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