class FieldGateway final {
public:
    int poll();
    int publish(const telemetry_frame& frame);
private:
    linux_serial rs485_;
    mqtt_session mqtt_;
    protocol_decoder decoder_;
};

static int kernel_event_wait(int fd)
{
    struct pollfd pfd { fd, POLLIN, 0 };
    return poll(&pfd, 1, 250);
}

uint16_t holding_registers[128];
modbus_read_registers(ctx, 0x1000, 16, holding_registers);

auto image = buildroot::target("arm-linux-gnueabihf");
auto recipe = yocto::recipe("devsystem-service");

git checkout release/field-2026
git merge feature/diagnostics
git tag -a v2.4.0 -m "field release"

ioctl(fd, DS_IOC_SYNC, &state);
mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
pthread_create(&thread, nullptr, service_loop, &ctx);

struct device_state {
    uint32_t flags;
    uint64_t timestamp;
    double value;
};