AP_HAL_Linux: make a static-const hal references references to external symbol

libraries/AP_HAL_Linux/AnalogIn_Navio2.cpp

@@ -7,7 +7,7 @@
 
 #include "AnalogIn_Navio2.h"
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 #define ADC_BASE_PATH "/sys/kernel/rcio/adc"
 

libraries/AP_HAL_Linux/GPIO.cpp

@@ -4,7 +4,7 @@
 
 using namespace Linux;
 
-static const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 DigitalSource::DigitalSource(uint8_t v) :
     _v(v)

libraries/AP_HAL_Linux/GPIO_RPI.cpp

@@ -36,7 +36,7 @@
 
 using namespace Linux;
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 GPIO_RPI::GPIO_RPI()
 {

libraries/AP_HAL_Linux/GPIO_Sysfs.cpp

@@ -21,7 +21,7 @@
 
 using namespace Linux;
 
-static const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 #define UINT32_MAX_STR "4294967295"
 

libraries/AP_HAL_Linux/HAL_Linux_Class.cpp

@@ -409,14 +409,14 @@ void HAL_Linux::setup_signal_handlers() const
     sigaction(SIGINT, &sa, NULL);
 }
 
-static HAL_Linux halInstance;
+HAL_Linux hal_linux;
 
 void HAL_Linux::exit_signal_handler(int signum)
 {
-    halInstance._should_exit = true;
+    hal_linux._should_exit = true;
 }
 
 const AP_HAL::HAL &AP_HAL::get_HAL()
 {
-    return halInstance;
+    return hal_linux;
 }

libraries/AP_HAL_Linux/I2CDevice.cpp

@@ -56,9 +56,9 @@
 #define I2C_RDRW_IOCTL_MAX_MSGS 42
 #endif
 
-namespace Linux {
+extern const AP_HAL::HAL& hal;
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+namespace Linux {
 
 /*
  * TODO: move to Util or other upper class to be used by others

libraries/AP_HAL_Linux/Led_Sysfs.cpp

@@ -26,7 +26,7 @@
 
 #include <AP_HAL/AP_HAL.h>
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 namespace Linux {
 

libraries/AP_HAL_Linux/PWM_Sysfs.cpp

@@ -26,7 +26,7 @@
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Math/AP_Math.h>
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 namespace Linux {
 

libraries/AP_HAL_Linux/Perf.cpp

@@ -33,7 +33,7 @@
 
 using namespace Linux;
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 Perf *Perf::_singleton;
 

libraries/AP_HAL_Linux/RCOutput_AeroIO.cpp

@@ -91,7 +91,7 @@ using namespace Linux;
  *     uint16_t duty = 1823;
  */
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 RCOutput_AeroIO::RCOutput_AeroIO()
     : _freq_buffer(new uint16_t[PWM_CHAN_COUNT])

libraries/AP_HAL_Linux/RCOutput_Bebop.cpp

@@ -81,7 +81,7 @@ enum BLDC_STATUS {
 
 using namespace Linux;
 
-static const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 RCOutput_Bebop::RCOutput_Bebop(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev)
     : _dev(std::move(dev))

libraries/AP_HAL_Linux/RCOutput_PCA9685.cpp

@@ -54,7 +54,7 @@ using namespace Linux;
 
 #define PWM_CHAN_COUNT 16
 
-static const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 RCOutput_PCA9685::RCOutput_PCA9685(AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                    bool external_clock,

libraries/AP_HAL_Linux/SPIDevice.cpp

@@ -39,9 +39,9 @@
 
 #define DEBUG 0
 
-namespace Linux {
+extern const AP_HAL::HAL& hal;
 
-static const AP_HAL::HAL &hal = AP_HAL::get_HAL();
+namespace Linux {
 
 #define MHZ (1000U*1000U)
 #define KHZ (1000U)

libraries/AP_Notify/RCOutputRGBLed.cpp

@@ -20,7 +20,7 @@
 #include <AP_Math/AP_Math.h>
 #include <SRV_Channel/SRV_Channel.h>
 
-static const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+extern const AP_HAL::HAL& hal;
 
 #define LED_OFF 0
 #define LED_FULL_BRIGHT 255