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>

ldls/btf.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Reading BTF. See ldls/btf.h.
 //

ldls/btf.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Reading BTF: struct layouts and function prototypes, from the kernel that
 // the driver was built for.

ldls/host/inspect.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // ldls-inspect -- what is in a relocatable object, and what it wants.
 //

ldls/host/run.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // ldls-run -- load a module and call its init, on the build machine.
 //

ldls/host/types.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // ldls-types -- ask a kernel's BTF where its fields are.
 //

ldls/ko.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Loading a relocatable object. See ldls/ko.h.
 //

ldls/ko.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 #pragma once
 
 // Loading a relocatable object. docs/architecture/ldls.md, "The loader".

ldls/kpi/io.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Register access. See ldls/kpi/kpi.h for the provenance rule.
 //

ldls/kpi/kpi.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The KPI, and the table the loader resolves against. See ldls/kpi/kpi.h.
 //

ldls/kpi/kpi.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The KPI: the Linux symbols a hosted driver actually calls, implemented.
 //

ldls/kpi/net.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The network half of the KPI. See ldls/kpi/kpi.h for the provenance rule.
 //

ldls/kpi/pci.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The PCI half of the KPI. See ldls/kpi/kpi.h for the provenance rule.
 //

ldls/kpi/skb.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Socket buffers. See ldls/kpi/kpi.h for the provenance rule.
 //

ldls/kpi/string.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The string and memory primitives. See ldls/kpi/kpi.h for the provenance rule.
 //

ldls/kpi/thunk.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Retpoline thunks. See ldls/kpi/kpi.h for the provenance rule.
 //

ldls/kpi/work.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // A driver's periodic work. See ldls/kpi/kpi.h for the provenance rule.
 //

ldls/stub.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Stubs. See ldls/stub.h.
 //

ldls/stub.h

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // Stubs: giving every undefined symbol an address that says who it was.
 //

ldls/test/refmod.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
 //
 // The loader's test object. **Ours, on purpose.**
 //
@@ -70,7 +70,7 @@ ldls_test_twice(void)
 // own section. A real one is produced by MODULE_LICENSE() and friends; this is
 // the same bytes by hand, because the macros that emit them are not ours.
 #define MODINFO __attribute__((section(".modinfo"), used, aligned(1)))
-MODINFO static const char mi_license[]     = "license=Apache-2.0";
+MODINFO static const char mi_license[]     = "license=GPL";
 MODINFO static const char mi_description[] = "description=LDLS loader test object";
 MODINFO static const char mi_name[]        = "name=refmod";