obj.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS object layer, read side: inodes, directories and file data.
 //

kernel/fs/schfs/objw.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS object layer, write side: create, link, unlink, rename, write,
 // truncate.

kernel/fs/schfs/schfs_int.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS internals: the volume (uberblock ring, block allocation) and the object
 // layer (inodes, directories, file data) that sit on top of the B-tree.

kernel/fs/schfs/space.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS space manager: which blocks are in use.
 //

kernel/fs/schfs/vfs.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS behind the VFS: the fs_ops table that makes SchFS files reachable
 // through open(2), read(2), write(2) and the rest.

kernel/fs/schfs/vol.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // SchFS volume layer: the uberblock ring.
 //

kernel/net/inet.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // AF_INET sockets, on top of lwIP's raw API.
 //

kernel/net/lwip/arch/cc.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // lwIP's compiler/platform header for SchOS.
 //

kernel/net/lwip/lwipopts.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // lwIP configuration for SchOS.
 //

kernel/net/lwip/netif_eth.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // lwIP network interfaces over the netdev class.
 //

kernel/net/lwip/shim/ctype.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <ctype.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/shim/errno.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <errno.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/shim/inttypes.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <inttypes.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/shim/limits.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <limits.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/shim/stddef.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <stddef.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/shim/stdint.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <stdint.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/shim/stdio.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <stdio.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/shim/stdlib.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // <stdlib.h> for lwIP, shadowing the host's. See shim/string.h for why these
 // files exist at all.

kernel/net/lwip/shim/string.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // <string.h> for lwIP, shadowing the host's.
 //

kernel/net/lwip/shim/unistd.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // <unistd.h> for lwIP, shadowing the host's.
 //
 // Empty on purpose. Everything lwIP would take from this header is supplied by

kernel/net/lwip/sys_arch.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The lwIP port layer: everything lwIP needs from the system it runs on.
 //

kernel/net/net.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The network thread, and the one place the TCP/IP stack is started.
 //

kernel/net/netlink.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // rtnetlink, enough of it that getifaddrs(3) works.
 //

kernel/sys/linux_abi.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 // Linux x86_64 syscall number -> SchOS syscall number translation.
 // Enabled per process by sys_enable_linux_abi (see kernel/sys/sys_compat.c).
 //