# GL-AX1800 (Flint1) SDK Research and Cross-Compilation Strategy

**Date:** 2026-01-11  
**Device:** GL-AX1800 (Flint 1)  
**SoC:** Qualcomm IPQ6000 (Quad-core ARM @ 1.2GHz)

## Architecture Confirmation (CORRECTED)

> [!IMPORTANT]
> **Confirmed from actual hardware:**
> - **Flint1 (GL-AX1800)**: ARMv7 rev 4 (v7l) - **32-bit ARM**
> - **Flint2 (GL-MT6000)**: ARMv8 rev 4 (v8l) - **64-bit ARM (aarch64)**
> 
> These are **different architectures** and require **separate binaries**.

### Architecture Details

**GL-AX1800 (Flint1):**
- CPU: ARMv7 Processor rev 4 (v7l)
- Instruction set: 32-bit ARM
- Typical target triplet: `arm-linux-musleabihf` or `armv7l-linux-musleabihf`

**GL-MT6000 (Flint2):**
- CPU: ARMv8 Processor rev 4 (v8l)  
- Instruction set: 64-bit ARM (aarch64)
- Typical target triplet: `aarch64-linux-musl`

---

## SDK Options for GL-AX1800 (ARMv7)

### Option 1: Pre-built musl.cc Toolchain (RECOMMENDED for Quick Start)

**Source:** https://musl.cc/

#### Relevant Toolchains
- `armv7l-linux-musleabihf-cross.tgz` (ARMv7, hard-float)
- `arm-linux-musleabihf-cross.tgz` (Generic ARM, hard-float)

**Download:**
```bash
wget https://musl.cc/armv7l-linux-musleabihf-cross.tgz
tar -xzf armv7l-linux-musleabihf-cross.tgz
export PATH=$PWD/armv7l-linux-musleabihf-cross/bin:$PATH
```

#### Advantages
- Quick setup (download and extract)
- Modern GCC (13.2+) with C++23 support
- Proven for static binary compilation
- Small download (~40-50MB compressed)

#### Disadvantages
- Not optimized for IPQ6000 specifically
- Generic ARMv7 (not Cortex-A7 specific)

---

### Option 2: musl-cross-make (Build Your Own)

**Source:** https://github.com/richfelker/musl-cross-make

#### Configuration for ARMv7
```makefile
TARGET = armv7l-linux-musleabihf
# or: arm-linux-musleabihf
GCC_VER = 14.2.0
MUSL_VER = 1.2.5
LINUX_VER = 6.6.y
GCC_CONFIG += --with-arch=armv7-a --with-fpu=vfpv3-d16 --with-float=hard
```

#### Advantages
- Full control over toolchain versions
- Can build latest GCC 14+ for C++23
- Optimize for Cortex-A7 specifically
- Creates musl-based static-friendly toolchain

#### Disadvantages
- Time-consuming build (30-60 minutes)
- Requires build dependencies
- More complex setup

---

### Option 3: GL.iNet SDK (NOT RECOMMENDED)

**SDK:** `ipq807x-2102`  
**GCC:** 5.5.0 (Too old)  
**Architecture:** arm_cortex-a7 (32-bit)

#### Why Not Use This?
- ❌ GCC 5.5.0 cannot compile C++23 (btop)
- ❌ Outdated toolchain from ~2017
- ❌ Build failures documented in `agent-notes/glax1800-build-results.md`
- ✅ Correct architecture (ARMv7), but toolchain too old

---

## Compilation Requirements

### btop Requirements

**Language:** C++23  
**Minimum GCC:** 11 (experimental), **14+ recommended** (full support)  
**Dependencies:** None (headers only)  
**Build System:** Make or CMake  
**Static Linking:** Fully supported with musl

#### Build Strategy
```bash
# With OpenWrt SDK
make STATIC=true VERBOSE=true CXX=aarch64-openwrt-linux-musl-g++ \
     CXXFLAGS="-static -std=c++23 -O3" LDFLAGS="-static"
```

---

### mosh Requirements

**Language:** C++14  
**Build System:** Autotools (./configure)  
**Dependencies (must be cross-compiled):**
- **protobuf** 3.x (C++ library, requires host protoc)
- **ncurses** 6.x (terminfo)
- **OpenSSL** 1.1.x (or omit with `--without-crypto`)
- **zlib** (compression)

#### Build Strategy (Multi-Stage)

1. **Build host protoc** (x86_64)
   ```bash
   cd protobuf-3.17.3
   ./configure --prefix=/usr/local
   make && sudo make install
   ```

2. **Cross-compile protobuf libraries**
   ```bash
   ./configure --host=aarch64-linux-musl --prefix=$PWD/sysroot \
               --with-protoc=/usr/local/bin/protoc \
               CXXFLAGS="-static" LDFLAGS="-static"
   make && make install
   ```

3. **Cross-compile ncurses**
   ```bash
   ./configure --host=aarch64-linux-musl --prefix=$PWD/sysroot \
               --without-shared --with-normal --without-debug
   make && make install
   ```

4. **Build mosh** (static)
   ```bash
   ./configure --host=aarch64-linux-musl \
               PKG_CONFIG_PATH=$PWD/sysroot/lib/pkgconfig \
               CXXFLAGS="-static" LDFLAGS="-static -pthread" \
               --without-crypto  # Optional: skip OpenSSL
   make
   ```

#### Existing Build Environment
The `src/mosh/` directory already has:
- `env.sh` - Cross-compilation environment
- `sysroot/` - Custom libraries
- `host_protoc/` - Host protobuf compiler
- Built static binaries (for aarch64)

✅ **This can likely be reused or adapted!**

---

## Recommended Approach (CORRECTED)

### Phase 1: Toolchain Setup

**Use musl.cc pre-built ARMv7 toolchain for fastest results:**

```bash
cd /home/user/Public/Projects/OpenWRT/sdk/

# Download ARMv7 hard-float toolchain
wget https://musl.cc/armv7l-linux-musleabihf-cross.tgz
tar -xzf armv7l-linux-musleabihf-cross.tgz

# Add to PATH
export PATH=$PWD/armv7l-linux-musleabihf-cross/bin:$PATH

# Verify
armv7l-linux-musleabihf-gcc --version
```

---

### Phase 2: Build btop for ARMv7

```bash
cd /home/user/Public/Projects/OpenWRT/src/btop

# Clean previous builds
make clean

# Build static for ARMv7
make STATIC=true \
     CXX=armv7l-linux-musleabihf-g++ \
     CXXFLAGS="-static -std=c++23 -O3 -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard" \
     LDFLAGS="-static"

# Verify architecture
file bin/btop
# Should show: ELF 32-bit LSB executable, ARM, EABI5

# Copy to flint1 binaries
cp bin/btop /home/user/Public/Projects/OpenWRT/binaries/flint1/btop/
```

---

### Phase 3: Build mosh for ARMv7

Mosh requires cross-compiling dependencies. Two options:

#### Option A: Adapt Existing Environment

The `src/mosh/` directory has a working setup for aarch64. Update it for ARMv7:

```bash
cd /home/user/Public/Projects/OpenWRT/src/mosh

# Update environment
export PATH=/path/to/armv7l-linux-musleabihf-cross/bin:$PATH
export CC=armv7l-linux-musleabihf-gcc
export CXX=armv7l-linux-musleabihf-g++
export AR=armv7l-linux-musleabihf-ar
export RANLIB=armv7l-linux-musleabihf-ranlib

# Rebuild protobuf for ARMv7
# (Host protoc already built)

# Configure mosh
./configure --host=armv7l-linux-musleabihf \
            CXXFLAGS="-static" \
            LDFLAGS="-static -pthread" \
            --without-crypto

make clean && make
```

#### Option B: Fresh Build

Follow multi-stage process from research document (protobuf → ncurses → mosh).

---

## Next Steps

1. ✅ **Verify architecture** - Confirmed ARMv7 (32-bit ARM) vs ARMv8 (aarch64)
2. ⏭️ **Download ARMv7 toolchain** - Use musl.cc armv7l-linux-musleabihf
3. ⏭️ **Build btop** - Static ARMv7 binary with modern GCC
4. ⏭️ **Build mosh** - Cross-compile dependencies + static linking
5. ⏭️ **Create .ipk packages** - Package for opkg installation
6. ⏭️ **Test on hardware** - Verify on actual GL-AX1800