Add proprietary libraries policy page. (#25532)

Author: tzarc

docs/_sidebar.json

@@ -21,8 +21,14 @@
             { "text": "Debugging QMK", "link": "/faq_debug" },
             { "text": "Keymap FAQ", "link": "/faq_keymap" },
             { "text": "Squeezing Space from AVR", "link": "/squeezing_avr" },
-            { "text": "Glossary", "link": "/reference_glossary" },
-            { "text": "License Violations", "link": "/license_violations" }
+            { "text": "Glossary", "link": "/reference_glossary" }
+        ]
+    },
+    {
+        "text": "Licensing",
+        "items": [
+            { "text": "License Violations", "link": "/license_violations" },
+            { "text": "Proprietary Libraries", "link": "/proprietary_libs" }
         ]
     },
     {

docs/proprietary_libs.md

@@ -0,0 +1,171 @@
+# Proprietary Vendor Libraries
+
+QMK Firmware cannot include support for any proprietary vendor libraries that impose additional restrictions beyond those in the GPL. This includes binary-only distributions, hardware-locked libraries, and code with redistribution limitations. This document explains why such libraries are incompatible with the GPL-based QMK Firmware and addresses commonly proposed workarounds.
+
+## Architecture Constraints
+
+Firmware presents unique licensing challenges:
+
+- **Monolithic binary**: All code compiles into a single executable image
+- **No OS isolation**: No operating system provides process or memory separation
+- **Shared resources**: All code shares the same memory space, peripherals, and execution context
+- **Static linking**: Everything is statically linked at compile time
+
+This monolithic nature means any proprietary code becomes inseparable from GPL code, creating immediate license violations.
+
+## Common Vendor Library Restrictions
+
+Proprietary vendor libraries typically impose restrictions incompatible with GPL freedoms:
+
+**Hardware Lock-in:**
+- Library only licensed for specific vendor's chips
+- Cannot port firmware to alternative hardware
+- Examples: Nordic's and ST's chip-only clauses in their respective licenses
+
+**No Source Distribution:**
+- Binary-only libraries without corresponding source
+- Precompiled static libraries (.a/.lib files)
+- No ability to modify or fix bugs
+- Examples: WCH CH582 precompiled libraries, Nordic SoftDevice
+
+**Redistribution Limitations:**
+- Restrictions on who can distribute
+- Limitations on commercial use
+- Required permissions or fees
+
+**Additional Legal Terms:**
+- Patent assertions beyond GPL's scope
+- Indemnification requirements
+- Jurisdiction restrictions
+- Explicit anti-GPL clauses
+
+## Bluetooth Stack Licensing Examples
+
+Both Nordic and ST provide Bluetooth stacks under restrictive licenses:
+
+**Nordic SoftDevice (under Nordic 5-clause license):**
+- Binary-only Bluetooth/radio stack
+- License restricts to Nordic hardware
+- No source code available
+- Communicates via SVC interface (still not GPL-compatible)
+
+**ST's Bluetooth Stack (under SLA0044 license):**
+- Explicitly forbids being subject to "Open Source Terms", specifically mentioning incompatibility with the GPL
+- Restricted to ST microcontrollers only
+- Similar functional role to Nordic's SoftDevice
+
+Both represent the same fundamental problem: critical wireless functionality locked behind proprietary licenses.
+
+## Why the System Library Exception Doesn't Apply
+
+The GPL's System Library exception **cannot** rescue proprietary vendor libraries.
+
+### System Library Requirements
+
+The exception only covers libraries that:
+1. Are part of the "normal form of packaging a Major Component"
+2. The Major Component is an OS kernel, compiler, or similar system software
+3. Are not distributed with the application
+4. Are not part of the application itself
+
+### Why Vendor Libraries Fail These Requirements
+
+1. **No operating system**: Bare-metal firmware has no OS to provide system libraries
+2. **Not Major Components**: Hardware drivers and HALs aren't kernels or compilers
+3. **Distributed together**: Vendor code becomes part of the firmware binary
+4. **Application-level code**: Peripheral drivers are application functionality
+
+The exception covers things like Windows system DLLs or Linux glibc, not microcontroller vendor libraries or Bluetooth stacks.
+
+## Attempted Workarounds
+
+### Architectural Separation Attempts
+
+**Supervisor Call (SVC) Interfaces:**
+
+Nordic's SoftDevice uses supervisor call based APIs instead of direct linking:
+- Fixed memory regions for proprietary code
+- Communication through CPU exception mechanisms
+- Claims of "no linking" between components
+
+**Why this fails:** The GPL considers functional integration, not just linking methods. In Bluetooth-capable boards, these would require the proprietary component to function, thus they form a single work regardless of the communication mechanism. This applies equally to Nordic's SoftDevice and any similar architecture ST provides.
+
+**Binary-Only Distributions:**
+
+Multiple vendors provide precompiled libraries:
+- WCH: Precompiled BLE stack
+- Nordic: Binary-only SoftDevice library
+- ST: Same solution as Nordic
+
+**Why this fails:** This is classic static linking of proprietary code into GPL code. The inability to modify these libraries violates GPL's fundamental requirements.
+
+### Loader-Based Separation
+
+- Write a GPL bootloader/loader
+- Load proprietary firmware (such as Nordic/ST Bluetooth) from external storage
+- Claim they're separate works
+
+**Problems:**
+- If designed as a system, courts view as single work
+- Distribution patterns matter (shipped together?)
+- Functional interdependence suggests unity
+- Appears designed to circumvent GPL
+
+## Real-World Examples
+
+### Bluetooth/Wireless Stacks
+- **Nordic SoftDevice**: Binary-only, SVC-interface, hardware-locked
+- **ST Bluetooth**: Binary-only, license explicitly GPL-incompatible
+- **WCH CH582**: Precompiled Bluetooth libraries
+
+### HAL and Driver Libraries
+- **ST HAL/LL drivers**: Source available but SLA0044 restricted
+- **Nordic SDK**: Source visible but 5-Clause restricted
+- **Various vendor HALs**: Platform-locked licenses
+
+### Mixed Proprietary/Open
+- Open peripheral drivers with closed protocol stacks
+- Basic HAL with proprietary performance libraries
+- Partially documented systems requiring binary supplements
+
+## Legal and Practical Consequences
+
+Including any proprietary vendor library means:
+
+1. **License Violation**: Immediate GPL non-compliance
+2. **Distribution Ban**: Users cannot legally share modified firmware
+3. **Commercial Risk**: Products using the firmware face legal liability
+4. **Contributor Tainting**: All GPL contributions become legally problematic
+5. **Update Restrictions**: Cannot fix bugs in proprietary components
+
+## Evaluation Criteria for Libraries
+
+Before including any library, QMK needs to verify:
+- Complete source code available
+- GPL-compatible license (GPL, LGPL, MIT, BSD, Apache)
+- No hardware restrictions
+- No redistribution limitations
+- No additional legal terms
+- No anti-GPL clauses
+
+## Policy Implementation
+
+QMK Firmware maintains a strict policy:
+
+1. **No proprietary libraries**: Regardless of technical workarounds
+2. **No binary blobs**: All code must have source available
+3. **No platform restrictions**: Must allow porting to any hardware
+4. **No additional terms**: Only GPL restrictions permitted
+
+## Summary
+
+There is no legally safe way to include proprietary vendor libraries in GPL firmware. This applies whether they're:
+- Bluetooth stacks (Nordic SoftDevice, ST Bluetooth)
+- Precompiled static libraries
+- Binary blobs with SVC interfaces
+- Source code with restrictive licenses
+- Mixed open/closed systems
+
+**Technical architectures cannot overcome license obligations.**
+
+QMK chooses GPL compliance, ensuring users receive all freedoms the GPL promises.