fix crash with monero and strided_index

Strided index 1 is not allowed for cryptonight_v8 and monero.
In the case the dev pool is set to monero and the user tuned there settings for
an other currency the miner will crash if strided index or memChunk is not
fitting the requirement to mine monero.
This PR detects wrong configurations and will set strided index and memChunk to a valid
value but only for cryptonight_v8. The user pool settings will only be changed if monero or
cryptonight_v8 is selected.

xmrstak/backend/amd/amd_gpu/gpu.cpp

@@ -396,12 +396,26 @@ size_t InitOpenCLGpu(cl_context opencl_ctx, GpuContext* ctx, const char* source_
 		int threadMemMask = cn_select_mask(miner_algo[ii]);
 		int hashIterations = cn_select_iter(miner_algo[ii]);
 
+		size_t mem_chunk_exp = 1u << ctx->memChunk;
+		size_t strided_index = ctx->stridedIndex;
+		/* Adjust the config settings to a valid combination
+		 * this is required if the dev pool is mining monero
+		 * but the user tuned there settings for another currency
+		 */
+		if(miner_algo[ii] == cryptonight_monero_v8)
+		{
+			if(ctx->memChunk < 2)
+				mem_chunk_exp = 1u << 2;
+			if(strided_index == 1)
+				strided_index = 0;
+		}
+
 		std::string options;
 		options += " -DITERATIONS=" + std::to_string(hashIterations);
 		options += " -DMASK=" + std::to_string(threadMemMask);
 		options += " -DWORKSIZE=" + std::to_string(ctx->workSize);
-		options += " -DSTRIDED_INDEX=" + std::to_string(ctx->stridedIndex);
-		options += " -DMEM_CHUNK_EXPONENT=" + std::to_string(1u << ctx->memChunk);
+		options += " -DSTRIDED_INDEX=" + std::to_string(strided_index);
+		options += " -DMEM_CHUNK_EXPONENT=" + std::to_string(mem_chunk_exp);
 		options += " -DCOMP_MODE=" + std::to_string(ctx->compMode ? 1u : 0u);
 		options += " -DMEMORY=" + std::to_string(hashMemSize);
 		options += " -DALGO=" + std::to_string(miner_algo[ii]);
@@ -931,20 +945,6 @@ size_t InitOpenCL(GpuContext* ctx, size_t num_gpus, size_t platform_idx)
 			printer::inst()->print_msg(L0, "WARNING %s: gpu %d intensity is not a multiple of 'worksize', auto reduce intensity to %d", backendName.c_str(), ctx[i].deviceIdx, int(reduced_intensity));
 		}
 
-		if(useCryptonight_v8)
-		{
-			if(ctx[i].stridedIndex == 1)
-			{
-				printer::inst()->print_msg(L0, "ERROR %s: gpu %d stridedIndex is not allowed to be `true` or `1` for the selected currency", backendName.c_str(), ctx[i].deviceIdx);
-				return ERR_STUPID_PARAMS;
-			}
-			if(ctx[i].stridedIndex == 2 && ctx[i].memChunk < 2)
-			{
-				printer::inst()->print_msg(L0, "ERROR %s: gpu %d memChunk bust be >= 2 for the selected currency", backendName.c_str(), ctx[i].deviceIdx);
-				return ERR_STUPID_PARAMS;
-			}
-		}
-
 		if((ret = InitOpenCLGpu(opencl_ctx, &ctx[i], source_code.c_str())) != ERR_SUCCESS)
 		{
 			return ret;

xmrstak/backend/amd/config.tpl

@@ -10,7 +10,7 @@ R"===(// generated by XMRSTAK_VERSION
  *                 2 = chunked memory, chunk size is controlled by 'mem_chunk'
  *                     required: intensity must be a multiple of worksize
  *                 1 or true  = use 16byte contiguous memory per thread, the next memory block has offset of intensity blocks
- *                             (not allowed for cryptonight_v8 and monero)
+ *                             (for cryptonight_v8 and monero it is equal to strided_index = 0)
  *                 0 or false = use a contiguous block of memory per thread
  * mem_chunk     - range 0 to 18: set the number of elements (16byte) per chunk
  *                 this value is only used if 'strided_index' == 2