allow selection of other OpenCL platform than 0, using --opencl-platform n parameters

eth/main.cpp

@@ -134,6 +134,7 @@ void help()
 		<< "    -f,--force-mining  Mine even when there are no transactions to mine (default: off)" << endl
 		<< "    -C,--cpu  When mining, use the CPU." << endl
 		<< "    -G,--opencl  When mining use the GPU via OpenCL." << endl
+		<< "    --opencl-platform <n>  When mining using -G/--opencl use OpenCL platform n (default: 0)." << endl
 		<< "    --opencl-device <n>  When mining using -G/--opencl use OpenCL device n (default: 0)." << endl
 		<< "Client networking:" << endl
 		<< "    --client-name <name>  Add a name to your client's version string (default: blank)." << endl
@@ -394,6 +395,7 @@ int main(int argc, char** argv)
 
 	/// Mining options
 	MinerType minerType = MinerType::CPU;
+	unsigned openclPlatform = 0;
 	unsigned openclDevice = 0;
 
 	/// File name for import/export.
@@ -511,6 +513,15 @@ int main(int argc, char** argv)
 				cerr << "Bad " << arg << " option: " << argv[i] << endl;
 				return -1;
 			}
+		else if (arg == "--opencl-platform" && i + 1 < argc)
+			try {
+			openclPlatform= stol(argv[++i]);
+		}
+		catch (...)
+		{
+			cerr << "Bad " << arg << " option: " << argv[i] << endl;
+			return -1;
+		}
 		else if (arg == "--opencl-device" && i + 1 < argc)
 			try {
 				openclDevice = stol(argv[++i]);
@@ -809,6 +820,7 @@ int main(int argc, char** argv)
 	if (sessionSecret)
 		sigKey = KeyPair(sessionSecret);
 
+	ProofOfWork::GPUMiner::setDefaultPlatform(openclPlatform);
 	ProofOfWork::GPUMiner::setDefaultDevice(openclDevice);
 
 	// Two codepaths is necessary since named block require database, but numbered

libethash-cl/ethash_cl_miner.cpp

@@ -57,7 +57,7 @@ ethash_cl_miner::ethash_cl_miner()
 {
 }
 
-std::string ethash_cl_miner::platform_info()
+std::string ethash_cl_miner::platform_info(unsigned _platformId, unsigned _deviceId)
 {
 	std::vector<cl::Platform> platforms;
 	cl::Platform::get(&platforms);
@@ -67,21 +67,22 @@ std::string ethash_cl_miner::platform_info()
 		return std::string();
 	}
 
-	// get GPU device of the default platform
+	// get GPU device of the selected platform
 	std::vector<cl::Device> devices;
-	platforms[0].getDevices(CL_DEVICE_TYPE_ALL, &devices);
+	unsigned platform_num = std::min<unsigned>(_platformId, platforms.size() - 1);
+	platforms[platform_num].getDevices(CL_DEVICE_TYPE_ALL, &devices);
 	if (devices.empty())
 	{
 		debugf("No OpenCL devices found.\n");
 		return std::string();
 	}
 
-	// use default device
-	unsigned device_num = 0;
+	// use selected default device
+	unsigned device_num = std::min<unsigned>(_deviceId, devices.size() - 1);
 	cl::Device& device = devices[device_num];
 	std::string device_version = device.getInfo<CL_DEVICE_VERSION>();
 
-	return "{ \"platform\": \"" + platforms[0].getInfo<CL_PLATFORM_NAME>() + "\", \"device\": \"" + device.getInfo<CL_DEVICE_NAME>() + "\", \"version\": \"" + device_version + "\" }";
+	return "{ \"platform\": \"" + platforms[platform_num].getInfo<CL_PLATFORM_NAME>() + "\", \"device\": \"" + device.getInfo<CL_DEVICE_NAME>() + "\", \"version\": \"" + device_version + "\" }";
 }
 
 void ethash_cl_miner::finish()
@@ -92,7 +93,7 @@ void ethash_cl_miner::finish()
 	}
 }
 
-bool ethash_cl_miner::init(ethash_params const& params, std::function<void(void*)> _fillDAG, unsigned workgroup_size, unsigned _deviceId)
+bool ethash_cl_miner::init(ethash_params const& params, std::function<void(void*)> _fillDAG, unsigned workgroup_size, unsigned _platformId, unsigned _deviceId)
 {
 	// store params
 	m_params = params;
@@ -106,12 +107,15 @@ bool ethash_cl_miner::init(ethash_params const& params, std::function<void(void*
 		return false;
 	}
 
-	// use default platform
-	fprintf(stderr, "Using platform: %s\n", platforms[0].getInfo<CL_PLATFORM_NAME>().c_str());
+	// use selected platform
+
+	_platformId = std::min<unsigned>(_platformId, platforms.size() - 1);
+
+	fprintf(stderr, "Using platform: %s\n", platforms[_platformId].getInfo<CL_PLATFORM_NAME>().c_str());
 
     // get GPU device of the default platform
     std::vector<cl::Device> devices;
-    platforms[0].getDevices(CL_DEVICE_TYPE_ALL, &devices);
+	platforms[_platformId].getDevices(CL_DEVICE_TYPE_ALL, &devices);
     if (devices.empty())
 	{
 		debugf("No OpenCL devices found.\n");

libethash-cl/ethash_cl_miner.h

@@ -31,8 +31,8 @@ public:
 public:
 	ethash_cl_miner();
 
-	bool init(ethash_params const& params, std::function<void(void*)> _fillDAG, unsigned workgroup_size = 64, unsigned _deviceId = 0);
-	static std::string platform_info();
+	bool init(ethash_params const& params, std::function<void(void*)> _fillDAG, unsigned workgroup_size = 64, unsigned _platformId = 0, unsigned _deviceId = 0);
+	static std::string platform_info(unsigned _platformId = 0, unsigned _deviceId = 0);
 
 	void finish();
 	void hash(uint8_t* ret, uint8_t const* header, uint64_t nonce, unsigned count);

libethcore/Ethash.cpp

@@ -262,6 +262,7 @@ private:
 	Ethash::GPUMiner* m_owner = nullptr;
 };
 
+unsigned Ethash::GPUMiner::s_platformId = 0;
 unsigned Ethash::GPUMiner::s_deviceId = 0;
 
 Ethash::GPUMiner::GPUMiner(ConstructionInfo const& _ci):
@@ -305,7 +306,7 @@ void Ethash::GPUMiner::workLoop()
 
 		auto p = EthashAux::params(m_minerSeed);
 		auto cb = [&](void* d) { EthashAux::full(m_minerSeed, bytesRef((byte*)d, p.full_size)); };
-		m_miner->init(p, cb, 32, s_deviceId);
+		m_miner->init(p, cb, 32, s_platformId, s_deviceId);
 	}
 
 	uint64_t upper64OfBoundary = (uint64_t)(u64)((u256)w.boundary >> 192);
@@ -320,7 +321,7 @@ void Ethash::GPUMiner::pause()
 
 std::string Ethash::GPUMiner::platformInfo()
 {
-	return ethash_cl_miner::platform_info();
+	return ethash_cl_miner::platform_info(s_platformId, s_deviceId);
 }
 
 #endif

libethcore/Ethash.h

@@ -86,6 +86,7 @@ public:
 
 		static unsigned instances() { return std::thread::hardware_concurrency(); }
 		static std::string platformInfo();
+		static void setDefaultPlatform(unsigned) {}
 		static void setDefaultDevice(unsigned) {}
 
 	protected:
@@ -113,6 +114,7 @@ public:
 
 		static unsigned instances() { return 1; }
 		static std::string platformInfo();
+		static void setDefaultPlatform(unsigned _id) { s_platformId = _id; }
 		static void setDefaultDevice(unsigned _id) { s_deviceId = _id; }
 
 	protected:
@@ -129,6 +131,7 @@ public:
 		ethash_cl_miner* m_miner = nullptr;
 
 		h256 m_minerSeed;		///< Last seed in m_miner
+		static unsigned s_platformId;
 		static unsigned s_deviceId;
 	};
 #else